Patent Description:
Volume clamping is a technique for non-invasively measuring blood pressure in which pressure is applied to a subject's finger in such a manner that venous flow is fully obstructed and arterial pressure may be balanced by a time varying pressure to maintain a constant arterial volume. In a properly fitted and calibrated system, the applied time varying pressure is equal to the arterial blood pressure in the finger. The applied time varying pressure may be measured to provide a reading of the patient's arterial blood pressure.

This may be accomplished by a finger cuff that is arranged around a finger of a patient. The finger cuff may include an infrared light source, an infrared sensor, and an inflatable bladder. The infrared light may be sent through the finger in which a finger artery is present. The infrared sensor picks up the infrared light and the amount of infrared light registered by the sensor may be inversely proportional to the artery diameter and indicative of the pressure in the artery.

In the finger cuff implementation, by inflating the bladder in the finger cuff, a pressure is exerted on the finger artery. If the pressure is high enough, it will compress the artery and the amount of light registered by the sensor will increase. The amount of pressure necessary in the inflatable bladder to compress the artery is dependent on the blood pressure. By controlling the pressure of the inflatable bladder such that the diameter of the finger artery is kept constant, the blood pressure may be monitored in very precise detail as the pressure in the inflatable bladder is directly linked to the blood pressure.

In a typical present day finger cuff implementation, a volume clamp system is used with the finger cuff. The volume clamp system typically includes a pressure generating system and a regulating system that includes: a pump, a valve, and a pressure sensor in a closed loop feedback system that are used in conjunction with the measurement of the arterial volume. To accurately measure blood pressure, the feedback loop provides sufficient pressure generating and releasing capabilities to match the pressure oscillations of the subject's blood pressure.

Unfortunately, present finger cuff systems rely upon very large devices, such as, rotary pumps, blower pumps, and related devices, for the pressure generating system, to generate the pneumatic pressure for the volume clamp system. Such pump devices are comparatively much larger than the finger cuff itself and are located at distant locations to provide pressure to the finger cuff. As such, these types of pumps consume significant power and are physically removed from the patient thereby creating long air paths that hinder performance and that may result in inaccurate blood pressure measurements. Further, the large pump systems and supporting hardware expand clutter and hinder mobility in the hospital, emergency room, intensive care unit (ICU), doctor's office, ambulance, and other patient care locations. Moreover, this type of large pump system requires high energy consumption as a result of the continuously operating pump and provides further disadvantages as to noise due to the pump and the regular discharge of air. These attributes of high energy use, large components, and noise are undesirable in particular health care environments, such as ambulatory use, emergency rooms, intensive care unit (ICU), examination rooms, and in hospital rooms in which measurements are performed while a patient is sleeping.

The Finapres Nano-core OEM module, developed by Finapres Medical Systems, is a non-invasive continuous blood pressure OEM module for integration into blood pressure measurement systems. The Finapres Nano-core OEM module is miniaturized so that it can be mounted to a patient's wrist. It comprises two manifolds for connecting the device with two finger cuffs, sensors and valves, inter alia for switching measurement between two fingers. In order to achieve adequate pressure dynamics with such a miniature system, the Finapres Nano-core OEM module further comprises a system consisting of a plunger and a micro pump. The Nano-core OEM module is intended to be as quiet as possible, therefore the micro pump is switched on as little as possible, only if there is a large change in the average pressure, for example if the patient is quickly moved from lying to sitting.

<CIT> provides an apparatus for measuring the blood pressure, BP, of a user, the apparatus comprising a volume-clamp BP monitoring device that comprises a first pressure device for applying pressure to a first part of the body of the user, a first photoplethysmogram, PPG, sensor for obtaining a first PPG signal from the first part of the body of the user, and a control unit that is configured to analyse the first PPG signal and to control the pressure of the first pressure device; wherein the control unit is configured to adjust the pressure of the first pressure device to maintain the first PPG signal at a constant level and to determine the BP of the user from the pressure of the first pressure device; and a second sensor, separate from the first PPG sensor, for measuring a physiological characteristic of the user in a second part of the body of the user, wherein the second part of the body is separate from the first part of the body; wherein the apparatus is configured to analyse the measured physiological characteristic to determine a measure of the blood perfusion in the second part of the body of the user, and to determine whether to perform a recalibration of the volume-clamp BP monitoring device on the basis of changes in the blood perfusion.

