CATHETER INCLUDING ONE OR MORE SENSORS

In one example of the description, a device may have an elongated body defining a lumen. The elongated body may have a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. A first temperature sensor may sense a first temperature of a fluid at a first location in the lumen. A second temperature sensor may sense a second temperature of the fluid at a second location in the lumen. The first location may be proximal to the second location. A heating member may be located proximal to the second temperature sensor. The heating member may heat the fluid within the lumen.

TECHNICAL FIELD

This disclosure relates to medical devices, more particularly, to catheters.

BACKGROUND

Medical devices, such as catheters, may be used to assist a patient in voiding their bladder. In some instances, such catheters may be used during and/or after surgery. In the case of using a catheter to assist a patient in voiding their bladder, a Foley catheter is a type of catheter used for longer time periods than a non-Foley catheter. Some Foley catheters are constructed of silicon rubber and include an anchoring member, which may be an inflatable balloon inflated in a patient's bladder to serve as an anchor, so a proximal end of the catheter does not slip out of the patient's bladder.

SUMMARY

The disclosure describes catheters (e.g., a Foley catheter) and techniques for making and using such catheters. The catheters may include one or more sensor configured to sense one more parameters of fluid within a lumen of the catheter.

In one example, the disclosure relates to a device comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. A first temperature sensor may be configured to sense a first temperature of a fluid at a first location in the lumen. A second temperature sensor may be configured to sense a second temperature of the fluid at a second location in the lumen where the first location is proximal to the second location. A heating member located proximal to the second temperature sensor where the heating member is configured to heat the fluid within the lumen.

In another example, the disclosure relates to a method comprising heating, with a heating member a fluid within a lumen defined by an elongated body comprising a proximal portion and a distal portion. A first temperature sensor may sense a first temperature of a fluid at a first location in the lumen. A second temperature sensor may sense a second temperature of the fluid at a second location in the lumen where the first location is proximal to the second location.

In another example, the disclosure relates to a device comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. A first temperature sensor may be configured to sense a first temperature of a fluid at a first location in the lumen. A second temperature sensor may be configured to sense a second temperature of the fluid at a second location in the lumen, the first location being proximal to the second location. A heating member may be located proximal to the second temperature sensor where the heating member may be configured to heat the fluid within the lumen. Processing circuitry may be configured to determine a flow of the fluid within the lumen based on a difference between the first temperature and the second temperature. An oxygen sensor may be configured to sense oxygen concentration in the fluid within the lumen where the oxygen sensor is configured to be calibrated based on at least one of the first sensed temperature or the second sensed temperature.

In one example, the disclosure relates to a medical device system comprising an elongated body defining a lumen where the elongated body comprising a proximal portion and a distal portion. A sensor coupled to the elongated body where the sensor comprises a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen. The sensor comprising a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen where the second ultrasonic sensor may be positioned on the elongated body proximal to the first ultrasonic sensor. The first ultrasonic sensor is configured to receive the second ultrasonic signal transmitted through the fluid flowing in the lumen. The second ultrasonic sensor is configured to receive the first ultrasonic sound transmitted through the fluid flowing in the lumen.

In another example, the disclosure relates to a method comprising transmitting, with a first ultrasonic sensor, a first ultrasonic signal in a first direction through a fluid flowing distally within a lumen defined by an elongated body comprising a proximal portion and a distal portion. A second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor, transmitting a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen. The first ultrasonic sensor, receiving the second ultrasonic signal transmitted through the fluid flowing in the lumen. The second ultrasonic sensor, receiving the first ultrasonic sound transmitted through the fluid flowing in the lumen.

In another example, the disclosure relates to a medical device system comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. A sensor coupled to the elongated body where the sensor comprises a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen. The sensor comprising a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen where the second ultrasonic sensor may be positioned on the elongated body proximal to the first ultrasonic sensor. Processing circuitry configured to determine a first transit time of the first ultrasonic signal where the first transit time is a time from transmission from the first ultrasonic sensor to reception by the second ultrasonic sensor. The processing circuitry configured to determine a second transit time of the second ultrasonic signal where the second transit time is a time from transmission from the second ultrasonic sensor to reception by the first ultrasonic sensor. The processing circuitry configured to determine a flow velocity of the fluid through the lumen based on the determined first and second transit times of the first and the second ultrasonic signals. The first ultrasonic sensor is configured to receive the second ultrasonic signal transmitted through the fluid flowing in the lumen. The second ultrasonic sensor is configured to receive the first ultrasonic sound transmitted through the fluid flowing in the lumen.

In one example, the disclosure relates to a system comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. An anchoring member positioned on the proximal portion of the elongated body. The system further comprising a fluorescence material configured to be located within the lumen with a fluid in the lumen. A light source configured to emit light to expose the fluorescence material to the emitted light where the fluorescence material within the fluid is configured to fluoresce when exposed to the light in the lumen. The system further comprising a light detector configured to detect the fluorescence of the fluorescence material. The system configured to detect oxygen in the fluid within the lumen based on the detected fluorescence

In another example, the disclosure relates to a method comprising controlling a light source to emit light to expose a fluorescence material to the emitted light where the fluorescence material within a fluid is configured to fluoresce when exposed to the light in the lumen defined by an elongated body comprising a proximal portion and a distal portion. Detecting, with a light detector, the fluorescence of the fluorescence material. Determining, based on the detected fluorescence, oxygen in the fluid within the lumen.

In another example, the disclosure relates to a system comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. The system further comprising an anchoring member positioned on the proximal portion of the elongated body. The system comprising a fluorescence material configured to be located within the lumen with a fluid in the lumen. A light source configured to emit light to expose the fluorescence material to the emitted light where the fluorescence material within the fluid is configured to fluoresce when exposed to the light in the lumen. A light detector configured to detect the fluorescence of the fluorescence material. A sensor body configured to be releasably coupled to the elongated body, the sensor body supporting the light source and the light detector. A lens configured to be placed on the elongated body in between the fluorescence material and light source. A first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen. A second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen where the second ultrasonic sensor may be positioned on the elongated body proximal to the first ultrasonic sensor. The system is configured to detect oxygen in the fluid within the lumen based on the detected fluorescence.

In one example, the disclosure relates to a system comprising an elongated body defining a lumen where the elongated body comprising a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. The system further comprising a sensor located on the elongated body where the sensor may be configured to sense at least one flow parameter of a fluid within the lumen. Processing circuitry configured to determine at least one of a density parameter or a temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid.

In another example, the disclosure relates to a method comprising sensing, with a sensor located on an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion, at least one flow parameter of a fluid within the lumen. The method further comprising, determining, with processing circuitry, at least one of a density parameter or a temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid.

In another example, the disclosure relates to a system comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. The system further comprising a sensor located on the elongated body where the sensor may be configured to sense at least one flow parameter of a fluid within the lumen. Processing circuitry may be configured to determine at least one of a density parameter or a temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid. The system further comprising a temperature sensor configured to determine a temperature of the fluid within the lumen where the processing circuitry is configured to determine the density parameter of the fluid based on the at least one flow parameter and the determined temperature of the fluid.

In one example, the disclosure relates to a catheter system comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. The system further comprising at least one sensor configured to be coupled to the elongated body where the at least one sensor may be configured to sense one or more parameters of a fluid within the lumen of the elongate body. Memory configured to be coupled to the elongated body where the memory may be configured to store sensor calibration information. The system configured to calibrate the at least one sensor based on the sensor calibration information stored by the memory.

In another example, the disclosure relates to a method comprising sensing, with at least one sensor configured to be coupled to an elongated body defining a lumen and the elongated body comprising a proximal portion and a distal portion, one or more parameters of a fluid within the lumen of the elongate body. Storing, with a memory configured to be coupled to the elongated body, sensor calibration information. The method further comprising calibrating the at least one sensor based on sensor calibration information stored by the memory.

In another example, the disclosure relates to a catheter system comprising an elongated body defining a lumen where the elongated body comprises a proximal portion and a distal portion. An anchoring member may be positioned on the proximal portion of the elongated body. The system further comprising a flow sensor configured to sense a flow rate of the fluid in the lumen. An oxygen sensor configured to sense the amount of oxygen within the fluid in the lumen. The system further comprising memory configured to be coupled to the elongated body where the memory may be configured to store sensor calibration information. The system is configured to calibrate the flow sensor and/or the oxygen sensor based on the sensor calibration information stored by the memory.

DETAILED DESCRIPTION

In general, the disclosure describes a medical device and systems including a catheter, such as a Foley catheter or other urinary or non-urinary catheter, and methods of making and using the same. As will be described below, examples of the disclosure may include catheters having one or more sensors configured to sense one or more parameters of a fluid such as urine within a lumen of the catheter body (e.g., the drainage lumen). Example sensed parameters may include flow rate of the fluid, temperature of the fluid, density of the fluid, and/or oxygen content of the fluid. In some examples, the sensed parameters may be used to monitor urine output/rate of urine production of a patient and/or the amount of oxygen dissolved in the urine. Such information may be useful in monitoring the renal function of the patient, e.g., while the catheter is inserted within the patient. In some examples, all or a portion of the sensor(s) may be removably coupled to the catheter body, e.g., such that the catheter body may be disposed after use but all or a portion of the sensor may be reused with another catheter body. For ease of description, examples of the disclosure are primarily described with regard to a catheter such as a Foley catheter being employed as a urinary catheter within a patient. For example, in some instances, the present disclosure is directed to a Foley catheter including one or more sensors configured to facilitate detection and/or quantification of one or more physiological parameters of a patient's urine to determine the urine output of the patient's kidneys (e.g., for renal monitoring). However, examples of the present disclosure are not limited to Foley-type catheters or urinary catheters.

Acute kidney injury (AKI) is a complication that occurs commonly after major surgeries such as cardiac surgery and other operations that are long and involve significant blood loss or fluid shifts. The primary cause of surgery-associated AKI may be hypoxia of the kidneys. Renal hypoxia may cause degradation of renal function, which, after one to three days, e.g., may cause a reduced urine output and/or an accumulation of waste products in the bloodstream. This accumulation of fluid and waste products may delay the recovery of the patient leading to more extended and expensive hospital stays and sometimes requiring renal replacement therapy.

One approach to preventing AKI is to monitor the oxygenation status of a patient's kidneys. However, accurate monitoring may be challenging due to the inaccessibility of the kidneys which are deep in the abdominal cavity. Near-Infrared spectroscopy (NIRS) may measure regional oximetry and may have some utility in infants and slender adults but does not have the depth of penetration and specificity required for most adults.

Systemic vital signs like cardiac output, blood pressure, and hematocrit may be useful but may not always be sufficient to properly monitor the kidneys. When the body becomes stressed, such as during cardiac surgery, blood flow may be reduced to vital organs in a reliable sequence based on the criticality of the organs. It has been observed that the skin may be the first to realize reduced blood flow, followed by the intestines and then the kidneys, then the brain and then the heart. The skin and the intestines may withstand short hypoxic episodes and recover normal function, but the kidneys can be damaged with even brief hypoxic episodes.

Examples of the present disclosure may be related to device features to aid in the monitoring of the kidneys. In some examples, the approach is to monitor the amount of oxygen dissolved in the urine coming from the bladder, as such a measurement may accurately reflects the oxygenation of the kidneys. Such a measurement may be made by monitoring of urine output (rate of urine production) and/or the amount of oxygen dissolved in the urine. Examples of the present disclosure utilize a catheter with one or more sensors that facilitate the determination of such parameters and, thus, allow for the monitoring of the oxygenation status of the kidneys.

As noted above, a Foley catheter may be a type of urinary catheter used in the examples of the present disclosure. A Foley catheter may be modified in the manner described herein to facilitate measurements of urine parameters for renal monitoring. In some examples, one or more sensors may be used in conjunction with a Foley Catheter to monitor renal function to prevent acute kidney injury. In some examples, the sensor(s) may provide data indicating detection of and prevention of acute kidney injury.

FIG. 1is a conceptual side elevation view of an example medical device10, which includes elongated body12, hub14, and anchoring member18. In some examples, medical device10is a catheter, such as a Foley catheter. While a Foley catheter and its intended use is primarily referred to herein to describe medical device10, in other examples, medical device10may be used for other purposes, such as to drain wounds or for intravascular monitoring or medical procedures.

Medical device10includes a distal portion17A and a proximal portion17B. Distal portion17A includes a distal end12A of elongated body12and is intended to be external to a patient's body when in use, while proximal portion17B includes a proximal end12B of elongated body12and is intended to be internal to a patient's body when in use. For example, when proximal portion17B is positioned within a patient, e.g., so proximal end12B of elongated body12is within the patient's urethra and bladder, distal portion17A may remain outside of the body of the patient.

As shown inFIG. 1, elongated body12may be a body extending from distal end12A to proximal end12B and that defines one or more inner lumens. In the example shown inFIGS. 1 and 2, elongated body12defines lumen34and lumen36(shown inFIG. 2). In some examples, lumen34may be a drainage lumen for draining a fluid from a target site, such as a bladder. In other examples lumen34may be used for any other suitable purpose, such as to deliver a substance or another medical device to a target site within a patient. Lumen34may extend from fluid opening13to fluid opening14A. Both fluid opening13and fluid opening14A may be fluidically coupled to lumen34, so a fluid may flow from one of fluid opening13or fluid opening14A to the other of fluid opening13or fluid opening14A through lumen34. In the example where lumen34is a drainage lumen, fluid opening13and fluid opening14A may be drainage openings. In the example shown inFIG. 1, distal end12A of elongated body12is received within hub14and is mechanically connected to hub14via an adhesive, welding, or another suitable technique or combination of techniques.

In some examples, elongated body12has a suitable length for accessing the bladder of a patient through the urethra. The length may be measured along central longitudinal axis16of elongated body12. In some examples, elongated body12may have an outer diameter of about 12 French to about 14 French, but other dimensions may be used in other examples. Distal and proximal portions of elongated body12may each have any suitable length.

Hub14is positioned at a distal end of elongated body12and defines an opening through which the one or more inner lumens (e.g., lumen34shown inFIG. 2) of elongated body12may be accessed and, in some examples, closed. While hub14is shown inFIG. 1as having two arms,14C and14D, (e.g., a “Y-hub”), hub14may have any suitable number of arms, which may depend on the number of inner lumens defined by elongated body12. For example, each arm may be fluidically coupled to a respective inner lumen of elongated body12. In the example ofFIG. 1, hub14comprises a fluid opening14A, which is fluidically coupled to lumen34, and an inflation opening14B, which is fluidically coupled to an inflation lumen36(shown inFIG. 2) of elongated body12. In examples in which anchoring member18does not include an expandable balloon, rather than defining inflation lumen36, elongated body12may define an inner lumen configured to receive a deployment mechanism (e.g., a pull wire or a push wire) for deploying an expandable structure anchoring member18and hub14may comprise fluid opening14A and an opening14B via which a clinician may access the deployment mechanism.

In examples in which medical device10is a Foley catheter, a fluid collection container (e.g., a urine bag) may be attached to fluid opening14A for collecting urine draining from the patient's bladder. Inflation opening14B may be operable to connect to an inflation device to inflate anchoring member18positioned on proximal portion17B of medical device10. Anchoring member18may be uninflated or undeployed when not in use. Hub14may include connectors, such as connector15, for connecting to other devices, such as the fluid collection container and the inflation source. In some examples, medical device10includes strain relief member11, which may be a part of hub14or may be separate from hub14.

Proximal portion17B of medical device10comprises anchoring member18and fluid opening13. Anchoring member18may include any suitable structure configured to expand from a relatively low profile state to an expanded state in which anchoring member18may engage with tissue of a patient (e.g., inside a bladder) to help secure and prevent movement of proximal portion17B out of the body of the patient. For example, anchoring member18may include an anchor balloon or other expandable structure. When inflated or deployed, anchoring member18may function to anchor medical device10to the patient, for example, within the patient's bladder. In this manner, the portion of medical device10on the proximal side of anchoring member18may not slip out of the patient's bladder. Fluid opening13may be positioned on the surface of longitudinal axis of medical device10between anchoring member18and the proximal end12B (as shown) or may be positioned at the proximal end12B.

In accordance with examples of the disclosure, medical device10may include one or more sensors which may be configured to monitor one or more parameters of a fluid within lumen34(FIG. 2) of elongate body12. For example, inFIG. 1, medical device includes sensor20. Sensor20may be configured to sense one or more of a temperature, flow rate, light, fluorescence, oxygen, sound, flow velocity, density or specific gravity of a fluid in elongate body12, e.g., of a fluid within lumen34of elongate body12.