<CIT> provides a system and method of digital control for a blood pressure measurement system. A photo-plethysmographic (PPG) system produces a frequency signal that corresponds to the measured light in the PPG system. Such light may be indicative of blood volume in a vein or artery. The frequency signal may be used to control one or more pressure valves of the system in order to measure blood pressure and hold the frequency signal constant.

<CIT> (WO'<NUM>) provides a sphygmomanometer cuff assembly, air pump, pressure sensor and release valve are contained in an otherwise conventional computer mouse controller or are attached to a cell phone, television remote control or directly to a computer. In one example the sphygmomanometer cuff is nominally positioned within a mouse structure and is extended outside the mouse housing during the measurement. In another example, the cuff is always external of the mouse structure and is easily connected to the mouse at special ports during the measurement. In yet another example, the cuff is always internal of the mouse structure and is readily accessible through an aperture in the housing surface of the mouse to permit the measurement to take place. In yet another example, a wrist cuff and associated pump, sensor and valve are designed to be selectively connected to a cell phone to which appropriate software has been downloaded from a computer. In yet another example, the cuff and associated components are connected directly to a television remote control unit. In all of the examples shown in WO' <NUM>, the sphygmomanometer cuff is configured for receiving a human finger or wrist in circumambient pressured engagement using controlled air pressure to vary the cuff engagement pressure in a precise manner.

The invention relates to blood pressure measurement devices as defined in independent claim <NUM> that utilizes volume clamping and that are wearable by a patient and to a method for blood pressure measurement as defined in independent claim <NUM>. The blood pressure measurement device may comprise: a finger cuff attachable to the patient's finger including a light emitting diode (LED) - photodiode (PD) pair to measure a pleth signal and a bladder surrounding the finger and a blood pressure measurement controller coupled to the bladder through a finger cuff connector to provide pneumatic pressure to the bladder. The blood pressure measurement controller may be wearable by the patient. The blood pressure measurement controller may include: a pump coupled to the finger cuff connector, a valve, a pressure sensor, and control circuitry coupled to the pump, the valve, the pressure sensor, and the LED-PD pair. The control circuitry may be configured to: control the pneumatic pressure applied by the pump through the finger cuff connector to the bladder to replicate the patient's blood pressure based upon measuring the pleth signal; control the opening of the valve to release pneumatic pressure from the bladder; and measure the patient's blood pressure by monitoring the pressure of the bladder with the pressure sensor.

Embodiments of the invention may relate to a pressure regulating feedback loop for volume clamp blood pressure measurement for use with a finger cuff. The feedback loop may contain a pump for generating pressure within a bladder of the finger cuff to compress a subject's artery and a valve for releasing pressure from the bladder. The feedback loop may further contain a pressure sensor that measures pressure within the bladder of the finger cuff and a system for measuring the volume of the clamped artery, such as, by utilizing an infrared light emitting diode (LED) and photodiode (PD).

In particular, embodiments of the invention may relate to a blood pressure measurement device that utilizes volume clamping and that is wearable by a patient. The blood pressure measurement device may comprise: a finger cuff attachable to the patient's finger including a light emitting diode (LED) - photodiode (PD) pair to measure a pleth signal and a bladder surrounding the finger and a blood pressure measurement controller coupled to the bladder through a finger cuff connector to provide pneumatic pressure to the bladder. The blood pressure measurement controller may also be wearable by the patient. The blood pressure measurement controller may include: a pump coupled to the finger cuff connector, a valve, a pressure sensor, and control circuitry coupled to the pump, the valve, the pressure sensor, and the LED-PD pair. As will be described, the control circuitry may be configured to: control the pneumatic pressure applied by the pump through the finger cuff connector to the bladder to replicate the patient's blood pressure based upon measuring the pleth signal; control the opening of the valve to release pneumatic pressure from the bladder; and measure the patient's blood pressure by monitoring the pressure of the bladder with the pressure sensor.

As will be described, according to embodiments of the invention, the finger cuff may be attached to a patient's finger and a blood pressure measurement controller including a pump, a valve, and a sensor may be coupled to the patient's finger, hand, wrist, arm, or other part of the patient's body, or may not be on the patient's body but may be in close proximity to the finger cuff, for a compact and energy efficient system to monitor a patient's blood pressure.

With reference to <FIG>, an example of a blood pressure measurement device <NUM> will be described. As shown in <FIG>, the blood pressure measurement device <NUM> may include a finger cuff <NUM> having a suitable housing and a suitable finger connector (e.g., including a bladder) that may be attached to a patient's finger and a blood pressure measurement controller <NUM> that may be attached to the patient's body (e.g., a patient's hand). The blood pressure measurement device <NUM> may further be connected to a patient monitoring device <NUM> and a heart reference sensor (HRS) <NUM>. The operations of the blood pressure measurement device <NUM> including the finger cuff <NUM> and the blood pressure measurement controller <NUM> will be hereafter described in more detail.

Continuing with this example, as shown in <FIG>, a patient's hand may be placed on the face <NUM> of an arm rest <NUM> for measuring a patient's blood pressure with the blood pressure measurement device <NUM>. As will be described, the blood pressure measurement controller <NUM> of the blood pressure measurement device <NUM> may be coupled to a bladder of the finger cuff <NUM> through a finger cuff connector <NUM> in order to provide pneumatic pressure to the bladder for use in blood pressure measurement. Blood pressure measurement controller <NUM> may be coupled to the patient monitoring device <NUM> through a power/data cable <NUM> and to the HRS <NUM> through a HRS connector <NUM>. The patient monitoring device <NUM> may be any type of medical electronic device that may read, collect, process, display, etc., physiological readings/data of a patient including blood pressure, as well as any other suitable physiological patient readings. Accordingly, power/data cable may transmit data to and from patient monitoring device <NUM> and also may provide power from the patient monitoring device <NUM> to the blood pressure measurement controller <NUM> and finger cuff <NUM>. The HRS <NUM> may be placed near the patient's heart level and connected by the HRS connector <NUM> to the blood pressure measurement controller <NUM> of the blood pressure measurement device <NUM> to allow for the compensation of potential errors due to differences in height between the finger cuff <NUM> and the heart level in the calculation of blood pressure measurements.

As can be seen in <FIG>, in one example, the finger cuff <NUM> may be attached to a patient's finger and the blood pressure measurement controller <NUM> may be attached on the patient's hand with an attachment bracelet <NUM> that wraps around the patient's wrist. However, it should be appreciated that due to the small size of the blood pressure measurement controller <NUM> that a wide variety of attachment configurations may be utilized. For example, the blood pressure measurement controller <NUM> may be placed on a patient's finger (e.g., the same finger as the finger cuff <NUM> or on one or more different fingers), hand, wrist, arm, or other places such that it is mounted or placed locally to the finger cuff <NUM> in a convenient fashion. As one particular example, the blood pressure measurement controller <NUM> may be clipped to a pair of the patient other fingers (e.g., utilizing the attachment bracelet or velcro-strip).

Alternatively, the blood pressure measurement controller <NUM> may be placed not on the patient's body but may be placed or mounted in close proximity to the finger cuff <NUM>. For example, the blood pressure measurement controller <NUM> may be clamped or attached to the arm rest <NUM> (e.g., placed on a clip or be velcroed) near the finger cuff <NUM> or may simply dangle off of the finger cuff <NUM> and may not be attached to anything. By having the blood pressure measurement controller <NUM> removed from the patient's body, access to a patient's arteries and veins is freed-up. Additionally, it should be appreciated that the approximately rectangular formation of the blood pressure measurement controller <NUM> shown in <FIG> is merely a design implementation and that any suitable shape may be used. It should further be appreciated that due to the small size of the blood pressure measurement controller <NUM> that a wide variety of attachment configurations may be utilized, and these are merely examples.

As will be described in more detail hereafter, finger cuff <NUM> in conjunction with blood pressure measurement controller <NUM> that includes: a pump, a valve, a pressure sensor and control circuity; may be utilized to measure the patient's blood pressure by monitoring the pressure of the bladder with the pressure sensor and may display the patient's blood pressure on the patient monitoring device <NUM>. In particular, due to the small size of the finger cuff <NUM> and blood pressure measurement controller <NUM>, techniques are provided to monitor a patient's blood pressure with a compact, mobile, energy efficient, and low noise system.