In an example of the present disclosure sensor20may be configured to sense the flow rate of urine or other fluid within elongate body12. For example, as described further below, sensor20may be a thermal dilution sensor with a first temperature sensor (e.g., thermocouple or thermistor) that may sense a first temperature of a fluid at a first location in lumen34, and a second temperature sensor that senses a second temperature of the fluid at a second location in lumen34that is different that the first location on elongate body12, e.g., distal to the first location. Sensor20may also include a heating member configured to heat the fluid within the catheter body at a location between the first and second temperature sensor or a location proximal to both the first and second temperature sensors. The heating member heats the fluid and the temperature sensors record the temperature difference of the fluid between the first and second locations. Sensor20may then determine the flow rate of the fluid within elongate body12based on the sensed temperature difference. For example, the lower the difference in temperature of the fluid between the first and second temperature sensor, the greater the flow rate of the fluid within the elongate body. In some examples, sensor20may be used to estimate or otherwise determine a value of the flow rate of the fluid based on the described thermal dilution technique and/or may be used to determine relative changes in flow by comparing changes in thermal decay between the two temperature sensors over a period of time.

As will be described below, in some examples, the temperature sensor(s) of sensor20used to determine the flow rate of the fluid within elongated body12may also be used for sensing one or more other parameters of the fluid within elongate body12. For example, temperature sensor20may be used in the calibration of an oxygen sensor that uses a fluorescence lifetime material. Oxygen may be sensed using a fluorescence lifetime technique. A fluorescence (or luminescence) material may be exposed to a certain wavelength of light. The fluorescence material may glow or fluoresce when exposed to this wavelength of light. In certain materials, the rate at which the intensity of the fluorescence fades may be inversely proportional to the amount of oxygen in the surrounding fluid. The more oxygen present, the faster the fluorescence fades. By measuring the rate of fluorescence decay, the amount of oxygen can be measured.

Fluorescence material may be temperature-dependent and therefore to obtain a more accurate oxygen measurement it may be helpful to know the temperature of the fluid. The temperature sensed from a thermal dilution flow sensor may be used to calibrate a fluorescence lifetime oxygen sensor. If the oxygen sensor is upstream of the thermal dilution flow sensor, the upstream temperature sensor may be used as the reference for the temperature of the fluid. If the oxygen sensor is downstream of the thermal dilution flow sensor, the downstream temperature sensor may be used as the reference for the temperature of the fluid. Similarly, the flow sensor could be an ultrasonic flow sensor. An ultrasonic flow sensor may also determine the temperature of the fluid and this temperature measurement may be the reference for the temperature of the fluid for the oxygen sensor

Additionally or alternatively, sensor20may be configured to monitor or otherwise determine the flow of a fluid within elongated body12using ultrasonic techniques. For example, sensor20may be an ultrasonic flow sensor including a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within lumen34, and a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within lumen34, where the second ultrasonic sensor may be positioned on the elongated body proximal to the first ultrasonic sensor. In such an example, the first ultrasonic sensor of sensor20may receive the second ultrasonic signal transmitted through the fluid flowing in lumen34. The second ultrasonic sensor of sensor20may receive the first ultrasonic sound transmitted through the fluid flowing in the lumen. By comparing the transit time with the flow and against the flow directions, sensor20may determine an average velocity of the fluid. In some examples, the volumetric flow rate (e.g., measured in ml/min or ml/hour) of the fluid may then be calculated from the flow velocity.

As will be described below, in some examples, when sensor20is in the form of an ultrasonic flow sensor, sensor20may configured as a reusable sensor that may be used with multiple different catheters. For example, one or more components of sensor20may be removably coupled to elongate body12so that those components may be removed from elongated body, e.g., when medical device10is removed from a patient, and then removably coupled to a similar medical device to function in the same or similar manner as an ultrasonic flow sensor. In this manner, one or more relatively expensive components of sensor20may be used with multiple catheters rather than using those components in a single use manner with only one catheter. Ultrasonic sensors may be expensive, and their cost prohibitive to use in a single-use medical device. Further, the ultrasonic flow sensor may also determine the temperature of the fluid and this temperature measurement could be the reference for the temperature of the fluid for the fluorescence lifetime oxygen sensor discussed above.

Additionally, or alternatively, sensor20may be configured to sense or otherwise monitor the composition of a fluid (e.g., the amount or concentration of oxygen within the fluid) within elongated body12using a fluorescence lifetime technique. For example, sensor20may include a fluorescence material that may be located within lumen34, and a light source configured to emit light to expose the fluorescence material to the emitted light. In such a configuration, the fluorescence material within the fluid may fluoresce when exposed to the light in lumen34. Sensor20may also include a light detector configured to detect the fluorescence of the fluorescence material. Sensor20may be configured to detect oxygen in the fluid within lumen34based on the detected fluorescence. For example, the fluorescence material may glow or fluoresce when exposed to the light. The fluorescence material may be platinum octaethylporphyrin (PtOEP), phosphors such as palladium (Pd)-porphyrin, PdTPTBP/PtTPTBP (e.g., palladium(ii)/platinum(ii) tetraphenyltetrabenzoporphyrin); Ir(Cs)2acac (e.g., iridium(iii) bis-(benzothiazol-2-yl)-7-(diethylamino)-coumarin-(acetylacetonate)); and/or Ru-dpp (e.g., ruthenium(ii) tris-4,7-diphenyl-1,10-phenanthroline). In some materials, the rate at which the fluoresce fades is inversely proportional to the amount of oxygen it is exposed to. In such materials, the more oxygen present, the faster the fluorescence fades. By measuring the rate of fluorescence decay, sensor20may accurately measure the amount of oxygen in the fluid flowing within lumen34, e.g., on a periodic or substantially continuous basis over a period of time.

In another example of the present disclosure, sensor20may be configured to sense at least one flow parameter of a fluid within lumen34of elongated body12to allow for medical device10or other device to determine (e.g., via processing circuitry) at least one of a density parameter or a temperature parameter of the fluid in lumen34based on the sensed flow parameter of the fluid. For example, sensor20may be a flow sensor where the flow is calculated by measuring the difference in the transit time of sound traveling against the fluid flow and the transit time of sound traveling with the fluid flow. The difference in the transit times in conjunction with dimensions of lumen34and the constitution of the fluid may be used to calculate the volumetric flow rate of the fluid. In addition, the average transit time of the upstream and downstream sound can be used to calculate characteristics of the fluid; such as temperature and density. By measuring the average transit time in a known geometry (e.g., lumen34), changes in density and temperature can be calculated. For example, the temperature may be measured by a different means (e.g., a thermal dilution flow sensor) and this temperature may be used to calculate the density of the fluid. In another example, the density of the urine may be measured using the average transit time when flow is high and the fluid is assumed to be at body temperature (e.g., 98.6° F.). In another example, body temperature may be measured using a sensor at proximal end12B, from other body temperature measuring devices, or assumed to be normal. The density of fluids, usually represented as the specific gravity, may be an important and common measurement (e.g. urinalysis). For example, the specific gravity of urine can be used to understand a patients' hydration status and the filtration capabilities of patient. The ability to measure urine density continuously and quickly can aid in understanding of the state of patient.

In another example of the present disclosure, sensor20may sense one or more parameters of a fluid within lumen34. Sensor20may require calibration information to be accurate. Flow sensors and oxygen sensors may require sensor-specific calibration information to produce an accurate measurement and compensate for variability in sensor20. Sensor20have memory on sensor20that stores sensor calibration information that is used by external device24to more accurately read sensor data being sent from sensor20. Additionally, or alternatively, memory19may store sensor calibration information to calibrate sensor20based on the sensor calibration information stored by memory19.

Many sensors require calibration information to be accurate. Sensors may provide increasingly accurate measurements with sensor-specific calibration information to compensate for variability in the sensors. For example, a thermal dilution flow sensor may require information that correlates actual flow to measured temperature difference. Variability in the temperature differences may occur due to small differences in the heater member, the thermistors/thermocouples, the lumen dimensions, or the position of the heater elements or thermistors/thermocouples.

Similarly, the fluorescence lifetime oxygen sensor may have calibration parameters related to the fluorescing material used, as well as the specifics of the light source and light detector. Through including the sensor calibration in the sensor or memory19accuracy of the measurement may increase. Further, the ability to change components in a sensor or offer different ranges of sensors in the future without changing the monitoring software may provide flexibility.

In some examples, sensor20may be representative of a single sensor or multiple sensors. Where sensor20may be multiple sensors, the multiple sensors may be located on the elongated body at the same location or at different locations despite being shown at a single location inFIG. 1. Sensor20may communicate sensor data to external device24via an electrical, optical, wireless or other connection. In some examples, sensor20may communicate sensor data to external device24through a connection(s) within elongated body12of medical device10from proximal portion17B to distal portion17A via embedded wire(s) or optical cable(s). In other examples, sensor20may communicate sensor data to external device24via a wireless communication technique.

Sensor20may be positioned on distal portion17A of elongated body12of medical device10including portions of elongated body12positioned distal to distal end12A connected to a fluid collection container (e.g., a urine bag) or the like. Sensor20may be an oxygen sensor utilizing a florescence lifetime technique.

In some examples, sensor20is mechanically connected to elongated body12or another part of medical device10using any suitable technique, such as, but not limited to, an adhesive, welding, by being embedded in elongated body12, via a crimping band or another suitable attachment mechanism or combination of attachment mechanisms. Sensor20may be removably coupled to elongated body12. That is, sensor20may be coupled to elongated body12and used for a procedure and then sensor20may be removed, coupled to another elongated body and used again. In some examples, elongated body12includes a structure distal to a distal end of medical device10, such as tubing extending between hub14and a fluid collection container, which sensor20may be coupled to.

In some examples, sensor20may be disposable and/or reusable. In some examples, sensor20may be disposed of, such as placed into medical waste, when elongated body12is through being used for a medical procedure. In some examples, all or a portion of sensor20may be reusable and detachable from elongated body12so sensor20, or a portion thereof, may be used again on another elongated body for the same, similar or different procedure. For purposes of the disclosure disposable may be defined as an article intended to be used once, or until no longer useful, and then thrown away. Reusable may be defined as an item which can be used again or more than once. A reusable sensor may be configured such that sensor may be coupled to elongate body12so that it functions as described in the examples of the disclosure, subsequently removed from elongate body12and then coupled to another elongate body in a manner that allows the sensor to again function as described herein on the another elongated body.

Sensor20may be configured to communicate sensor data to an external device24. External device24may be a computing device, such as a workstation, a desktop computer, a laptop computer, a smart phone, a tablet, a server or any other type of computing device configured to receive, process and/or display sensor data. Sensor20may communicate sensor data to the external device via a connection26. Connection26may be an electrical, optical, wireless or other connection.

Memory19may be located on elongated body12or hub14. In some examples, all or a portion of memory19may be removable from elongated body12and may be located on or adjacent with sensor20. Data sensed by sensor20may be stored on memory19, e.g., for later retrieval by external device24and/or for processing of the sensor data from sensor20. While memory19is shown as being separate from sensor20, in some examples, sensor20may additionally or alternatively include another memory for storing date from sensor20.

In some examples, memory19may include all or a portion of calibration data for sensor20. Processing circuitry may store sensor data within memory19and communicate this data with external device24. In some examples, medical device10may have processing circuitry on elongated body12or hub14that may control all or some operations of sensor20. In some examples, the processing circuitry of external device24may control all or some operations of sensor20. In some examples, the processing circuitry of external device24and processing circuitry of medical device10may control all or some of operations of sensor20together. Memory19may also store calibration information for sensor20. This calibration information may assist in providing calibration information to sensor20and thus improve the collecting of more accurate information from sensor20. Memory19may also receive information from external device24, which memory19may retain onboard after disconnection from external device24. Further, memory19may then share this information with another external device in the event external device24breaks down or in the more likely event the patient to whom medical device10is inserted into may be moved from surgery to an intensive care. In intensive care, memory19may now communicate with another external device and share information collected from surgery.

Memory19may store program instructions, such as software or algorithms, which may include one or more program modules, which are executable by processing circuitry (not shown inFIG. 1). When executed by the processing circuitry, such program instructions may cause the processing circuitry and external device24to provide the functionality ascribed to them herein. The program instructions may be embodied in software and/or firmware. Memory19may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital media.

Elongated body12may be structurally configured to be relatively flexible, pushable, and relatively kink- and buckle-resistant, so it may resist buckling when a pushing force is applied to a relatively distal portion of medical device10to advance elongated body12proximally through the urethra and into the bladder. Kinking and/or buckling of elongated body12may hinder a clinician's efforts to push the elongated body proximally. Any suitable material may be used for elongated body12, such as a suitable biocompatible polymer or other biocompatible material.

FIG. 2is a diagram illustrating an example cross-section of medical device10, where the cross-section is taken along line1-1inFIG. 1in a direction orthogonal to central longitudinal axis16.FIG. 2depicts a cross section of elongated body12, which defines lumen34and lumen36. In some examples, lumen34may be referred to as a drainage lumen, such as in examples in which medical device10is a Foley catheter configured to drain urine from a bladder of a patient, and lumen36may be referred to as an inflation lumen in examples in which lumen36is configured to deliver an inflation fluid to anchoring member18. Elongated body12may enclose connection38.

Lumen34may serve as a passage for urine entering medical device10through fluid opening13to fluid opening14A. In the example shown inFIG. 2, lumen wall32is relatively non-permeable to substances of interest, such as oxygen and/or carbon dioxide, and positioned between lumen36and lumen34. In some examples, lumen wall32extends along an entire length of lumen34, while in other examples, lumen wall32only extends along only a part of a length of lumen34, for example, from a portion of lumen34intended to be in a patient's bladder during use, which may help maintain a desired level of flexibility of elongated body12. In addition, as shown inFIG. 2, in some examples, lumen wall32extends around an entire outer perimeter of lumen34(e.g., an outer circumference in examples in which the inner perimeter is circular in cross-section).

Inflation lumen36may serve as a passage for a fluid, such as sterile water or saline, or a gas, such as air, from inflation opening14B to anchoring mechanism18. For example, an inflation device (not shown) may pump fluid or gas into inflation lumen36through inflation opening14B into anchoring member18so anchoring member18is inflated to a size suitable to anchor medical device10to the patient's bladder. While inflation lumen36is shown as circular in cross section, it may be of any shape. In some examples, there may be a plurality of inflation lumens. For example, a plurality of inflation lumens may substantially surround lumen34. In some examples, anchoring member18may be an expandable structure not an inflatable balloon. In such examples, inflation lumen36may be replaced by a deployment mechanism which may permit a clinician to expand the expandable structure. For example, inflation lumen may be replaced by a mechanical device pushed and pulled separately from the medical device10by a clinician to expand or retract the expandable structure.

Connection38may serve to connect sensor20positioned at distal portion17A to connection26and/or memory19. Connection38may be an electrical, optical or other connection. In some examples, connection38may comprise a plurality of connections. For example, connection38may include one of more wired or optical connections to a temperature sensor and one or more connections to a pressure sensor. In some examples, connection38may include one or more power connections to power sensor20and one or more communications connections to receive sensor data from sensor20and to receive calibration information from memory19.

In examples of the disclosure, lumen34may have a small diameter35to increase the transit time of the fluid within lumen34. In some Foley Catheters, the drainage lumen cross-sectional area may be maximized to maximize the flow rate. Adult Foley Catheters may be, e.g., 12, 14, or 16 French (e.g., with a drainage lumen diameter of about 1.3 mm to about 2.6 mm). For a given flow rate, as the cross-sectional area increases the transit time of fluid through lumen34decreases. Drainage lumen34may have a relatively small cross-sectional area, e.g., to decrease the flow rate and increase fluid transit time. Through increasing the transit time, physical characteristics of the fluid (e.g., oxygen, temperature, etc.) are preserved which increases the accuracy and utility of measurements. In some examples, diameter35may be about 0.75 mm to about 1.25 mm. A small inner diameter35of lumen34with an increased wall diameter (e.g., thicker walls32) may contribute to the preservation of sensor measurements by also decreasing the gas permeability of elongated body12. Further, the diameter of lumen34may be continuous over the length of elongate body12or it may vary. In some examples, the lumen diameter is tailored based on the location of sensor20, e.g., to increase the accuracy of the measurement by modifying or otherwise controlling the transit time of the fluid relative to the location at which sensor20is sensing the fluid. For example, lumen34may decrease in diameter relative to the location of sensor20so that the transit time of the fluid decreases in the area that sensor20is sensing the fluid. This may be useful with a thermal dilution flow sensor such as that described herein where a decrease in diameter35may increase the effect of heating a flowing fluid and better detect the temperature difference. In some examples, a narrow lumen may expand the diameter at a sensor location on the elongated body of the catheter. This expansion of the diameter may increase sensor sensitivity and accuracy by increasing the time the fluid spends at the sensor location.