With additional reference to <FIG> is a diagram of an example of a blood pressure measurement device, according to one embodiment of the invention.

Finger cuff <NUM> may include a light emitting diode (LED) <NUM> and a photodiode (PD) <NUM> to create an LED-PD pair. The finger cuff <NUM> including the LED-PD pair in cooperation with a bladder <NUM> that surrounds the finger and compresses or clamps against the patient's artery <NUM> may be used to measure a pleth signal to measure a patient's blood pressure, as will be described.

The blood pressure measurement controller <NUM> may be coupled to the bladder <NUM> of the finger cuff <NUM> through a finger cuff connector <NUM> to provide pneumatic pressure to the bladder <NUM>. The blood pressure measurement controller <NUM> may include a pump <NUM>, a valve <NUM>, and a sensor <NUM>. Further, blood pressure measurement controller <NUM> may include control circuity <NUM> and input/output circuitry and interfaces <NUM>, as will be described in more detail hereafter. As examples of interfaces, an interface to HRS connector <NUM> to HRS <NUM> and an interface to power/data cable <NUM> to patient monitoring device <NUM> may be utilized.

As has been described, the blood pressure measurement controller <NUM> may be wearable by a patient and may be mounted on patient's finger, hand, wrist, arm, or other part of the patient's body or may not be worn by the patient but may just be located locally to the finger cuff <NUM> (e.g., be placed on the arm rest, be dangling from the patient's finger, etc.). Further, as has been described, the blood pressure measurement controller <NUM> may be coupled to the finger cuff <NUM> by a finger cuff connector <NUM> which may be an appropriate connector <NUM> that includes a tube portion to provide pneumatic pressure from the pump <NUM> of the blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM> (as well as a cable portion to provide the LED drive to the finger cuff and the pleth signal from the finger cuff <NUM> to the control circuity <NUM>) or by a connection fixture for directly connecting pneumatic pressure from the pump <NUM> of blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM> (as well as to provide the pleth signal from the finger cuff <NUM> to the control circuity <NUM>) such that the blood pressure measurement controller <NUM> is mountable on top of the finger cuff <NUM>. Thus, blood pressure measurement controller <NUM> may be connected locally by a tube or may be directly connected on top of the finger cuff <NUM> via a connection fixture upon a user's finger. These examples will be described in more detail hereafter. Also, it should be appreciated that the finger cuff connector <NUM> electronically connects the output of the LED-PD pair to the control circuity <NUM>.

Therefore, in one embodiment, blood pressure measurement controller <NUM> may include: a pump <NUM> including an air inlet <NUM> that is coupled to the finger cuff connector <NUM> to provide pneumatic pressure to the bladder <NUM>; a valve <NUM> with a vent <NUM> coupled to the pneumatic pressure flow to release pneumatic pressure from the bladder <NUM>; a pressure sensor <NUM> coupled to the pneumatic pressure flow to monitor the pneumatic pressure of the bladder <NUM>; and control circuitry <NUM> coupled to the pump <NUM>, valve <NUM>, and sensor <NUM>. It should be appreciated that the components of the blood pressure measurement controller <NUM> may be suitably contained and interconnected within the housing of the blood pressure measurement controller <NUM> shown in <FIG>, but that any suitable housing may be utilized.

The control circuity <NUM> may be coupled to the pump <NUM>, the valve <NUM>, the sensor <NUM>, and the LED-PD pair in order to control the bladder <NUM> of the finger cuff <NUM> and to measure the pleth signal from the LED-PD pair such that the control circuitry <NUM> of the blood pressure measurement controller <NUM> can measure a patient's blood pressure.

In particular, control circuitry <NUM> may be configured to: control the pneumatic pressure applied by the pump <NUM> (e.g., from air inlet <NUM>) through the finger cuff connector <NUM> to the bladder <NUM> (e.g., denoted as output) to replicate the patient's blood pressure based upon measuring the pleth signal received from the LED-PD pair of the finger cuff <NUM>. Further, control circuitry <NUM> may be configured to: control the opening of the valve <NUM> via vent <NUM> to release pneumatic pressure from the bladder <NUM>. Additionally, control circuitry <NUM> may be configured to: measure the patient's blood pressure by monitoring the pressure of the bladder <NUM> based upon the input from the pressure senor <NUM>, which should be the same as patient's blood pressure.