FIG. 3is a flowchart illustrating an example operation of medical device10. A clinician may insert proximal end12B of medical device10into a patient's urethra (42). The clinician may advance medical device10through the patient to a target site (44), e.g., until uninflated or undeployed anchoring member18is within the patient's bladder (44). The clinician may connect inflation opening14B to an inflation device and may connect fluid opening14A to a fluid collection container and/or to external sensors (46). The clinician may then deploy anchoring member18to help secure medical device10relative to the target site (48). For example, the clinician may inflate anchoring member18, for example, using an inflation device and inflation fluid, such as sterile water, saline, or a gas. In examples in which anchoring member18is an expandable structure, the clinician may deploy anchoring member18by pushing a structure radially outwards or pulling back on a structure to cause the expandable structure to expand radially outwards.

Lumen34may transport urine from the proximal portion17B of medical device10to the distal portion17A of medical device10(50). Sensor20may sense at least one parameter, such as temperature and/or oxygen, from urine being transported through lumen34(52). For example, sensor20may sense a parameter such as urine flow (e.g., fluid velocity or volume), and/or amount of dissolved oxygen in the urine. In some examples, sensor20may sense at least one parameter between medical device10and a fluid collection container, e.g., at the distal end of elongate body12.

While the example ofFIG. 3, sets forth a number of steps, these steps may be performed in a different order or concurrently. For example, the clinician may connect the inflation opening14B to an inflation device and/or may connect fluid opening14A to a fluid collection container and/or to sensor20prior to inserting the proximal end12B of medical device10into the patient's urethra and lumen34may transport urine concurrently with sensor20sensing any parameters.

FIG. 4is a functional block diagram illustrating an example of an external device24configured to communicate with sensor20, receive information from sensor20and store and retrieve information from memory19. In the example ofFIG. 4, external device(s)24and/or25includes processing circuitry200, memory202, user interface (UI)204, and communication circuitry206. External device(s)24and/or25may be a dedicated hardware device(s) with dedicated software for reading sensor data. Alternatively, external device(s)24and/or25may be an off-the-shelf computing device, e.g., a desktop computer, a laptop computer, a tablet, or a smartphone running a mobile application enabling external device(s)24and/or25to read sensor data from sensor20and memory19.

In some examples, a user of external device(s)24and/or25may be clinician, physician, intensivist, or heath care giver. In some examples, a user uses external device(s)24and/or25to monitor a patient's kidney function, e.g., based on information sensed by sensor20or otherwise derived from information sensed by sensor20in the manner described herein. In some examples, the user may interact with external device(s)24and/or25via UI204, which may include a display to present a graphical user interface to the user, and a keypad or another mechanism (such as a touch sensitive screen) for receiving input from the user. External device(s)24and/or25may communicate with sensor20and/or memory19using wired, wireless or optical methods through communication circuitry206.

Processing circuitry200may include any combination of integrated circuitry, discrete logic circuitry, analog circuitry, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), or field-programmable gate arrays (FPGAs). In some examples, processing circuitry200may include multiple components, such as any combination of one or more microprocessors, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry, and/or analog circuitry.

Memory202may store program instructions, such as software208, which may include one or more program modules, which are executable by processing circuitry200. When executed by processing circuitry200, such program instructions may cause processing circuitry200and external device24to provide the functionality ascribed to them herein. The program instructions may be embodied in software and/or firmware. Memory202may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital media.

FIG. 5is a conceptual and schematic diagram illustrating an example of catheter10including example flow sensor500along a longitudinal cross-section according to an example of this disclosure. Flow sensor500may be an example of sensor20described with regard toFIG. 1. For ease of description, the example ofFIG. 5is described with regard to medical device10ofFIG. 1. However, it is recognized that flow sensor500may be employed in any other type of medical device having a lumen through which a fluid flows to monitor the fluid in the manner described herein via sensor500. For ease of illustration, lumen36is not shown inFIG. 5.

Sensor500is configured to sense the flow rate (e.g., in terms of velocity and/or volumetric flow rate) of fluid504within lumen504of elongated body12. As shown, sensor500may include sensor body514having first temperature sensor502, second temperature sensor508and heating member512. In the example ofFIG. 5, first temperature sensor502is located proximal to second temperature sensor508on elongated body12with heating member512being between first and second temperature sensors502and508. In other examples, heating member512may be located proximal to first temperature sensor502and second temperature sensor508, with first temperature sensor502being proximal to second temperature sensor508. Sensor500may determine a parameter based on the sensed temperatures. Once the determination is made, processor200may control user interface204on external device12to present an indication of the determined value. For example, processor200may control user interface204of the external device to present an indication of a velocity and/or volumetric flow rate determine with flow sensor500.

Sensor body514of flow sensor500may be attached to wall32of elongate body12so that first temperature sensor502, second temperature sensor508and heating member512are adjacent to fluid504within lumen34. In some examples, sensor body514may be releasably coupled to wall32of elongated body12defining lumen34, e.g., so that sensor500may be detached from elongate body12and reused in another catheter such as medical device10. Sensor body514may be releasably connected, e.g., mechanically with latches, snaps, threads, slides, cams, deformable elastic connections, and/or magnetically. Flow sensor500may be located on distal portion17A of elongated body12.

In operation, heating member512may be configured to heat fluid504flowing within lumen34, e.g., via heat conducted from heating member512into fluid504at the location of heating member512on elongated body12. The heat transferred from heating member512into fluid504may create temperature gradient505. Temperature gradient505may be influenced by the flow of fluid504within lumen34. To sense the flow rate of fluid504, first temperature sensor502may sense a first temperature of a fluid504at a first location506in lumen34. Second temperature sensor508may also sense a second temperature (e.g., within temperature gradients505) of the fluid504at a second location510in lumen34that is downstream of first temperature sensor502and heating member512. Sensor500may then determine the flow rate of fluid504based on the difference in the temperature of fluid504sensed by first temperature sensor505and second temperature sensor508. For example, a greater the temperature difference between first temperature sensor502and second temperature sensor508indicates a lesser flow rate of fluid504. For example, a large temperature difference may indicate a lower flow rate and the smaller the temperature difference may indicate a higher flow rate.

First temperature sensor502, second temperature sensor508and heating member512may be located on the other surface of wall32of elongated body12, embedded within wall32of elongated body12, or positioned within lumen34defined by wall34. In some examples, one or more of first temperature sensor502, second temperature sensor508and/or heating member512may be located within lumen34. WhileFIG. 5shows sensor body514and associated components as being located as a discrete circumferential portion of elongated body12, in some examples, sensor body514and/or one or more of the components may substantially surround lumen34of elongated body12. For example, first temperature sensor502, second temperature sensor508and/or heating member512may wrap around lumen34of elongated body12.

First and second temperature sensors502and508may be any suitable sensor capable of sensing the temperature of fluid504within lumen34in the manner described herein. In some examples, temperature sensor502and508are thermocouple sensors or thermistor sensors. Temperature sensors502and508may be micro-electromechanical system (MEMS) sensors, such as MEMS thermocouples and/or thermistors.

Heating member512may be any heating device suitable for heating fluid504within lumen34in the manner described herein, e.g., in a manner that creates temperature gradient505in fluid504flowing within lumen34. In some examples, heating member512may be an electrically resistive element, such as nichrome 80/20 (80% nickel, 20% chromium), Kanthal (FeCrAl), Cupronickel (CuNi), or other materials. Heating member512may heat fluid504as indicated by gradient layers505(including first and second locations506and510) extending outward from heating member512. Heating member512may be located adjacent to lumen34of elongated body12, or within lumen34.

Sensor body514may be comprised of most any material such as is common in printed circuit board design (e.g., FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy)) In another example, sensor body may have a flexible design so it may contour to the cylindrical shape of elongated body10, thus allowing sensors502and508and heating member512to be as close to elongated body12to ensure proper heat transfer and sensor measurements. Flexible PCB materials include PI (polyimide) film and PET (polyester) film apart from which polymer film is also available like PEN (polyethylene nphthalate), PTFE and Aramid etc. In an example, sensor body514may be over molded with silicone, thermoplastic, or other material.

Sensor500may require calibration information to be accurate. Sensor500may require sensor-specific calibration information to produce an accurate measurement and compensate for variability in sensor500. Sensor500may store this calibration information on memory519on sensor20. External device24may use this calibration information to more accurately read sensor data being sent from sensor500. In another example, memory19may store sensor calibration information to calibrate sensor500based on the sensor calibration information stored by memory19.

Temperature sensors502and508, heating member512and sensor body514may all be separate components, or they may all be part of the same body, such as, all components being a part of sensor body514or all part of elongated body12. Each of temperature sensors502and508, heating member512and sensor body514may be integral with elongated body12or each component may be coupled to elongated body12together on sensor body514or separately.

First temperature sensor502, second temperature sensor508, and heating member512may have any suitable spatial arrangement on elongated body12. In some examples, heating member512is located proximal to both first temperature sensor502and second temperature sensor508on elongated body12. In other examples, heating member512is between first temperature sensor502and second temperature sensor508, with first temperature sensor502being located proximal to heating member512on elongate body12. In some examples, temperature sensors502and508may be about 2 mm to about 20 mm apart from each other on elongated body12although other values are contemplated. The distance between first and second temperature sensors502and508may be selected such that there is at least some thermal decay in the fluid (temperature change) between the locations of first and second temperatures sensors502when fluid504is flowing at flow rates of interest.

In some examples, the distance between temperature sensors502and508may be predetermined and/or stored in memory519, memory202or memory19. In some examples, the distance between temperature sensors502and508may constitute sensor calibration data that is used by processing circuitry200or other processing circuitry to calibrate sensor500. In some examples, sensor500may include memory519that stores such calibration data for calibration of sensor500, e.g., in cases in which sensor500is removably coupled to elongated body12so that sensor500may be calibrated and used on multiple different catheters.

As described above, first temperature sensor502may be located proximal of heater member512on elongated body12. In some examples, first temperature sensor502is located at a proximal position on elongated body12relative to heating member512where the temperature of fluid504is not substantially changed by heater member512when heating member512heats fluid504. In other examples, first temperature sensor502is located at a proximal position on elongated body12relative to heating member512where the temperature of fluid504is influenced (e.g., changed) by heating member512when heating member512heats fluid504(e.g., first temperature sensor502senses the temperature of fluid504within temperature gradient505). In some examples, first temperature sensor502may be located distal to heating member512at a location where the temperature of fluid504is influenced by heating member512when heating member512heats fluid504. In some examples first temperature sensor502may be located downstream or distal of second temperature sensor508where the heat transferred by heating member512has dissipated and fluid504is assumed to be near room temperature.

Second temperature sensor508may be located distal to both first temperature sensor502and heating member512, and may be at a position on elongated body12within temperature gradient505, e.g., as compared to a location at which the temperature of fluid504is not changed by heating member512when fluid504is heated. In some examples, when fluid504is not flowing in lumen34, second temperature sensor508may measure a temperature at second location510which is substantially the same as the temperature of fluid504directly adjacent to heater member512. The flow rate of fluid504may change the temperature difference between first and second sensors502and508, e.g., where a change in flow rate of fluid504results in a change in the temperature difference of fluid504sensed at first location506and second location510by temperatures sensors502and508, respectively.

FIG. 6is a flow diagram illustrating an example technique for monitoring or otherwise sensing a flow rate of fluid504within lumen34using sensor500. Processor circuitry200may be used to calculate a flow rate determination of fluid504and the technique ofFIG. 6will be described as such for ease of description. However, processing circuitry on medical device10, elongated body12, and/or other device may be used to make the flow rate determination.

As shown inFIG. 6, heating member512may heat fluid504, e.g., as fluid504flows from proximal end17B to distal end17A of elongated body12within lumen34heating member (602). In some examples, a user may begin a monitoring process at external device24. Upon initiation of a monitoring process at external device24, processing circuitry200may initiate the sensing process for flow sensor500. This may include providing power to heating member512to begin heating fluid504. This may include external device24requesting a verification through user interface204fluid504is currently flowing through lumen34. In another example, processing circuitry200may not apply power to heating member512until fluid504is within lumen34. Thus, heating member512is not applying heat directly to lumen34without any fluid504to dissipate the heat and possibly cause melting of lumen34. Processing circuitry200may also supply power to first temperature sensor502and second temperature sensor508(e.g., if temperature sensor502and temperature sensor508require a power source). In some examples, flow sensor500may have a power switch and an onboard power supply to power heating member512. A user may power on the flow sensor500when the flow sensing process begins or when fluid504begins flowing through lumen34.

Heat transferred from heating member512to fluid504, indirectly or directly, may heat fluid504adjacent to heating member512to generate temperature gradient505within fluid flow504. In some examples, heating member512may increase the temperature of fluid504at least 0.01 degrees Celsius, such as a maximum temperature increase of about 0.01° C. to about 5° C. within lumen34. Heating member512may operate substantially continuously to generate gradient505within fluid504(e.g., to allow for substantially continuous monitoring of the flow rate of fluid504) or periodically (e.g., to allow for periodic sampling of the flow rate of fluid504).

First temperature sensor502at first location506may sense a first temperature of fluid504, e.g., while heating member512is heating fluid504or shortly thereafter (604). As described above, depending on the location of first temperature sensor502relative to heating member512, the temperature of fluid504may or may not be changed by the heating of fluid504via heating member512. Second temperature sensor518, located at second location510, may sense a second temperature of fluid504, e.g., while heating member512is heating fluid504or shortly thereafter (606). The temperature of fluid504at second location510may be increased by the heat transferred to fluid504via heating member504. As described herein, as a result of the flow of fluid504within lumen34, there may be a temperature difference of fluid504between first location506and second location510. This temperature difference may change based on the flow rate of fluid504and, thus, allows sensor500to sense the flow rate of fluid504(e.g., in terms of a flow rate value and/or change in flow rate over a period of time).

Processing circuitry200may determine the difference in the first temperature of fluid504sensed by first temperature sensor502and the second temperature of fluid504sensor by second temperature sensor508(608). Processing circuitry200may then determine a flow rate of fluid504based on the difference in temperature between first sensed temperature and the second sensed temperature (610). For example, processing circuitry200may determine a flow rate value that corresponds to the determined temperature difference (e.g., based on preprogrammed values stored in a lookup table or other data structure, or a preprogrammed modeling on the fluid flow within lumen34) and/or may identify trends over time with or without regard to the actual flow rate value (e.g., by identifying changes in temperature difference that correspond to an increase or decrease in flow rate over the period of time). Processing circuitry200may be configured to sample the temperature difference substantially continuously or periodically (e.g., based on a preprogrammed schedule or input from a user indicating that a flow rate of fluid504should be determined). Processing circuitry200may determine a correlation between the change in temperature of fluid504through sensor500and the flow rate may depend on many variables which may be considered with calibration information stored on memory519, memory19and/or memory202. The calibration information may include manufacturing variances and tolerances of sensor500. The calibration information may also include the dimensions of lumen34, the exact position of first temperature sensor502and second temperature sensor508and heating member512, as well as the constitution of fluid504, such as bubbles, thermal conductivity, thermal capacity. Values like the unique characteristics of first temperature sensor502and second temperature sensor508and lumen34may be measured during manufacturing. In some examples, the constitution of fluid504may be assumed unless otherwise measured.

In some examples, processing circuitry200may control user interface204to display the determined flow rate to a user (e.g., operator, clinician, intensivist, surgeon or physician) to observe. Further, as will be described below, processing circuitry200may use the flow rate to calculate density, urine output, and/or other parameter of fluid504and display these parameters to the user. In some examples, processing circuitry may generate an alarm displayed via user interface204, sound an alarm audibly through a speaker (not shown inFIG. 4) or utilize another user interface based on a determination that the flow rate has changed more or less than a threshold amount (e.g., when the increase or decrease is indicative of impaired kidney function or increased risk of AKI). In another example, processing circuitry may determine there is no flow (e.g., such as no temperature difference between first temperature sensor502and second temperature sensor508) or even a back flow condition where the sensed temperature at first temperature sensor502is greater than the temperature at the second temperature sensor508.

Flow sensor500may be used to measure flow rates in the range of nanoliters to microliters per minute although other values are contemplated. Processing circuitry200may use any suitable processing technique to determine the flow rate based on the temperature difference. Processing circuitry200may determine a total flow volume utilizing a flow rate, known dimensions of lumen34and a change in time during a procedure. Memory202(FIG. 4) may store software208, an algorithm or a lookup table of the fluid's constitution (e.g., specific heat, density, specific gravity, etc.) that processing circuitry may use to determine various parameters of fluid504. In another example, an operator may enter specific fluid types before use of medical device10or memory202may have come preloaded with values for fluids based on the targeted use of medical device10(e.g., urine in the case of a urinary catheter such as a Foley catheter). In another example, flow sensor500may have onboard processing circuitry that may correlate a flow rate based on sensor data collected from first temperature sensor502, second temperature sensor508and heating member512. For example, processing circuitry200may determine a temperature difference of “X”. Processing circuitry200may access a lookup table, stored in memory202, defined for a particular diameter lumen, the fluid within the lumen and determine the flow rate corresponding to the measured temperature difference X. In another example, an algorithm or software208may model the flow within the system specific to diameter35, fluid heat capacity and/or the like and use temperature difference as an input that generates a flow rate output.

In one example, external device24receives temperature data from temperature sensors508and502for use in a thermal dilution algorithm to determine a flow rate of fluid504. Heating member512may have first and second temperature sensor502and508on either side of heating member512. Heating member512may heat fluid504and first and second temperature sensors502and508record the temperature of fluid504both upstream by first temperature sensor502and downstream of heater member512by second temperature sensor508. The greater the difference in temperature, the slower the flow rate of fluid504and the lesser the difference in temperature, the faster the flow rate of fluid504. In some examples, memory519may contain calibration data that processing circuitry200or another processing circuitry may reference to obtain a more accurate information regarding the lumen diameter, thermal characteristics of fluid504and temperature difference.

In some examples, the determined instantaneous volumetric flow rate may be determined over time to determine a total volumetric flow per unit of time or total fluid output. This measurement may be very useful to clinicians and may be expressed in ml/min or ml/hour and sometimes normalized to a patient's weight to ml/hr/kg

FIG. 7Ais a diagram illustrating an example oxygen sensor701used with a medical device10according to the techniques of this disclosure. Oxygen sensor701may be an example of sensor20of medical device10(FIG. 1), may be used in place of sensor20, used in combination with sensor20or sensor500or in addition to sensor20and sensor500.

Oxygen sensor701may be configured to determine an oxygen level within fluid504utilizing, e.g., a fluorescence lifetime technique (FLT). Oxygen sensor701includes sensor body712housing a light source704, a light detector710, an optional lens714and a fluorescence material702. Sensory body712may support light source704, light detector710and optional lens714. Sensor701may determine a parameter based on the sensed fluorescence. Once the determination is made, processor200may control user interface204on external device12to present an indication of the determined value. For example, processor200may control user interface204of the external device to present an indication of oxygen saturation of fluid504determined with oxygen sensor701.

In one example, sensor701is configured to sense oxygen in fluid504(e.g., oxygen concentration) using a FLT. In this technique, fluorescence material702is exposed to light706(which may be a specific wavelength) emitted from light source704. Fluorescence material702(referred to as a fluorescence lifetime material or an optrode), glows (fluoresces708) when exposed to this light. In specific materials used for fluorescence material702, the rate at which the glow fades is inversely proportional to the amount of oxygen it is exposed to. In these materials, the more oxygen is present the faster the glow fades. By measuring the rate of glow decay in calibrated optrodes with light detector710, sensor701may measure the amount of oxygen in fluid504, e.g., accurately and/or substantially continuously.

For use in a Foley catheter or other catheter, in some examples, fluorescence material702may needs relatively small, e.g., to fit within lumen34without substantially obstructing the flow for fluid504. The fluoresces of the fluorescence material702may not be very intense and therefore light detector710(referred to in some examples as a photodiode) may needs to be relatively high-performance, which may be expensive and large. To overcome these limitations, in some examples, fluorescence material702may be disposable and within the drainage lumen34of the Foley catheter or other catheter, but the light source704and light detector710may be reusable and detachably coupled to elongated body12. In addition, option lens714may be configured to gathers the fluorescence708from fluorescence material702and focusses light716on light detector710to increase its intensity and/or reduce the performance requirement of light detector710. In some examples, lens714may additionally, or alternatively, focus the excitation light706emitted from the light source704. As illustrated inFIG. 7B, in some examples, lens714may be a part of the disposable portion of sensor701. Alternatively, lens714may be on the re-usable portion of sensor701(e.g., in addition to light source704and/or light detector710). As described below, lens714may have one or more filters to improve the delivery of the excitation light706from light source704and/or sensing of the fluorescent light716by light detector710. In other examples, sensor701does not include lens714.

As described herein, oxygen sensor701may be an optical sensor device that optically measures a specific substance (e.g., oxygen in fluid504) with the aid of a fluorescence material702(which may be referred to as an optode or optrode). For FLT, e.g., oxygen sensor701may utilize luminescence (e.g., fluorescence and phosphorescence) or chemiluminescence to measure the oxygen within fluid504within lumen34. However, other methods of optical measurement may be used. In some examples, optical sensing techniques such as reflection, absorption, evanescent wave, surface plasmon resonance, may be used.

Fluorescence material702may be any suitable material configured to fluoresce in response to being exposed to light716from light source704in the manner described herein. In some examples, fluorescence material702may include, e.g., platinum octaethylporphyrin (PtOEP), phosphors such as palladium (Pd)-porphyrin, PdTPTBP/PtTPTBP (palladium(ii)/platinum(ii) tetraphenyltetrabenzoporphyrin); Ir(Cs)2acac (iridium(iii) bis-(benzothiazol-2-yl)-7-(diethylamino)-coumarin-(acetylacetonate)); and/or Ru-dpp (ruthenium(ii) tris-4,7-diphenyl-1,10-phenanthroline), white phosphorus, nitric oxide, fluorophores and fluorophore derivatives, such as of rhodamine, coumarin and cyanine. When exposed to excitation light506, fluorescence material702releases fluorescence708. Fluorescence708of fluorescence material702may be quenched, or caused to dissipate, by specific analytes oxygen) in fluid704. The fluorescence708to oxygen ratio within fluid504may not be linear. Oxygen sensor701may have a greater sensitivity at low oxygen concentration, (e.g., when the fluorescence708is the greatest) then at high oxygen concentration (e.g., when the fluorescence708is the lowest). Nevertheless, oxygen sensor701may operate in a region of 0-100% oxygen saturation in fluids containing mostly water, such as urine, with a calibration for the type of material reacting with fluorescence material702.

Light source704may be any suitable light device configured to emit light706in the manner described herein. In some examples, light source704includes an LED (light emitting diode), amplified natural lighting, HID (high-intensity discharge) and/or fluorescent and incandescent source capable of emitting light706, e.g., at an excitation wavelength. Light source704emits a wavelength of light which excites the fluorescence material702. The wavelength of light may be different for differing fluorescence material702(e.g., different fluorescence material chemistries have different excitation frequencies). Light source704may be powered by an onboard power source on oxygen sensor701or maybe powered by external device24providing power through connection38(FIG. 2). In some examples, light source704may emit a specific wavelength of light, that causes fluorescence material702to enter an excited state. FLT may be the time fluorescence material702spends in the excited state (Tes). In some examples, the FLT may vary from picoseconds to hundreds of nanoseconds depending on fluorescence material702. FLT may not depend on fluorescence concentration, absorption by fluid504, thickness of fluid504, method of measurement, fluorescence intensity, photo-bleaching and/or excitation intensity. However, FLT may be affected by external factors, such as temperature (discussed below, which may be calibrated for), polarity, and the presence of fluorescence quenchers (e.g., oxygen).

Light detector710may be any type of light detector configured to detect fluoresced light716from material702, e.g., to detect the decay of light716from material702over a period of time. In some examples, light detector710may be a photodiode (e.g., PN photodiodes, PIN photodiodes, avalanche photodiodes (particularly well suited for fluorescence sensor due to their high sensitivity), and Schottky photodiodes), photoconductor (e.g., photoresistor), photovoltaic device (e.g., photocell), phototransistor, and/or photodiode. Light detector710may detect light excitation between 300 nm and 800 nm. Light detector710may detect the light excitation of fluorescence708. In some examples, processing circuitry200may process the light excitation data of light detector710to detect the time fluorescence708spends in the excited state or otherwise detect the rate of decay of fluorescence708.

Lens714may be configured to focus light706emitted from light source704to fluorescence material702and/or focus fluorescence708to light detector710(as represented by light716). In some examples, lens714may be optical glass, crystals, plastics, mirrors or other material that focuses light in the manner described herein. Lens714may focus fluorescent light716on light detector710to increase its intensity and reduce the performance requirement of light detector710. Lens714may also focus light706from light source704onto fluorescence708. Lens714may be configured to be disposable or re-usable as part of sensor701. In some examples, lens714may also have filters to optimize the delivery of excitation light706or sensing of fluorescence light716. With filters, light source704and light detector may not need to be so precise and thus less expensive alternatives for light source704and light detector710may be used. By filtering excitation light706being emitted onto fluorescence708and filtering fluorescence light716being detected by light detector710, both light source704and light detector710may not necessarily need to be very high performing devices and thus may be less expensive.

Sensor body712may be configured to house, support or otherwise couple together one or more of light source704, light detector710, or lens714, e.g., in a desired arrangement. In some examples, sensor body712may be configured to be removably coupled to elongated body12, e.g., to allow for a portion of sensor701to be reusable with other catheters (e.g., as shown inFIG. 7B).

In some examples, sensor body712may include a material that is used imprinted circuit board design (e.g., FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy). FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1. (cotton paper and epoxy), CEM-2 (cotton paper and epoxy)). In another example, sensor body712may have a flexible design so it may contour to the cylindrical shape of elongated body12, thus allowing lens714, light source704and light detector710to be as close to elongated body12as possible to ensure reliable light transfer and sensor measurements. Flexible PCB materials include PI (polyimide) film and PET (polyester) film apart from which polymer film is also available like PEN (polyethylene nphthalate), PTFE and Aramid etc.

Sensor701may require calibration information to be accurate. Sensor701may require sensor-specific calibration information to produce an accurate measurement and compensate for variability in sensor701. Sensor701have memory719on sensor701that stores sensor calibration information that is used by external device24to more accurately read sensor data being sent from sensor701. In another example, memory19may store sensor calibration information to calibrate sensor701based on the sensor calibration information stored by memory19.

In FLT, fluorescence material702may be located within lumen34with fluid504on an opposite side of lumen34from lens714, light source704and light detector710. Medical device10may come with fluorescence material702within lumen34or fluorescence material702may be inserted in a separate procedure before use of medical device10. When powered on, by processing circuitry200or a separate power source onboard (not shown) light source704may emit light706, e.g., at a specific wavelength to expose fluorescence material708to emitted light706. Light source704may emit light706through elongated body12. In some examples, elongated body12is transparent to emitted light706or otherwise configured to allow light706to be transmitted through elongated body12to fluorescence material702.

Fluorescence material702within fluid504, as discussed above, may be configured to fluoresce708when exposed to light706in lumen34. Light detector710may detect fluorescence708of fluorescence material702. Processing circuitry220may then determine the amount of oxygen within fluid504by recording the time for fluorescence708(Tf) to quench (or dissipate) or otherwise decay. Processing circuitry200may then determine the time to dissipate (Tf) with (Tes) and based upon this difference, determine how much oxygen is present within fluid504. Further, processing circuitry such as processing circuitry200may calibrate for the temperature of fluid504, which may have an effect on how quickly fluorescence708dissipates.

In another example, fluorescence material702may be excited with light pulses (e.g., light initiated in a sine wave pulse). Processing circuitry200may then determine a frequency shift of the fluorescence material response that measures the fluorescence decay time continuously. In another example, when fluorescence material702is excited the fluorescence saturation time may be measured and determined by processing circuitry200, where the saturation time is proportional to oxygen content.

In some examples, light source704and light detector710are releasably coupled to elongated body12, e.g., either separate from each other or together via the detachment of sensor body712from elongated body12as shown inFIG. 7B. In other examples, each of light source704and light detector710may be part of or integral with elongated body12or may be separate and coupled to elongated body12for use during a procedure. In some examples, sensor body712may be releasably coupled to elongated body12as shown inFIG. 7Bwhere sensor body712may support light source704and light detector710. In some examples, sensor body712may be part of or integral with elongated body12. In some examples, lens714may be added if necessary, for improved performance of light source704and light detector710and may be placed on elongated body12in between fluorescence material702and light source704. Lens714may be used to focus light706to fluorescence material702in lumen34. Lens714may focus fluorescence708from fluorescence material702to light detector710. In some examples, lens714may be disposed of along with elongated body12and fluorescence material702when the patient no longer needs medical device10.

Processing circuitry200may use time for fluorescence708(Tf) to determine an amount of oxygen within fluid504within lumen34. As discussed, fluorescence708has an excitation limit (Tes) which exists outside of factors which may shorten this time period. One of these factors is the amount of oxygen present within fluorescence708. Oxygen will cause fluorescence708to decay or quench faster than normal. Fluorescence708excitation time (Tf) may be at a maximum when there is no oxygen present. Thus, when no oxygen is present fluorescence time (Tf) equals or is substantially close to fluorescence excitation time (Tes) with all other variable the same (e.g., such as temperature). When an oxygen is present in fluid504and collides with fluorescence708, this quenches the fluorescence708. If fluid504has no oxygen present, then fluorescence time (Tf) should be close to or equal to the excitation state time (Tes). On the other hand, if fluid504has a 100% oxygen saturation, then fluorescence time (Tf) should be zero or substantially zero. As stated above, the relation to fluorescence time (Tf) and oxygen concentration may be non-linear. Therefore, processing circuitry200may use an algorithm to determine the amount of oxygen within fluid504. In another example, processing circuitry200may utilize a lookup table stored on member202or memory719, memory19, where an oxygen content of fluid504is dependent on fluorescence time (Tf) and the temperature of fluid504(e.g., discussed above, temperature also affect fluorescence time).

For use with medical device10, oxygen sensor701may be relatively small (e.g., 0.25 mm×0.25 mm and as large as 20 mm×20 mm). Fluorescence708may not be very intense and therefore light detector710may be a high-performance light detector710. High-performance light detectors may be expensive and large. Thus, light source704may be reusable and light detector710may be reusable and may be located on a sensor body712and removed from elongated body12when a procedure is complete.

In another example, lens714may be used to focus fluorescent light716on light detector710to increase light intensity and reduce the performance requirement and thus cost of light detector710. Lens714may also focus light706from light source704onto fluorescent material702. Lens714may be part of disposable elongated body12of medical device10, but it may also be located on sensor body712. In another example, lens714may also have filters which filter out all light except the specific wavelength of excitation light706. Further, the filters may filter wavelengths of fluorescent light716so only fluorescent light716is reflected onto light detector710. Lens714may make it possible to use less expensive light sources704and light detectors710. Thus, in some examples, light sources704, light detectors and lens714may be disposable after use.

As discussed above, the accuracy of oxygen sensor701may be temperature dependent as temperature affects the fluorescence time (Tf). Thus, to provide accurate sensor readings, sensor701may be calibrated, e.g., in real time, to obtain an accurate oxygen measurement. To obtain this measurement the temperature of fluid504may need to be known. Therefore, the more accurately the temperature of fluid504is known, the more accurate a reading of oxygen can be obtained from sensor701.

In an example of the present disclosure, a temperature reading may be obtained from sensor500(FIG. 5), memory719, memory circuitry19, memory202or another suitable component, and used to calibrate sensor701. For instances when elongated body includes both sensor500(FIG. 5) and sensor701, the temperature of fluid504may be determined via first temperature sensor502and/or second temperature sensor508. In configurations in which sensor701is upstream/proximal of sensor500, e.g., first temperature sensor502may be used as the reference for the temperature of fluid504. In configurations in which sensor701is downstream/distal of sensor500, second temperature sensor508may be used as the reference for the temperature of fluid504. In other examples, first temperature sensor502or second temperature sensor508may be used to determine the temperature of fluid504within lumen34regardless of the location of sensor701for use in calibrating the oxygen sensing carried out by sensor701. Further, flow sensor500may assist in a better understanding of the dissolved oxygen measurement of sensor701. In an example, a low volumetric flow rate may mean the dissolved oxygen measurement of sensor701may not be as accurate to renal oxygenation due to the effects of the ureter, bladder, and slow transit time through lumen34. Thus, an alert may be sent to user interface204, providing an indication the sensed oxygen may be inaccurate due to low volumetric flow.