The patient's measured blood pressure may be commanded by control circuitry <NUM> to be transmitted through the I/O circuitry and interface <NUM> through data/power cable <NUM> to patient monitoring device <NUM> to display the patient's measured blood pressure. Further, control circuitry <NUM> based upon input from HRS <NUM> and other sources received through the I/O circuitry and interface <NUM> through HRS connector <NUM> may allow for compensation of potential errors due to differences in height between the finger cuff <NUM> and the heart level in the calculation of blood pressure measurements.

It should be appreciated that that control circuitry <NUM> of blood pressure measurement controller <NUM> may implement a computational algorithm to control the pneumatic pressure applied by the pump <NUM> (e.g., output) through the finger cuff connector <NUM> to the bladder <NUM> to replicate the patient's blood pressure based upon the measured pleth signal received from the LED-PD pair of the finger cuff <NUM> in conjunction with controlling the opening of the valve <NUM> to release pneumatic pressure from the bladder <NUM> and measuring the patient's blood pressure by monitoring the pressure of the bladder <NUM> with the pressure sensor <NUM> and at the same time commanding the calculated blood pressure measurement to be displayed by the patient monitoring device <NUM>. Further, it should be appreciated that the pneumatic pressure applied via the pump <NUM> may be a suitable gas, such as, air, or in other implementation may utilize a suitable liquid.

With additional reference to <FIG> is a diagram of an example of a blood pressure measurement device, according to one embodiment of the invention, in which, instead of a valve that is controlled by control circuitry, as previously described, a fixed orifice <NUM> is utilized. In this example of the disclosure, the fixed orifice <NUM> including a vent <NUM> is used to passively release pneumatic pressure from the bladder <NUM> instead of the valve. Accordingly, the opening and closing of the valve is not required and control of the valve to open and close by the control circuitry <NUM> is not required, as the fixed orifice <NUM> passively releases pneumatic pressure from the bladder <NUM>. In this implementation, pneumatic pressure applied to the bladder <NUM> will be completely controlled and modulated by the pump <NUM>, as controlled by the control circuitry <NUM>, while using a fixed orifice <NUM>, that is not controlled. Examples of this fixed orifice <NUM> implementation, will be hereafter described in more detail. The rest of the components of <FIG> and their functionality are similar to the previous description of <FIG>, and will not be repeated for brevity's sake.

Examples of the types of operations implemented by the finger cuff <NUM> and blood pressure measurement controller <NUM> will be hereafter described.

With additional reference to <FIG>, a brief description of the principals of operation of the finger cuff <NUM> and the blood pressure measurement controller <NUM> and the volume clamp mode will be described. In <FIG>, the X-axis shows time (seconds) and the Y-axis shows pressure (mmHg) and pleth counts. Line <NUM> shows the pleth signal from the LED-PD pair of the finger cuff <NUM> received by the control circuity <NUM> as the pressure shown by line <NUM> in the bladder <NUM> is changed by increasing/decreasing pneumatic pressure by pump <NUM> (e.g., as measured by pressure sensor <NUM>). The pleth signal <NUM> is inversely proportional to artery volume. As can be seen on <FIG>, pressure <NUM> may be increased to the bladder <NUM> of the finger cuff <NUM> step-wise by the pump <NUM> (as measured by pressure sensor <NUM>) and the pleth signal <NUM> increases accordingly - as the artery is squeezed. The blood pressure beats are visible in the pleth signal during this rise.

In particular, as can be seen in <FIG>, control circuitry <NUM> of blood pressure measurement controller <NUM> chooses a desirable pleth signal <NUM> received from LED-PD pair and switches to a volume clamp mode, in which, the bladder pressure is controlled by pneumatic pressure applied by pump <NUM> to bladder <NUM> (as controlled by control circuitry <NUM>) to keep the pleth signal <NUM> constant by balancing the blood pressure in the artery <NUM>. For example, as can be seen by section <NUM>, the pleth signal <NUM> is constant while the pressure signal <NUM> is constantly changed. In particular, pump <NUM> is commanded by control circuitry <NUM> to variably apply pneumatic pressure through the finger cuff connector <NUM> to the bladder <NUM> of the finger cuff <NUM> and valve <NUM> through vent <NUM> is variably commanded to open to release pneumatic pressure from the bladder <NUM>, such that, in volume clamp mode, the pressure signal <NUM> applied to the bladder, as shown in section <NUM>, is equal to the patient's blood pressure (e.g., approximately <NUM>/<NUM>).