Processing circuitry200may use the temperature data collected from temperature sensor502, temperature sensor508, an estimated temperature based on a patient's body temperature, another sensor coupled to external device24or a temperature inputted by a user at user interface204. Processing circuitry200may use the temperature to input into, e.g., an algorithm or a look up table to calibrate the oxygen calculation based on temperature of fluid504in combination with the rate of fluorescence decay detected by light detector710.

FIG. 8is a flow diagram illustrating an example technique for monitoring or otherwise sensing oxygen within a fluid using sensor701ofFIG. 7Aaccording to techniques of this disclosure. Processing circuitry200may control light source704to emit light706to expose fluorescence material702within fluid504to light706in lumen34(802). In some examples, oxygen sensor701may be a stand-alone sensor having its own processing circuitry to control light source704to emit light706onto fluorescence708that is emitted from fluorescence material702when contacted by fluid504in lumen34.

As discussed above, light source704may be powered by external device12through connection38or light source704may be powered by a power source (not shown inFIG. 7A or 7B) onboard oxygen sensor701. Light source704is shown outside of elongated body12and emitting light706through elongated body12into lumen34. In some examples, where elongated body is made of an opaque material, light source704may be embedded within elongated body12and closer to lumen34to help light source704emit light706into lumen34. In some examples, oxygen sensor701my use a light source704emitting light706at wavelengths capable of penetrating material oblique to other wavelengths of light. In other examples, light source704may be located within or partially within lumen34so light706may contact fluorescence708.

Light detector710may be located outside of elongated body12as shown inFIGS. 7A & 7B. In other examples, such as where elongated body12has an opaque material, light detector710may be located within or partially within elongated body12so light detector10may receiving fluorescence716. In some examples, light source704and light detector may be embedded within elongated body12where light source704and light detector710may be placed closer to lumen34, but still not within lumen34to allow for better emitting of light706and detection of fluorescence light716.

Light detector710may detect fluorescence708of fluorescence material702(804). Based on detected FLT (Tf), processing circuitry200may determine an amount oxygen in fluid504within lumen34. The greater the amount of oxygen present the lower the amount of fluorescence708detected and the lower the amount oxygen the higher the amount of fluorescence708detected. For example, in some instances, processing circuitry200may determine a concentration of oxygen in fluid504. Processing circuitry200may continually monitor light detector710sensing the FLT (Tf). Based upon Tfprocessing circuitry may utilize a lookup table or an algorithm to determine an oxygen level within lumen34. Further, processing circuitry200may determine an oxygen level at a specific point in time, or a running average of oxygen amount or even determine a trend of oxygen with lumen34over time.

In some examples, lens714may focus emitted light706through lens714, e.g., to fluorescence material702. Additionally, or alternatively, lens714may also focus fluorescence708from fluorescence material702to light detector710. Lens714is shown inFIG. 7Aas being located outside of elongated body12. In some examples, elongated body12may have a thinner wall at a location for sensor701so lens714may be located closer to lumen34and amplify light706and fluorescence light716. In another example, lens714may be a thin lens with curvature placed within or integral with lumen34. In some example, lens714may be located between elongated body12and light source704and light detector710, where light source704and light detector710are lower end devices requiring the amplification lens714provides to both amplify light706and fluorescence716.

As described above, processing circuitry200may determine a temperature of fluid504within lumen34as part of the determination of the oxygen in fluid504(806). Fluorescence material702may be temperature-dependent and therefore to obtain a more accurate oxygen measurement the temperature of fluid504may be useful in calibrating the oxygen measurement. Processing circuitry200may use the temperature data collected from temperature sensor502, temperature sensor508, an estimated temperature based on a patient's body temperature, another sensor coupled to external device24or a temperature inputted by a user at user interface204. Processing circuitry200may use the temperature to input into, e.g., an algorithm or a look up table to calibrate the oxygen calculation based on temperature of fluid504in combination with the rate of fluorescence decay detected by light detector710.

Any suitable technique may be employed by processing circuitry200to determine the level of oxygen in fluid504based on the fluorescence detected by light detector710. In some examples, processing circuitry200may reference a look up table in memory202to determine the oxygen level within fluid504based upon the detected fluorescence (e.g., alone or in combination with the determined temperature). In some examples, processing circuitry200may execute an algorithm on memory202which calculates the oxygen level based upon the fluorescence708detected or the fluorescence708and the determined temperature of fluid504. In some examples, processing circuitry200may reference a lookup table stored in memory719, memory202or memory19. The lookup table may have a correlation for a specific fluorescence material702and what the fluorescence material's fluorescence time (Tf) is based upon a determined temperature of fluid504. Based upon the temperature of fluid504and the fluorescence time (Tf) sensed by light detector710a lookup table may provide a corresponding oxygen level of fluid504based on the known variables. In another example, a lookup table may be implemented in algorithmic form where the variables are inputted into the algorithm by processing circuitry200and an oxygen level is presenting in display form on user interface204and/or through an audible form by a speaker on external device24. In some examples, an alarm may be implemented through user interface204visually and/or audibly through a speaker if the oxygen level deviated outside of an upper or lower threshold. In another example, processing circuitry200may execute software208to perform the oxygen level determination based upon fluorescence time (Tf) and/or temperature calibration process ofFIG. 8.

FIG. 9Ais a diagram illustrating an example ultrasonic flow sensor901used with medical device10according to the techniques of this disclosure. Ultrasonic flow sensor901may be an example of sensor20of medical device10(FIG. 1), may be used in place of sensor20or sensor500, used in combination with sensor20, sensor500or701or in addition to sensor20, sensor500and sensor701.

Ultrasonic sensor901may be configured to determine a flow rate of fluid504utilizing, e.g., a transit time technique or other technique described herein. Ultrasonic sensor901may include sensor body912, first ultrasonic sensor930, and second ultrasonic sensor934. In some examples, sensor body912houses and/or couples first ultrasonic sensor930and second ultrasonic sensor934to each other, e.g., in a fixed position, on elongated body12of medical device10. The term “ultrasonic” may refer to a signal (e.g., in the form of a sound wave) having a frequency above the approximate upper limit of human hearing, e.g., at or about 20 KiloHertz (KHz). Sensor901may determine a parameter based on the sensed transit times. Once the determination is made, processor200may control user interface204on external device12to present an indication of the determined value. For example, processor200may control user interface204of the external device to present an indication of a velocity and/or volumetric flow rate determine with flow sensor901.

As will be describe further below, first and second ultrasonic sensors930,934may each be configured to transmit signals (e.g., sound waves such as ultrasound waves) through fluid504as fluid504moves through lumen34of elongated body12. For example, as shown inFIG. 9A, first ultrasonic sensor930may transmit first ultrasound waves932(or first signals932) through fluid504and second ultrasonic sensor934may transmit second ultrasound waves936(or second signals936) through fluid504, e.g., in an opposite direction from that of the direction of first sound waves932. First and second ultrasonic sensors930and934may receive the sound wave transmitted by the other of sensor930and934, as well as transmit their respective sound waves. Put another way, first and second ultrasonic sensors930and934may each function as signal transmitters and signal receivers.

As shown inFIG. 9A, first and second ultrasonic sensors930,934may be positioned such that first and second ultrasound waves932and936, respectively, are transmitted substantially completely along the direction of flow of fluid504within lumen34(e.g., substantially parallel with the flow direction of fluid504and/or substantially parallel to the longitudinal axis of lumen34). In other examples, first and second ultrasonic sensors930,934may be positioned such that first and second ultrasound waves932and936, respectively, are transmitted partially in the direction of the flow of fluid504(e.g., at a non-parallel angle to the direction of the flow of fluid504and/or the longitudinal axis of elongated body12).

In some examples, first ultrasound sensor930may transmit first sound waves932in a path substantially parallel to the flow direction of fluid504in lumen34but in the opposite direction, and second first ultrasound sensor934may transmit second sound waves936in a path substantially parallel to the flow direction of fluid504in lumen34and in the same direction as the fluid flow. The first and second sound waves932,936may be transmitted at substantially the same time or sequentially with each other. First sound waves932may be received by second ultrasound sensor934and the second sound waves936may be received by first ultrasound sensor930. By comparing the transit time of second sound waves936with the flow of fluid504and the transit time of the first sound waves932against the flow of fluid504, the average velocity of fluid504may be determined, e.g., by processor200. From the average velocity, the flow rate of fluid504may be determined, e.g., by processor200. In addition to, or as an alternative to, using transit time, ultrasonic sensor901may use frequency shifts to measure velocity and/or flow of fluid504.

In some examples, ultrasonic sensors such as sensor930and934, may be relatively expensive and, thus, cost prohibitive to use in a single-use medical device such as a single use catheter. In accordance with some examples of the disclosure, ultrasonic sensor901may be employed with medical device10(e.g., in the form of a Foley catheter system) such that sensor901or at least some components thereof are re-usable and not a non-separable part of a single-use catheter. Rather, as shown inFIG. 9B, sensor901may be detached from elongated body12and may be reused as to sense the flow of a fluid in another catheter while medical device10may be disposed after use with a single patient.

First930and second ultrasound sensors934may be any suitable receiver and/or transmitter configured to function in the manner described herein. In some examples, sensor930and934may include an ultrasonic transducer/transceiver such as linear, convex (standard or micro-convex), and phased array which are capable to transmitting and receiving ultrasonic sound waves. In some examples, first ultrasonic sensor930and second ultrasonic sensor934may be ultrasonic diffuse proximity sensors that employ a sonic transducer that allows for alternate transmission and reception of sound waves. The transducer may emit a series of ultrasonic pulses and then “listen” for an ultrasonic signal. Once the ultrasonic signal is received, ultrasonic sensor930and/or934signals an output to a control device such as a processing circuitry200or onboard processing circuitry (not shown inFIG. 9A or 9B). Ultrasonic sensors930and/or934may have their sensitivity, defined as the time window for “listen” cycles versus “send” cycles, adjusted via a teach-in button or a potentiometer. This output can easily be converted into useable distance information.

Ultrasonic sensors930and934may be power by any suitable power source, such as an onboard power source on ultrasonic flow sensor901or maybe powered by external device24providing power through connection38(FIG. 2).

In some examples, sensor body912may be comprised of most any material such as is common in printed circuit board design (e.g., FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy)). In another example, sensor body912may have a flexible design so it may contour to the cylindrical shape of elongated body12, thus ultrasonic sensors930and/or934as close to elongated body12as possible to ensure reliable ultrasonic sound transfer and sensor measurements. Flexible PCB materials include PI (polyimide) film and PET (polyester) film apart from which polymer film is also available like PEN (polyethylene nphthalate), PTFE and Aramid etc. Sensor body912may be removably coupled to elongated body such that sensor body912along with first and second sensor930,934may be removed from elongated body12and be reused in another catheter for another procedure or application. In other examples, sensor body912may be left on elongated body and disposed of after use.

Sensor901may require calibration information to be accurate. Sensor901may require sensor-specific calibration information to produce an accurate measurement and compensate for variability in sensor901. Sensor901may have memory919on sensor901that stores sensor calibration information that is used by external device24to more accurately read sensor data being sent from sensor901. In another example, memory19may store sensor calibration information to calibrate sensor901based on the sensor calibration information stored by memory19.

Ultrasonic flow sensor901may be a non-intrusive (e.g., clamp-on) transmission (e.g., a contra-propagating transit-time) flow meter. While the attachment mechanism for ultrasonic flow sensor901is not shown inFIG. 9A, elongated body12is shown with a bend960in elongated body12that generally corresponds to the “U” shape of sensor body912. Bend960may be created by a clamping or coupling mechanism to attach sensor body912to elongated body12in the configuration shown inFIG. 9A. Once medical device10is ready for disposal, sensor body912may be uncoupled or detached from elongated body12for use with another catheter. In other examples, ultrasonic sensors930and/or934may be attached separately by a user to elongated body12without a sensor body912attaching sensor930and934to each other and elongated body12. In other examples, ultrasonic sensors930and/or934may be integral with elongated body12and disposed of with elongated body12after the use of elongated body12. However, ultrasonic sensors may be expensive and cost prohibitive to use in a single-use medical device. Ultrasonic flow sensor901, therefore, may be reusable and coupled to sensor body912and not a permanent fixture on elongated body12. Sensor body912may be releasably connected, e.g., mechanically with latches, snaps, threads, slides, cams, deformable sensor body, elastic connections, or magnetically.

Ultrasonic sensors930and934are shown facing one another inFIGS. 9A and 9B(e.g., such that first and second sound waves932and936are transmitted in a path that is substantially parallel to the flow direction of fluid504and/or the longitudinal axis of elongated body12. However, ultrasonic sensors930and934may be positioned on elongated body12such that first and second sound waves932and936are transmitted in a path that that is at an angle to the flow direction of fluid504and/or the longitudinal axis of elongated body12Ultrasonic sensors930and934may also be tilted at an angle, from vertical, toward one another. In this manner, instead of facing each other where the ultrasonic signals travel directly between ultrasonic sensors930and934, each of the ultrasonic pulses may be transmitted, through fluid504in lumen34, bounce off of lumen34back through fluid504and be received by opposing ultrasonic sensors930and934. Thus, the ultrasonic signals would take a “V” shaped or non-linear route between ultrasonic sensors930and934. In other examples ultrasonic sensors930and934may be placed on elongated body12in most any fashion as long as ultrasonic sensor930may receive the ultrasonic transmission of ultrasonic sensor934and ultrasonic sensor934may receive the ultrasonic transmission of ultrasonic sensor930and a distance between ultrasonic sensors930and934may be known or determined (as will be discussed in detail below).

As described above, to determine a flow parameter of fluid504within lumen34(e.g., the average velocity and/or flow rate of fluid504) first ultrasonic sensor930transmits a first ultrasonic signal932in a first direction through a fluid504flowing distally within lumen34. Second ultrasonic sensor934may transmit a second ultrasonic signal936in a second direction through fluid504flowing distally within lumen34. Second ultrasonic sensor934may be positioned on elongated body12proximal to first ultrasonic sensor930. First ultrasonic sensor930may receive second ultrasonic signal936transmitted through fluid504flowing in lumen34. Second ultrasonic sensor934may receive first ultrasonic signal932transmitted through fluid504flowing in lumen34.

When first and second ultrasonic sensors930and934receive ultrasonic signals936and932respectfully, processing circuitry200, may determine a first transit time of first ultrasonic signal932where the first transit time is a time from transmission from first ultrasonic sensor930to reception by second ultrasonic sensor934. Processing circuitry200may determine a second transit time of second ultrasonic signal936where the second transit time is a time from transmission from second ultrasonic sensor934to reception by first ultrasonic sensor930. Processing circuitry200may determine an average flow velocity of fluid504through lumen34based on the determined first and second transit times of first932and second ultrasonic signals936. Processing circuitry200may also determine a flow rate of fluid504through lumen34based on the determined average flow velocity and a cross-sectional area of lumen34.

Processing circuitry200may use the transit times of ultrasonic sounds932and936, distance940and the inclination angle (which may be approximately zero degrees as first930and second ultrasonic sensor934are facing each other) with the following equation to find average velocity:

From the average velocity, processing circuitry may determine a volumetric flow rate. Flow rate may be calculated:

Processing circuitry200may determine other properties of fluid504utilizing known and determined attributes of fluid504. For example, the acoustic properties of fluid504may affect ultrasonic flow sensing within lumen34. Temperature, density, viscosity and suspended particulates in fluid504may impact ultrasonic flow sensing. Thus, memory919, memory19or memory202may have the constitutions of many possible fluids stored on memory919, memory19or memory202. Processing circuitry200may then determine specific information regarding fluid504using flow rate, average flow velocity to calculate or look up density, specific gravity, temperature, and/or the like.

Ultrasonic sensors930and934are shown inFIGS. 9A and 9Bfacing one another and substantially parallel to the flow in lumen34. Other examples may rely on the sound reflecting off portions of lumen34so ultrasonic sensors930and934do not necessarily have to be on opposite sides of lumen34. In other examples, ultrasonic sensors930and934may be positioned at an angle to the direction of flow. In this example, equation (1) above could be modified to multiply the denominator by the cosign of the inclination angle from the direction of lumen34. In another example, processing circuitry200may also detect frequency shifts through a doppler effect in first ultrasonic signal932. Processing circuitry200may determine a change in average flow velocity based on the frequency shifts by dividing a doppler frequency by the frequency of first ultrasonic signal932and multiplying the speed of sound. Processing circuitry200may determine a change in flow rate of fluid504through lumen34based on the average flow velocity and cross-sectional area of lumen34over time.

FIG. 10is a flow diagram illustrating an example technique for monitoring or otherwise sensing flow rate of fluid within a lumen using sensor901ofFIG. 9Aaccording to techniques of this disclosure. For ease of description, the example technique ofFIG. 10is describe an being carried out under the control of processing circuitry200. However, the example technique may be carried out any suitable processing circuitry either of medical device10or external device24, for example.

Processing circuitry200may begin a flow rate determining process in response to a user instructing ultrasonic sensor901to begin sensing fluid flow, e.g., as inputted via external device24. As stated above, ultrasonic sensor901may be powered by external device24routing power through connection38and/or by other suitable power source. A user may wait to initiate a flow rate sensing process until fluid504is flowing through lumen34. Ultrasonic sensor901may provide a power source onboard sensor body912and be powered on separately by a power switch on sensor body912in another example. Once powered on, a user can begin a flow rate sensing process. Results may be displayed on user interface204including any alarms caused by resultant data being out of any threshold values. For example, if the transit times between ultrasonic sensors930and934were substantially the same, this may indicate there is little to no fluid flow, which may indicate a blockage of lumen34.

Processing circuitry200may control first ultrasonic sensor930to transmit a first ultrasonic signal932in a first direction through fluid504flowing distally within lumen34defined by elongated body12(1002). Processing circuitry200may control second ultrasonic sensor934to transmit second ultrasonic signal936in a second direction through fluid504flowing distally within lumen34(1004). First ultrasonic signal932and second ultrasonic signal936may be transmitted simultaneously, substantially simultaneously or sequentially with each other.

As discussed above, first and second ultrasound sensor930and934may transmit sound waves932and936with ultrasonic frequencies. Ultrasound may refer to a sound wave with a frequency greater than the upper limit of human hearing, which is generally over 20 kHz. Among audible sounds not higher than 20 kHz, those not intended to be heard by humans may also be ultrasound. Ultrasound may travel through various media including gases, liquids and solids. Thus, ultrasonic signals932and936may travel efficiently through both elongated body12and fluid504. However, as noted above, ultrasonic signals932and936will travel differently through both. Thus, processing circuitry may have a calibration factor for the time traveled in elongated body12if ultrasonic sensors930and934are located outside of elongated body12.

Second ultrasonic sensor934may be positioned on elongated body12proximal to first ultrasonic sensor930. First ultrasonic sensor930may receive second ultrasonic signal936transmitted through fluid504flowing in lumen34(1006). Second ultrasonic sensor934may receive first ultrasonic sound932transmitted through fluid504flowing in lumen34(1008).

Processing circuitry200may determine a first transit time of first ultrasonic signal932where the first transit time is a time from transmission from first ultrasonic sensor930to reception by second ultrasonic sensor934(1010). A second transit time of second ultrasonic signal936may be calculated by the processing circuitry200, where the second transit time is a time from transmission from second ultrasonic sensor934to reception by first ultrasonic sensor930(1012).

An average transit time of ultrasonic signals932and936may be determined by processing circuitry200, based on the determined first and second transit times of first932and the second ultrasonic signals936(1014).

A velocity of fluid504through lumen34may be determined by processing circuitry200based on the determined average transit time (1016). Processing circuitry200may determine a flow rate based on the flow velocity (1018).

In addition to, or as an alternative to, determining velocity and/or flow rate of fluid504based on the average transit time of first and second sound waves932and936through fluid504, processing circuitry may determine the velocity and/or flow rate based on frequency shifts. For example, processing circuitry200may also detect frequency shifts through a doppler effect in first ultrasonic signal932. Processing circuitry may determine a change in flow velocity based on the frequency shifts by dividing a doppler frequency by the frequency of first ultrasonic signal932and multiplying a speed of sound. Processing circuitry may determine a change in flow rate of fluid504through lumen34based on the flow velocity and a cross-sectional area of lumen34over time. Doppler shift may use the reflection of an ultrasonic signal off sonically reflective materials, such as solid particles or entrained air bubbles in flowing fluid504, or the turbulence of fluid504.

In another example, sensor901may be used to perform the above techniques on multiple different catheters by being removable from elongated body12and subsequently couple to another elongated body, e.g., in the manner described herein and shown inFIG. 9B.

While oxygen sensor701and ultrasonic flow sensor901are described above as being separate sensors, in some examples, sensor20on elongated body12inFIG. 1may be a combination of each of oxygen sensor701and ultrasonic flow sensor901.FIGS. 13A and 13Bare diagrams illustration an example combination ultrasonic flow sensor and oxygen sensor for an elongated body according to techniques of this disclosure. Oxygen sensor701and ultrasonic flow sensor901may be combined on one sensor body1312. Fluorescence material702may still be located within lumen34. Sensor body1312may house first930and second ultrasonic sensor934, light source704and light detector710. Optional lens714may be coupled to disposable elongated body12or lens714may be part of reusable sensor body1312. Sensor body1312may be coupled to elongated body12using any suitable coupling mechanisms or techniques. The coupling mechanism (not shown inFIG. 13A) used may create bend960that may allow for ultrasonic sensors930and934to substantially face one another. As described above with regard to sensors701and901, in some examples, all or a portion of sensor body1312may be removably coupled from elongated body12.FIG. 13Bshows sensor body1312separated from elongated body12, where elongated body include fluorescence material702and optional lens714. In this manner, sensor body1312may be removed from elongated body12, e.g., after elongated body12is no longer in use in a patient, so that sensor body1312may be coupled to another elongated body to provide the sensing functions described herein for sensors701and901.

FIG. 11is a flow diagram illustrating an example technique for determining a density and/or temperature of a fluid within a lumen of a catheter, such as drainage lumen34of medical device10, in accordance with some examples of the disclosure. In some examples, sensor20of medical device10may be configured to sense a flow parameter of a fluid within lumen34of elongated body12, and processing circuitry200and/or other processing circuitry may determine at least one of a density parameter or a temperature parameter of the fluid within lumen34based on the sensed flow parameter. For ease of description, the example ofFIG. 11is described primarily with regard to medical device10ofFIG. 1but it is understood that any catheter with a suitable sensor may be employed.

As shown inFIG. 11, sensor20located on elongated body12defining lumen34may sense a flow parameter of fluid504within lumen34of medical device10(1102). In one example, sensor20may be an ultrasonic sensor such as sensor901. As described above, sensor901may be configured to determine the transit times of first and second sound waves932and936through fluid504. Sensor901may measure the flow of fluid504through lumen34by measuring the difference in transit times of the sound waves traveling against the flow of fluid504and the transit time of the sound waves traveling with the flow of fluid504. The difference in the transit times in conjunction with the channel dimensions and fluid characteristics can be used to calculate the flow rate of the fluid.

In addition to, or as an alternative to, using the transit time difference to calculate the flow rate, processor200may use the average transit time of the upstream and downstream direction, e.g., to calculate characteristics of fluid504such as temperature and/or density. For example, both temperature and density affect the speed of sound in a fluid. By measuring the average transit time in a known geometry (e.g., the geometry of lumen34), the changes in density and temperature of fluid504may be calculated by processor200.

As shown inFIG. 11, processing circuitry200may determine a density parameter (density/specific gravity value and/or change in density/specific gravity over a period of time) and/or temperature parameter (e.g., a temperature value or a change in temperature) of fluid504based on the sensed flow parameter (1104). For example, processing circuitry200may execute software208, another algorithm stored on memory919, memory19or memory202or reference a lookup table stored on memory919, memory19or memory202to determine a density parameter or a temperature parameter of fluid504in lumen34based on the sensed flow parameter of fluid504(1104). Density and temperature both affect the speed of sound in fluid504. If the distance between first930and second ultrasonic sensor934and time are known, the average velocity may be calculated. If the average velocity is known, temperature may be determined. A level of dissolved solids in fluid504may change the density and changes of density also change the speed of sound in fluid504. If the average velocity and temperature are both known, the density may be calculated. There may be several lookup tables stored on memory919, memory19or memory202where the lookup table may be based on the type of fluid within lumen34.

In another example of the present disclosure, sensor901may be configured to sense at least one flow parameter of fluid504within lumen34of elongated body12to allow for medical device10or other device to determine (e.g., via processing circuitry200) at least one of a density parameter or a temperature parameter of the fluid in lumen34based on the sensed flow parameter of the fluid. For example, sensor901where the flow is calculated by measuring the difference in the transit time of sound traveling against the fluid flow and the transit time of sound traveling with the fluid flow. The difference in the transit times in conjunction with dimensions of lumen34and the constitution of the fluid may be used to calculate the volumetric flow rate of the fluid. In addition, the average transit time of the upstream and downstream sound can be used to calculate characteristics of the fluid; such as temperature and density. By measuring the average transit time in a known geometry (e.g., lumen34), changes in density and temperature may be calculated. For example, the temperature may be measured by a different means (e.g., a thermal dilution flow sensor500) and this temperature in combination with the other known variables, such as lumen geometry and volumetric flow rate, may be used to calculate the density of the fluid by processing circuitry200. In another example, processing circuitry200may determine the density of the urine using the average transit time when flow is high and the fluid is assumed to be at body temperature (e.g., 98.6° F.). In another example, body temperature may be measured using a temperature sensor at proximal end12B, from other body temperature measuring devices, or assumed to be normal. The density of fluids, usually represented as the specific gravity, may be an important and common measurement (e.g. urinalysis). For example, the specific gravity of urine can be used to understand a patients' hydration status and the filtration capabilities of patient. The ability to measure urine density continuously and quickly can aid in understanding of the state of patient.

Further, processing circuitry200, may not only make a determination of density at a specific time, but may also determine a density value for an average over a time period and/or measuring continuously or periodically to identify increases or decreases in density of a period of time even if density is not determined at a particular time period.

In another example, memory919, memory19and/or memory202may have a lookup table providing a density and/or temperature for fluid504based upon detected average transit time changes and the constitution of fluid504. The detected transit time changes may indicate a change in the speed of sound through fluid504indicating a possible change in density. Processing circuitry200may use an algorithm or a lookup table within memory919, memory19or member202that correlates the change in transit time to a change in density and or a change in temperature.

Since temperature and density are inversely proportional, once a density is known a temperature may be determined, e.g., through an algorithm or a lookup table which correlates density to temperature for a specific fluid. If either of density or temperature are determined to be out of a threshold value, then an alarm may be sounded or given visually at user interface204. During operation, density and temperature may be displayed on user interface204or external device121for a clinician to monitor

In one example, the temperature of fluid504may be determined by processing circuitry200with known values (e.g., by one or more of the temperature sensors of sensor500) and the temperature and ultrasound transit times may be used to calculate the density of fluid504. In another example, the density of the fluid504may be measured using the average transit times determine by sensor901, e.g., when flow is relatively high and fluid504is assumed to be at body temperature. In some examples, the body temperature of a patient may be measured using medical device10with a sensor at proximal end12B, e.g., from other body temperature measuring devices, or assumed to be a normal temperature of urine or body temperature.

In an example of the present disclosure, the flow parameter sensed by sensor20may be an average transit time of fluid504through at least a portion of lumen34, e.g., as describe above with regard to ultrasonic sensor901. In another example, the flow parameter may be a temperature difference from thermal dilution sensor500.

In some examples, the determined density parameter may be at least one of a density of fluid504, a specific gravity of fluid504, a change in the density of fluid504over time, or a change in the specific gravity of fluid504. In some examples, the determined temperature parameter may be at least one of a temperature of fluid504or a change in the temperature of fluid504over time. Again, as described above, both temperature and density influence the speed of sound (e.g., sound waves) in a fluid. By measuring the average transit time, e.g. in the manner described herein with ultrasonic sensor901, in a known geometry, the changes in density and temperature may be calculated.

The density of urine, usually represented as the specific gravity, is a measurement used in urinalysis. The specific gravity of urine may be used to understand a patients' hydration status and the filtration capabilities of a patient. The ability to measure urine density, e.g., substantially continuously and/or quickly, may aid in understanding of the state of patient. As such, using the technique ofFIG. 11to determine the density/specific gravity of fluid504within lumen34, the system ofFIG. 1may aid a user in understanding the state of the patient, particularly with regard to hydration status and/or filtration capabilities of the patient in which medical device10is inserted as a urinary catheter.

In another example, processing circuitry200may determine a hydration status of a patient. Once processing circuitry200has determined a density, a specific gravity may be determined as well as specific gravity is the density of a substance divided by the density of water. If fluid504is too concentrated this may mean a patient's kidneys aren't functioning properly or they are dehydrated. This may initiate an alarm on user interface204, either visual or auditory. If fluid504isn't concentrated enough it may mean a patient may have a rare condition called diabetes insipidus, which causes thirst and the excretion of large amounts of diluted urine. Knowing urine specific gravity is a quick way a clinician to tell if the patient's kidneys are trying to compensate for some abnormality. Specific gravity may be helpful in indicating any of dehydration or overhydration, heart failure, shock, diabetes, insipidus, kidney failure, kidney infection, urinary tract infection, hyponatremia, or low sodium levels, hypernatremia, or elevated sodium levels

FIG. 12is a flow diagram illustrating an example technique for calibrating one or more sensors of a catheter, such as, medical device10, according to techniques of this disclosure. The technique ofFIG. 12may be employed to calibrate one or more sensors employed by a catheter such as sensors20,500,701, and/or901. In some examples, the technique ofFIG. 12may be used in cases in which medical device10includes both an elongated body12that is configured to be disposed after use, while sensors20,500,701, and/or901may be detachably coupled to elongated body12so that sensor20,500,701, and/or901may be reused and/or may allow for one or more of a variety of different sensors to be coupled to elongated body12after manufacture of elongated body12. As described below, elongated body12may include a memory19that stores calibration information that is specific to elongated body12. Each sensor20,500,701, and/or901that may be coupled to elongated body12, may have a memory519,719and919that stores calibration information specific to sensor500,701, and/or901respectively for calibration used for the sensing functionality. While examples are described with regard to sensor20,500,701, and/or901, such a technique may be employed for any sensor that is coupled to elongated body12of medical device10.

As shown inFIG. 12, one or more of sensors20,500,701or901may be releasably coupled to elongated body12(1202). The coupling may occur in most any manner such as temporary adhesives, clamping, clipping, pad mounting, magnetic mounting etc. One or more of each sensor may have a memory519,719and/or919.

Memories519,719, and/or9191may store sensor calibration information that is useful to one or more of sensors20,500,701or901. Sensors20,500,701or901may be calibrated based on the sensor calibration information stored by memories519,719, and/or919(1204). One of sensors20,500,701or901may be configured to sense one or more parameters of a fluid504within lumen34of elongated body12and adjust the sensed one or more parameters based on the stored calibration information (1206).

Calibration information may be required for a new instrument. For example, if sensor20,500,701, or901are swapped out with a different sensor or replaced with a similar sensor, processing circuitry200may need obtain calibration information from the new sensor. This calibration information may be stored on a memory on the new sensor that may also be necessary for replacement pieces or parts of sensor20,500,701, or901. For example, replacement of a temperature sensor502on sensor500. Calibration may also be necessary after an instrument has been repaired or modified.

Each of sensor20,500,701, or901may need calibration after a specified time period has elapsed. For example, after sensor20has been used for 100 hours it may be necessary to calibrate sensor20to ensure sensor20is still operating properly. In some instances, an operator may desire each sensor to be calibrated before each procedure to ensure proper readings during procedures. Processing circuitry200may monitor readings provided by sensors20,500,701and901and whenever observations appear questionable or instrument indications do not match the output of surrogate instruments a calibration may be performed.

A sensor such as sensor20,500,701, and/or901may require calibration information to be accurate. As described above, a flow sensor500and/or901and an oxygen sensor701may be incorporated into medical device10and, in some examples, may be removably coupled to elongated body12. One or more of these sensors may require sensor-specific calibration information to produce relatively accurate measurement to compensate for variability in the sensors. For example, thermal dilution flow sensor500may require information that correlates actual flow to a measured temperature difference. Variability in the temperature differences occurs due to small differences in heater member512, temperature sensors502and/or508, the lumen dimensions, or the position of the heater member512or temperature sensors502and/or508. Calibration information on memory519could provide known calibration standards for each of heater member512, temperature sensors502and508, dimensions of a known elongated body12. This information can be used to correct for manufacturing variations in temperature sensors502and508, heater member512, lumen34, and other geometries, as well as used in algorithms or lookup tables to provide information such as geometry of lumen34or flow calculations dependent on the location of temperature sensor508and its distance from heating member512. In an example, the calibration information may provide coefficients for an algorithm that fit flow data to temperature changes for a specific sensor for a specific type of fluid.

By including the sensor calibration in or on the sensor, the accuracy of the measurements as well as the flexibility to change the components in the sensor or offer different ranges of sensors in the future, is possible without changing the software in the monitoring.