With additional reference to <FIG>, an example of the volume clamp mode will be described. In this example, the opening and closing of valve <NUM> is controlled by control circuitry <NUM>. In <FIG>, the X-axis shows time (seconds) and the Y-axis shows pressure (mmHg) and command values (e.g., <NUM>-<NUM>). For example, line <NUM> shows pressure generated in the bladder <NUM> of the finger cuff <NUM> by the pump <NUM> applying pneumatic pressure under the control of control circuitry <NUM>, as a function of time. Below the bladder pressure shown by line <NUM>, line <NUM> shows a pump drive signal commanding when pump <NUM> is turned on and how hard it is being driven (e.g., <NUM>-<NUM> command value), as commanded by control circuitry <NUM>. It should be noted that pump <NUM> is only turned on when the pressure of the bladder <NUM> is rising. Along with the pump drive signal <NUM>, a valve command signal <NUM> commanded by control circuitry <NUM> shows when valve <NUM> is commanded to be opened and how far it is commanded to be opened (e.g., <NUM>-<NUM> command value). It should be noted that valve <NUM> is only opened when pressure is dropping, as shown in <FIG>.

With additional reference to <FIG>, another example of the volume clamp mode will be described, in which, a valve controlled by control circuitry <NUM> to open and close to release pneumatic pressure from the bladder <NUM> is not utilized, and a fixed orifice <NUM> including vent <NUM> not controlled by controlled circuity <NUM>, to passively release pneumatic pressure from the bladder <NUM> is utilized. In <FIG>, the X-axis shows time (seconds) and the Y-axis shows pressure (mmHg) and command values (e.g., <NUM>-<NUM>). For example, line <NUM> shows pressure generated in the bladder <NUM> of the finger cuff <NUM> by the pump <NUM> applying pneumatic pressure under the control of control circuitry <NUM>, as a function of time. Adjacent to the bladder pressure shown by line <NUM>, line <NUM> shows a pump drive signal commanding when pump <NUM> is turned on and how hard it is being driven (e.g., <NUM>-<NUM> command value), as commanded by control circuitry <NUM>. It should be noted that pump <NUM> is turned fully on (e.g., command value <NUM>) when the pressure of the bladder <NUM> rises steeply and then the pump drive commands fluctuate up and down <NUM> at lower command levels as the bladder pressure <NUM> descends. It should be noted that no valve commands are needed as the fixed orifice <NUM> passively releases the pneumatic pressure from the bladder.

It should be appreciated that various types of pumps <NUM> may be utilized to implement the previously described embodiments of the invention. For example, in one embodiment, a piezoelectric pump may be utilized as pump <NUM>. A piezoelectric pump <NUM> may be of relatively small size, low power consumption, and may operate at high operating frequencies well outside of the human auditory range. Therefore, the piezoelectric pump <NUM> being of small size and low power consumption is suitable for use in the previously described blood pressure measurement controller <NUM> that is easily mountable on a patient's finger, hand, wrist, etc., as previously described, in very close proximity to the finger cuff <NUM>. Also, since a piezoelectric pump <NUM> is relatively quiet it does not interfere with a patient's sleep. Additionally, the piezoelectric pump's <NUM> ability to be modulated (e.g., quickly turned on and off) to control the pneumatic pressure applied to the bladder <NUM> of the finger cuff <NUM> may further minimize power usage and maximize control and efficiency.

Other types of pumps <NUM> that are of small size, low power consumption, and low sound may also be utilized, such as: a voice coil pump, a piston pump, a diaphragm pump, an electrolytic pump, or a peristaltic pump. These types of pumps may be utilized with these same types of advantages as the piezoelectric pump.