The sensor calibration information may be specific calibration information for manufacturing variations within sensor20,500,701or901.

In one example where the calibration information may be specific to sensor500, the calibration information may include, manufacturing variations in sensor500, dimensions of lumen34(e.g., for area, volume, density and temperature calculations), a position of heating member512on elongated body12, a position of first temperature sensor502on elongated body12, a position of second temperature sensor508on elongated body12, a type of heating member512, a type of first temperature sensor502, a type of second temperature sensor508or a constitution of the fluid504within lumen34.

The calibration information on memory519may be used in the process of adjusting the output or indication on sensors502and/or508to agree with value of the applied standard, within a specified accuracy. For example, thermometer502or508may be calibrated so the error of indication or the correction is determined and adjusted (e.g. via calibration constants) so that it shows the true temperature at specific points. This is the display at user interface204.

In another example, where the calibration information may be specific to ultrasonic flow sensor901and may include, manufacturing variations in sensor901(e.g., small variations in the frequency of first930and/or second ultrasonic sensor934and any geometric variability to the sensor assembly), dimensions of lumen34(e.g., for area, volume, density and temperature calculations), a position of first ultrasonic sensor930on elongated body12, a position of second ultrasonic sensor934on elongated body12(e.g., distance940between first930and second ultrasonic sensor934), a type of first ultrasonic sensor630, a type of second ultrasonic sensor634or a constitution of the fluid504in lumen34(e.g., urine, blood, etc.).

The calibration information located on memory919may be used by processing circuitry200that, under specified conditions, establishes a relation between the quantity values measured by sensors20,500,701, or901with measurement uncertainties provided by measurement standards stored on memory919. Processing circuitry200may use this information to establish a relation for obtaining a measurement result. Processing circuitry200may perform a calibration process or a comparison to reduce or eliminate measurement uncertainty in relating the accuracies of sensors20,500,701, and901.

In another example, where the calibration information may be specific to oxygen sensor701, the calibration information may include: dimensions of lumen34, fluorescing properties of fluoresce material702(e.g., different fluoresce materials may react differently to different fluids), a type of light source704(e.g., one light source may be brighter than another or emit a different wavelength of light) or a type of light receptor610. For example, light source704may have variations in intensity, wavelength (e.g., a manufacturing variation), etc. There may also exist minor assembly variations in materials and alignments that may affect the accuracy of the measurements. As discussed above, processing circuitry200may compare a known fluorescence rate with a detected fluorescence rate of fluoresce material702. If the detected fluorescence is off by a certain amount, processing circuitry200may apply a calibration factor to account for the offset. This process may be extended to light706emitted by light source704. For example, if light706is replaced, processing circuitry may use calibration information stored on memory719to account for any difference and then take this difference into account with measurements coming from light detector710.

Many sensors provide more accurate readings when calibrated or provided with calibration information to ensure accurate readings. Sensors20,500,701and901may use sensor-specific calibration information to compensate for variability in sensors20,500,701and901and produce a more accurate measurement.

For example, flow sensor500may use information that correlates actual flow to measured temperature difference. Variability in the temperature differences occur due to small differences in heater member512, temperature sensors502and508, the lumen dimensions, or the position of heater element512or temperature sensors502and508.

Similarly, oxygen sensor701may have specific calibration parameters related to fluorescing material702used, as well as the specifics of light source704and light detector710.

Sensor calibration data onboard memories519,719or919may calibrate measurements as well as allow the flexibility to change the components in sensors20,500,701and901or offer different ranges of sensors20,500,701and901in the future without changing software208.

Various examples have been described. These and other examples are within the scope of the following claims. For purposes of this disclosure, the operations shownFIGS. 6, 8, 10, 11 and 12do not need to be executed in the manner suggested by the illustrations and, unless specifically stated so, may be executed in any order. Further, the term substantially is to be given its standard definition of to a great or significant extent or for the most part; essentially.

The following is a non-limiting list of examples that are in accordance with one or more techniques of this disclosure.

Example 1A. A device comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a first temperature sensor configured to sense a first temperature of a fluid at a first location in the lumen; a second temperature sensor configured to sense a second temperature of the fluid at a second location in the lumen, the first location being proximal to the second location; and a heating member located proximal to the second temperature sensor, the heating member configured to heat the fluid within the lumen.

Example 2A. The device of example 1A, further comprising processing circuitry configured to determine a flow of the fluid within the lumen based on a difference between the first temperature and the second temperature.

Example 3A. The device of any one of examples 1A-2A, wherein the heating member is located between the first temperature sensor and the second temperature sensor.

Example 4A. The device of any one of examples 1A-2A, wherein the heating member is located proximal to the first temperature sensor and the second temperature sensor.

Example 5A. The device of any one of examples 1A-4A, wherein the first temperature sensor, the second temperature sensor, and the heating member are configured to be releasably coupled to the elongated body.

Example 6A. The device of any of examples 1A-5A, wherein a diameter of the lumen is a smaller diameter to decrease a flow of the fluid.

Example 7A. The device of any of examples 1A-6A, wherein the first temperature sensor and the second temperature sensors each comprise at least one of a thermocouple sensor or a thermistor sensor.

Example 8A. The device of any of examples 1A-7A, further comprising an oxygen sensor configured to sense oxygen concentration in the fluid within the lumen, wherein the oxygen sensor is configured to be calibrated based on at least one of the first sensed temperature or the second sensed temperature.

Example 9A. The device of example 8A, wherein the oxygen sensor comprises: a fluoresce material, located within the lumen, configured to contact and react with the fluid in the lumen; a light source configured to emit a specific wavelength of light, the fluoresce material within the fluid being fluorescent when exposed to the wavelength of light and oxygen in the fluid, where the greater the amount of oxygen in the fluid the lower an intensity in fluoresce in the fluid; and a light detector configured to detect the emitted fluorescence.

Example 10A. The device of example 9A, wherein the amount of fluorescence given off by the fluoresce material is temperature dependent.

Example 11A. The device of any of examples 8A-10A, wherein the oxygen sensor is located proximal to the heating member, and the oxygen sensor is calibrated based on the first sensed temperature.

Example 12A. The device of any of examples 1A-11A, wherein the elongated body comprises a Foley catheter.

Example 1B. A method comprising: heating, with a heating member a fluid within a lumen defined by an elongated body comprising a proximal portion and a distal portion; sensing, with a first temperature sensor, a first temperature of a fluid at a first location in the lumen; and sensing, with a second temperature sensor, a second temperature of the fluid at a second location in the lumen, the first location being proximal to the second location.

Example 2B. The method of example 1B, further comprising determining, with processing circuitry, a flow of the fluid within the lumen based on a difference between the first temperature and the second temperature.

Example 3B. The method of any of examples 1B-2B, wherein the heating member is located between the first temperature sensor and the second temperature sensor.

Example 4B. The method of any of examples 1B-2B, wherein the heating member is located proximal to the first temperature sensor and the second temperature sensor.

Example 5B. The method of any of examples 1B-4B, further comprising releasably coupling the first temperature sensor, the second temperature sensor, and the heating member to the elongated body.

Example 6B. The method of any of examples 1B-5B, wherein a diameter of the lumen is a smaller diameter to decrease a flow of the fluid.

Example 7B. The method of any of examples 1B-6B, wherein the first temperature sensor and the second temperature sensors each comprise at least one of a thermocouple sensor or a thermistor sensor.

Example 8B. The method of any of examples 1B-7B, further comprising: sensing, with an oxygen sensor, oxygen concentration in the fluid within the lumen; and calibrating the oxygen sensor based on at least one of the first sensed temperature or the second sensed temperature.

Example 9B. The method of example 8B, further comprising: controlling a light source to emit light to expose a fluorescence material to the emitted light, wherein the fluorescence material within a fluid is configured to fluoresce when exposed to the light in the lumen defined by an elongated body comprising a proximal portion and a distal portion; detecting, with a light detector, the fluorescence of the fluorescence material; and detecting, based on the detected fluorescence, oxygen in the fluid within the lumen.

Example 10B. The method of example 9B, wherein the amount of fluorescence given off by the fluoresce material is temperature dependent.

Example 11B. The method of any of examples 8B-10B, wherein the oxygen sensor is located proximal to the heating member, and the oxygen sensor is calibrated based on the first sensed temperature.

Example 12B. The method of any of examples 8B-11B, wherein the oxygen sensor is located distal to the device, and the oxygen sensor is calibrated based on the second sensed temperature.

Example 1C. A device comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a first temperature sensor configured to sense a first temperature of a fluid at a first location in the lumen; a second temperature sensor configured to sense a second temperature of the fluid at a second location in the lumen, the first location being proximal to the second location; a heating member located proximal to the second temperature sensor, the heating member configured to heat the fluid within the lumen; processing circuitry configured to determine a flow of the fluid within the lumen based on a difference between the first temperature and the second temperature; and an oxygen sensor configured to sense oxygen concentration in the fluid within the lumen, wherein the oxygen sensor is configured to be calibrated based on at least one of the first sensed temperature or the second sensed temperature.

Example 1D. A medical device system comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; a sensor coupled to the elongated body, the sensor comprising: a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen; and a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor; wherein the first ultrasonic sensor is configured to receive the second ultrasonic signal transmitted through the fluid flowing in the lumen; wherein the second ultrasonic sensor is configured to receive the first ultrasonic sound transmitted through the fluid flowing in the lumen.

Example 2D. The system of example 1D, further comprising processing circuitry configured to: determine a first transit time of the first ultrasonic signal, the first transit time is a time from transmission from the first ultrasonic sensor to reception by the second ultrasonic sensor; and determine a second transit time of the second ultrasonic signal, the second transit time is a time from transmission from the second ultrasonic sensor to reception by the first ultrasonic sensor; and determine a flow velocity of the fluid through the lumen based on the determined first and second transit times of the first and the second ultrasonic signals.

Example 3D. The system of example 2D, wherein the processing circuitry is configured to determine a flow rate of the fluid through the lumen based on the determined flow velocity and a cross-sectional area of the lumen.

Example 4D. The system of example 2D, wherein the processing circuitry is configured to determine an average velocity by dividing a distance between the first and the second ultrasonic sensors with the first and second transit times and.

Example 5D. The system of example 4D, wherein the average velocity is determined by multiplying half the distance between the first and second sensors by the difference of the transit time of the first ultrasonic signal and the second ultrasonic signal divided by the multiplication of the transit time of the first ultrasonic signal and the second ultrasonic signal.

Example 6D. The system of examples 2D, wherein the processing circuitry is configured to detect frequency shifts through a doppler effect in the first ultrasonic signal.

Example 7D. The system of example 6D, wherein the processing circuitry is configured to determine a change in flow velocity based on the frequency shifts by dividing a doppler frequency by the frequency of the first ultrasonic signal and multiplying a speed of sound.

Example 8D. The system of any of examples 6D-7D, wherein the processing circuitry is configured to determine a change in flow rate of the fluid through the lumen based on the flow velocity and a cross-sectional area of the lumen over time.

Example 9D. The system of any of examples 1D-8D, wherein the sensor coupled to the elongated body is configured to be removed from the elongated body.

Example 10D. The system of any of examples 1D-9D, wherein the sensor is configured to be reused.

Example 11D. The system of any of examples 1D-10D, wherein the sensor further comprises an oxygen sensor.

Example 12D. The system of example 11D, wherein the oxygen sensor comprises: a fluoresce material, located within the lumen, configured to contact and react with the fluid in the lumen; a light source configured to emit a specific wavelength of light, the fluoresce material within the fluid being fluorescent when exposed to the wavelength of light and oxygen in the fluid, where the greater the amount of oxygen in the fluid the lower an intensity in fluoresce in the fluid; and a light detector configured to detect the emitted fluorescence.

Example 13D. The system of any of examples 1D-12D, wherein the first ultrasonic sensor at least partially faces the second ultrasonic sensor.

Example 14D. The system of any of examples 1D-13D, wherein the first ultrasonic sensor transmits the first ultrasonic signal, at least partially, with a flow direction of the fluid and the second ultrasonic sensor transmits the second ultrasonic signal, at least partially, against the flow direction of the fluid.

Example 15D. The system of examples 1D-13D, wherein the first ultrasonic sensor or the second ultrasonic sensor is substantially parallel to the fluid flow in the lumen.

Example 16D. The system of any of examples 1D-12D, wherein the first ultrasonic sensor and the second ultrasonic sensor are pointed at an angle to the fluid flow and the first and the second ultrasonic signal are reflected off of a lumen wall before they are received.

Example 17D. The system of any of examples 1D-16D, wherein the elongated body comprises a Foley catheter.

Example 1E. A method comprising: transmitting, with a first ultrasonic sensor, a first ultrasonic signal in a first direction through a fluid flowing distally within a lumen defined by an elongated body comprising a proximal portion and a distal portion; transmitting, with a second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor, a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen; receiving, with the first ultrasonic sensor, the second ultrasonic signal transmitted through the fluid flowing in the lumen; and receiving, with the second ultrasonic sensor, the first ultrasonic sound transmitted through the fluid flowing in the lumen.

Example 2E. The method of example 1E, further comprising: determining, with processing circuitry, a first transit time of the first ultrasonic signal, wherein the first transit time is a time from transmission from the first ultrasonic sensor to reception by the second ultrasonic sensor; and determining, with the processing circuitry, a second transit time of the second ultrasonic signal, wherein the second transit time is a time from transmission from the second ultrasonic sensor to reception by the first ultrasonic sensor; and determining, with the processing circuitry, a flow velocity of the fluid through the lumen based on the determined first and second transit times of the first and the second ultrasonic signals.

Example 3E. The method of example 2E, further comprising determining, with the processing circuitry, a flow rate of the fluid through the lumen based on the determined flow velocity and a cross-sectional area of the lumen.

Example 4E. The method of example 2E, further comprising determining, with the processing circuitry, an average velocity by dividing a distance between the first and the second ultrasonic sensors with the first and second transit times.

Example 5E. The method of example 4E, wherein the average velocity is determined by half the distance between the first and second sensors, multiplied by, the difference of the transit time of the first ultrasonic signal and the second ultrasonic signal, divided by, the transit time of the first ultrasonic signal multiplied by the transit time of the second ultrasonic signal.

Example 6E. The method of example 2E, further comprising detecting, with the processing circuitry, frequency shifts through a doppler effect in the first or the second ultrasonic signal.

Example 7E. The method of example 6E, further comprising determining, with the processing circuitry, a change in flow velocity based on the frequency shifts by dividing a doppler frequency by the frequency of the first ultrasonic signal and multiplying a speed of sound.

Example 8E. The method of any of examples 2E-3E, further comprising determining, with the processing circuitry, a change in flow rate of the fluid through the lumen based on the flow velocity and a cross-sectional area of the lumen over time.

Example 9E. The method of any of examples 1E-8E, wherein the first ultrasonic sensor and the second ultrasonic sensor are coupled to a sensor body configured to be removably attached to the elongated body.

Example 10E. The method of any of examples 1E-9E, wherein the sensor body is configured to be reusable.

Example 11E. The method of any of examples 1E-10E, wherein the sensor body further comprises an oxygen sensor.

Example 12E. The method of example 11E, further comprising: controlling a light source to emit light to expose a fluorescence material to the emitted light, wherein the fluorescence material within a fluid is configured to fluoresce when exposed to the light in the lumen defined by an elongated body comprising a proximal portion and a distal portion; detecting, with a light detector, the fluorescence of the fluorescence material; and detecting, based on the detected fluorescence, oxygen in the fluid within the lumen.

Example 13E. The method of any of examples 1E-12E, wherein the first ultrasonic sensor at least partially faces the second ultrasonic sensor.

Example 14E. The method of example 13E, wherein the first ultrasonic sensor transmits the first ultrasonic signal, at least partially, with a flow direction of the fluid and the second ultrasonic sensor transmits the second ultrasonic signal, at least partially, against the flow direction of the fluid.

Example 15E. The method of example 13E, wherein the first ultrasonic sensor or the second ultrasonic sensor is substantially parallel to the fluid flow in the lumen.

Example 16E. The method of 1E, wherein the first ultrasonic sensor and the second ultrasonic sensor are pointed at an angle to the fluid flow and the first and the second ultrasonic signal are reflected off of a lumen wall before they are received.

Example 17E. The method of any of examples 1E, 13E, 14E and 16E, wherein the first ultrasonic sensor is located on an opposite side of the elongated body from the second ultrasonic sensor.

Example 1F. A medical device system comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; a sensor coupled to the elongated body, the sensor comprising: a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen; a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor; and processing circuitry configured to: determine a first transit time of the first ultrasonic signal, the first transit time is a time from transmission from the first ultrasonic sensor to reception by the second ultrasonic sensor; determine a second transit time of the second ultrasonic signal, the second transit time is a time from transmission from the second ultrasonic sensor to reception by the first ultrasonic sensor; and determine a flow velocity of the fluid through the lumen based on the determined first and second transit times of the first and the second ultrasonic signals. wherein the first ultrasonic sensor is configured to receive the second ultrasonic signal transmitted through the fluid flowing in the lumen; wherein the second ultrasonic sensor is configured to receive the first ultrasonic sound transmitted through the fluid flowing in the lumen.

Example 1G. A system comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a fluorescence material configured to be located within the lumen with a fluid in the lumen; a light source configured to emit light to expose the fluorescence material to the emitted light, wherein the fluorescence material within the fluid is configured to fluoresce when exposed to the light in the lumen; and a light detector configured to detect the fluorescence of the fluorescence material, wherein the device is configured to detect oxygen in the fluid within the lumen based on the detected fluorescence.

Example 2G. The system of example 1G, wherein the light source and the light detector are both releasably coupled to the elongated body.

Example 3G. The system of any of examples 1G-2G, further comprising a sensor body configured to be releasably coupled to the elongated body, the sensor body supporting the light source and the light detector.

Example 4G. The system of any of examples 1G-3G, further comprising a lens configured to be placed on the elongated body in between the fluorescence material and light source.

Example 5G. The system of example 4G, wherein the lens is configured to focus the light to the fluorescence material in the lumen.

Example 6G. The system of any of examples 4G-5G, wherein the lens is configured to focus the fluorescence from the fluorescence material to the light detector.

Example 7G. The system of any of examples 1G-3G, further comprising a lens configured to be placed on the elongated body in between the fluorescence material and the light source.

Example 8G. The system of example 7G, wherein the lens is configured to be coupled to the reusable base portion.

Example 9G. The system of any of examples 3G-8G, further comprising: a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen; and a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor.

Example 10G. The system of example 9G, wherein the first and the second ultrasonic sensor are coupled to the reusable base portion.

Example 1H. A method comprising: controlling a light source to emit light to expose a fluorescence material to the emitted light, wherein the fluorescence material within a fluid is configured to fluoresce when exposed to the light in the lumen defined by an elongated body comprising a proximal portion and a distal portion; detecting, with a light detector, the fluorescence of the fluorescence material; and determining, based on the detected fluorescence, oxygen in the fluid within the lumen.

Example 2H. The method of example 1H, wherein the light source and the light detector are both releasably coupled to the elongated body.

Example 3H. The method of any of examples 1H-2H, wherein the light source and the light detector are coupled to a sensor body configured to be releasably coupled to the elongated body.

Example 4H. The method of any of examples 1H-3H, further comprising focusing the emitted light through a lens configured to be placed on the elongated body in between the fluorescence material and light source.

Example 5H. The method of example 4H, wherein the lens is configured to focus the light to the fluorescence material in the lumen.

Example 6H. The method of and of examples 4H-5H, further comprising focusing the fluorescence from the fluorescence material to the light detector.

Example 7H. The method of any of examples 4H-6H, wherein the lens is located on the elongated body in between the fluorescence material and the light source.

Example 8H. The method of example 7H, wherein the lens is configured to be coupled to the reusable base portion.

Example 9H. The method of any of examples 3H-8H, further comprising: transmitting, with a first ultrasonic sensor, a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen; and transmitting, with a second ultrasonic sensor, a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor.

Example 10H. The method of any of examples 1H-9H, wherein the elongated body comprises a Foley catheter.

Example 11. A system comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a fluorescence material configured to be located within the lumen with a fluid in the lumen; a light source configured to emit light to expose the fluorescence material to the emitted light, wherein the fluorescence material within the fluid is configured to fluoresce when exposed to the light in the lumen; a light detector configured to detect the fluorescence of the fluorescence material; a sensor body configured to be releasably coupled to the elongated body, the sensor body supporting the light source and the light detector; a lens configured to be placed on the elongated body in between the fluorescence material and light source; a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through a fluid flowing distally within the lumen; and a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor; wherein the device is configured to detect oxygen in the fluid within the lumen based on the detected fluorescence.

Example 1J. A system comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a sensor located on the elongated body, the sensor configured to sense at least one flow parameter of a fluid within the lumen; and processing circuitry configured to determine at least one of a density parameter or a temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid.

Example 2J. The system of example 1J, wherein the at least one flow parameter sensed by the sensor comprises an average transit time of the fluid through at least a portion of the lumen.

Example 3J. The system of any of examples 1J-2J, wherein the density parameter comprises at least one of a density of the fluid, a specific gravity of the fluid, a change in the density of the fluid, or a change in the specific gravity of the fluid.

Example 4J. The system of any of examples 1J-3J, wherein the temperature parameter comprises at least one of a temperature of the fluid or a change in the temperature of the fluid.

Example 5J. The system of any of examples 1J-4J, wherein the processing circuitry is configured to determine the at least one of the density parameter or the temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid and a geometry of the lumen.

Example 6J. The system of example 5J, wherein the geometry of the lumen includes a volume of at least a portion of the lumen.

Example 7J. The system of any of examples 1J-7J, further comprising a temperature sensor configured to determine a temperature of the fluid within the lumen, wherein the processing circuitry is configured to determine the density parameter of the fluid based on the at least one flow parameter and the determined temperature of the fluid.

Example 8J. The system of example 7J, wherein the temperature sensor is located on the elongated body.

Example 9J. The system of example 1J, wherein the processing circuitry is configured to determine the density parameter of the fluid based on the at least one flow parameter and an estimated temperature of the fluid.

Example 10J. The system of example 9J, wherein the estimated temperature of the fluid is estimated based on a sensed body temperature of a patient in which the elongated body is at least partially inserted.

Example 11J. The device of any of examples 1J-10J, wherein the processing circuitry is configured to: determine the density parameter of the patient based on the sensed at least one flow parameter of the fluid, and determine a hydration status of a patient based on the determined density parameter, the elongated body being at least partially inserted within the patient.

Example 12J. The device of any of example 1J-11J, wherein the sensor comprises: a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through the fluid flowing distally within the lumen; and a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor.

Example 13J. The system of any of examples 1J-12J, wherein the elongated body comprises a Foley catheter.

Example 1K. A method comprising: sensing, with a sensor located on an elongated body defining a lumen the elongated body comprising a proximal portion and a distal portion, at least one flow parameter of a fluid within the lumen; and determining, with processing circuitry, at least one of a density parameter or a temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid.

Example 2K. The method of example 1K, wherein the at least one flow parameter sensed by the sensor comprises an average transit time of the fluid through at least a portion of the lumen.

Example 3K. The method of any of examples 1K-2K, wherein the density parameter comprises at least one of a density of the fluid, a specific gravity of the fluid, a change in the density of the fluid, or a change in the specific gravity of the fluid.

Example 4K. The method of any of examples 1K-3K, wherein the temperature parameter comprises at least one of a temperature of the fluid or a change in the temperature of the fluid.

Example 5K. The method of any of examples 1K-4K, further comprising determining, with the processing circuitry, the at least one of the density parameter or the temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid and a geometry of the lumen.

Example 6K. The method of example 5K, wherein the geometry of the lumen includes a volume of at least a portion of the lumen.

Example 7K. The method of any of examples 1K-6K, further comprising determining, with a temperature sensor, a temperature of the fluid within the lumen, and determining, with the processing circuitry, the density parameter of the fluid based on the at least one flow parameter and the determined temperature of the fluid.

Example 8K. The method of example 7K, wherein the temperature sensor is located on the elongated body.

Example 9K. The method of example 1K, further comprising determining, with the processing circuitry, the density parameter of the fluid based on the at least one flow parameter and an estimated temperature of the fluid.

Example 10K. The method of example 9K, further comprising estimating the estimated temperature of the fluid based on a sensed body temperature of a patient in which the elongated body is at least partially inserted.

Example 11K. The method of any of examples 1K-10K, further comprising: determining the density parameter of the patient based on the sensed at least one flow parameter of the fluid, and determining a hydration status of a patient based on the determined density parameter, the elongated body being at least partially inserted within the patient.

Example 12K. The method of any of examples 1K-11K, further comprising: transmitting, with a first ultrasonic sensor, a first ultrasonic signal in a first direction through the fluid flowing distally within the lumen; and transmitting, with a second ultrasonic sensor, a second ultrasonic signal in a second direction through the fluid flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor.

Example 13K. The method of any of examples 1K-13K, wherein the elongated body comprises a Foley catheter.

Example 1L. A system comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a sensor located on the elongated body, the sensor configured to sense at least one flow parameter of a fluid within the lumen; processing circuitry configured to determine at least one of a density parameter or a temperature parameter of the fluid in the lumen based on the sensed at least one flow parameter of the fluid; and a temperature sensor configured to determine a temperature of the fluid within the lumen, wherein the processing circuitry is configured to determine the density parameter of the fluid based on the at least one flow parameter and the determined temperature of the fluid.

Example 1M. A catheter system, comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; at least one sensor configured to be coupled to the elongated body, the at least one sensor configured to sense one or more parameters of a fluid within the lumen of the elongate body; and memory configured to be coupled to the elongated body, the memory configured to store sensor calibration information, wherein the system is configured to calibrate the at least one sensor based on the sensor calibration information stored by the memory.

Example 2M. The system of example 1M, wherein the sensor calibration information is specific calibration information for the elongated body and/or the at least one sensor.

Example 3M. The system of any of examples 1M-2M, wherein the at least one sensor is a flow sensor configured to sense a flow rate of the fluid in the lumen.

Example 4M. The system of example 3M, wherein the flow sensor comprises: a first temperature sensor configured to sense a first temperature of the fluid at a first location in the lumen; a second temperature sensor configured to sense a second temperature of the fluid at a second location in the lumen, the first location being proximal to the second location; and a heating member located proximal to the second temperature sensor, the heating member configured to heat the fluid within the lumen; wherein the flow sensor determines the flow rate based on the first temperature, the second temperature and the sensor calibration information.

Example 5M. The system of example 4M, wherein the sensor calibration information includes at least one of manufacturing variances in the dimensions of the lumen, a position of the heating member on the elongated body, a position of the first temperature sensor on the elongated body, a position of the second temperature sensor on the elongated body, manufacturing variances of the heating member, manufacturing variances of the first temperature sensor, manufacturing variances of the second temperature sensor or a constitution of the substance of interest within the lumen.

Example 6M. The system of example 1M, wherein the at least one sensor is a flow sensor configured to sense a flow rate of the fluid with the lumen.

Example 7M. The system of example 6M, wherein the flow sensor comprises: a first ultrasonic sensor configured to transmit a first ultrasonic signal in a first direction through the fluid flowing distally within the lumen; and a second ultrasonic sensor configured to transmit a second ultrasonic signal in a second direction through the substance of interest flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor; wherein the first ultrasonic sensor is configured to receive the second ultrasonic signal transmitted through the fluid flowing in the lumen; wherein the second ultrasonic sensor is configured to receive the first ultrasonic sound transmitted through the fluid flowing in the lumen; wherein the flow sensor determines the flow rate based on a first transit time of the first ultrasonic signal, a second transit time of the second ultrasonic signal and the sensor calibration information; wherein the memory is located on the sensor that is removably coupled to the elongated body.

Example 8M. The system of example 7M, wherein the sensor calibration information may be at least one of: dimensions of the lumen, a position of the first ultrasonic sensor on the elongated body, a position of the second ultrasonic sensor on the elongated body, manufacturing variances of the first ultrasonic sensor, manufacturing variances of the second ultrasonic sensor or a constitution of the fluid in the lumen.

Example 9M. The system of example 1M, wherein the at least one sensor includes an oxygen sensor configured to sense the amount of oxygen within the fluid in the lumen.

Example 10M. The system of example 9M, wherein the oxygen sensor comprises: a fluorescence material configured to be located within the lumen with the fluid in the lumen; a light source configured to emit light to expose the fluorescence material to the emitted light, wherein the fluorescence material within the fluid is configured to fluoresce when exposed to the light in the lumen; and a light detector configured to detect the fluorescence of the fluorescence material, wherein the device is configured to detect oxygen in the fluid within the lumen based on the detected fluorescence.

Example 11M. The system of example 11M, wherein the sensor calibration information may be at least one of: dimensions of the lumen, fluorescing properties of the fluoresce material, manufacturing variances of the fluoresce material, manufacturing variances of the light source or manufacturing variances of the light receptor.

Example 12M. The system of any of examples 1M-11M, wherein the elongated body comprises a Foley catheter.

Example 13M. The system of any of examples 1M-12M, wherein the memory is stored on the at least one sensor.

Example 14M. The system of any of examples 1M-12M, wherein the memory is separate from the at least one sensor.

Example 1N. A method comprising: sensing, with at least one sensor configured to be coupled to an elongated body defining a lumen the elongated body comprising a proximal portion and a distal portion, one or more parameters of a fluid within the lumen of the elongate body; storing, with a memory configured to be coupled to the elongated body, sensor calibration information; and calibrating the at least one sensor based on sensor calibration information stored by the memory.

Example 2N. The method of example 1N, wherein the sensor calibration information is calibration information specific to the at least one sensor.

Example 3N. The method of any of examples 1N-2N, further comprising sensing a flow rate of the substance of interest in the lumen where the at least one sensor is a flow sensor.

Example 4N. The method of example 3N, further comprising: sensing, with a first temperature sensor, a first temperature of the substance of interest at a first location in the lumen; sensing, with a second temperature sensor, a second temperature of the substance of interest at a second location in the lumen, the first location being proximal to the second location; and heating, with a heating member located proximal to the second temperature sensor, the substance of interest within the lumen; determining, with the flow sensor, the flow rate based on the first temperature, the second temperature and the sensor calibration information.

Example 5N. The method of example 1N, further comprising sensing, with a flow sensor, a flow rate of a liquid with the lumen.

Example 6N. The method of example 5M, further comprising: transmitting, with a first ultrasonic sensor, a first ultrasonic signal in a first direction through the substance of interest flowing distally within the lumen; and transmitting, with a second ultrasonic sensor, a second ultrasonic signal in a second direction through the substance of interest flowing distally within the lumen, the second ultrasonic sensor being positioned on the elongated body proximal to the first ultrasonic sensor; receiving, with the first ultrasonic sensor, the second ultrasonic signal transmitted through the substance of interest flowing in the lumen; receiving, with the second ultrasonic sensor, the first ultrasonic sound transmitted through the substance of interest flowing in the lumen; determining, with the flow sensor, the flow rate based on a first transit time of the first ultrasonic signal, a second transit time of the second ultrasonic signal and the sensor calibration information.

Example 7N. The method of example 1N, further comprising sensing, with an oxygen sensor, the amount of oxygen within a substance of interest in the lumen.

Example 8N. The method of example 7N, further comprising: emitting, with a light source, light to expose a fluorescence material configured to be located within the lumen with the substance of interest in the lumen, wherein the fluorescence material within the substance of interest is configured to fluoresce when exposed to the light in the lumen; and detecting, with a light detector, the fluorescence of the fluorescence material; and detecting, with the oxygen sensor, oxygen in the substance of interest within the lumen based on the detected fluorescence.

Example 1O. A catheter system, comprising: an elongated body defining a lumen, the elongated body comprising a proximal portion and a distal portion; an anchoring member positioned on the proximal portion of the elongated body; a flow sensor configured to sense a flow rate of the fluid in the lumen; an oxygen sensor configured to sense the amount of oxygen within the fluid in the lumen; and memory configured to be coupled to the elongated body, the memory configured to store sensor calibration information, wherein the system is configured to calibrate the flow sensor and/or the oxygen sensor based on the sensor calibration information stored by the memory.

Example 2O. The system of example 1O, wherein the memory is configured to be coupled to one of the flow sensor or the oxygen sensor.

The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic QRS circuitry, as well as any combinations of such components, embodied in external devices, such as physician or patient programmers, stimulators, or other devices. The terms “processor” and “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry, and alone or in combination with other digital or analog circuitry.

For aspects implemented in software, at least some of the functionality ascribed to the systems and devices described in this disclosure may be embodied as instructions on a computer-readable storage medium such as RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. The instructions may be executed to support one or more aspects of the functionality described in this disclosure.

In addition, in some respects, the functionality described herein may be provided within dedicated hardware and/or software modules. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components. Also, the techniques may be fully implemented in one or more circuits or logic elements.