In one embodiment, valve <NUM> may be a piezoelectric valve including a vent <NUM>. Piezoelectric valves, similar to the piezoelectric pump, have the advantages of small size, low power consumption, and high actuation speeds. As one particular example, piezoelectric valve <NUM> may include a piezoceramic actuator section, a fixed beam section connected to the piezoceramic actuator section, and a rubber sleeve portion connected to the fixed beam section. The piezoceramic actuator section, the fixed beam section, and the rubber sleeve portion may be connected linearly and the rubber sleeve portion may extend over the vent <NUM>. In this way, the valve command signal from the control circuitry <NUM> may the cause the movement/actuation of the piezoceramic actuator section such that the rubber sleeve portion moves away from the vent <NUM> (opening) or over the vent <NUM> (closing) to control the opening and the closing of the vent. As previously described, as an example, a command signal (<NUM>-<NUM>) may be sent commanding how much the piezoelectric valve should be opened (e.g., how much the piezoceramic actuator section should be commanded to be moved/actuated to simultaneously move the rubber sleeve portion away from the vent to open the vent). It should be appreciated that this is just one example. Other types of valves that have similar characteristics of a piezoelectric valve (e.g., small size, low power consumption, and high actuation speeds), such as, a solenoid valve, an electromechanical valve, etc. It should be appreciated that any type of suitable valve may be utilized.

Various examples will be hereafter described that may be used to implement the previously described blood pressure measurement device that is wearable by a patient.

For example, <FIG> is a perspective view of the previously described blood pressure measurement controller <NUM>, in which, the finger cuff connector <NUM> may be a suitable connector <NUM> including a tube portion to provide the pneumatic pressure from the pump <NUM> of the blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM> (as well as a cable portion to provide the pleth signal from the finger cuff <NUM> the control circuity <NUM>). With reference also to <FIG> illustrates the components of the blood pressure measurement controller <NUM> contained in the housing of the blood pressure measurement controller <NUM>, as previously described.

As can be seen in <FIG>, the blood pressure measurement controller <NUM> may have an approximately rectangular shaped housing with curved ends and may have air inlets <NUM> at the top to provide air for pneumatic pressure generated by pump <NUM>. In this example, as has been described, connector <NUM> may be coupled to the blood pressure measurement controller <NUM> by a mounting connector <NUM>, in which, connector <NUM> may include an appropriate tube to provide the pneumatic pressure from the pump <NUM> of the blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM>. Further, blood pressure measurement controller <NUM> may be coupled to the patient monitoring device <NUM> through a power/data cable <NUM> connected by a mounting connector <NUM> and to the HRS <NUM> through a HRS connector <NUM> connected by a mounting connector <NUM>. The patient monitoring device <NUM> may be any type of medical electronic device that may read, collect, process, display, etc., physiological readings/data of a patient including blood pressure, as well as any other suitable physiological patient readings.

In this example, in which, the finger cuff connector <NUM> may be an appropriate connector <NUM> to provide the pneumatic pressure from the pump <NUM> of the blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM>, the operation of the blood controller pressure measurement controller <NUM> proceeds, as previously described. In particular, control circuitry <NUM> may be configured to: control the pneumatic pressure applied by the pump <NUM> (e.g., from air inlet <NUM>) through the connector <NUM> to the bladder <NUM> to replicate the patient's blood pressure based upon measuring the pleth signal received from the LED-PD pair of the finger cuff <NUM>. Further, control circuitry <NUM> may be configured to: control the opening of the valve <NUM> to release pneumatic pressure from the bladder <NUM>. However, in some example of the disclosure, as previously described, a valve controlled by control circuitry <NUM> to open and close to release pneumatic pressure from the bladder <NUM> is not utilized, and a fixed orifice not controlled by controlled circuity <NUM>, to passively release pneumatic pressure from the bladder <NUM> may be utilized. Additionally, control circuitry <NUM> may be configured to: measure the patient's blood pressure by monitoring the pressure of the bladder <NUM> based upon the input from the pressure senor <NUM>, which should be the same as patient's blood pressure. The patient's measured blood pressure may be commanded by the control circuitry <NUM> to be transmitted through the I/O circuitry and interface <NUM> through data/power cable <NUM> to the patient monitoring device <NUM> to display the patient's measured blood pressure. Further, control circuitry <NUM> based upon input from HRS <NUM> and other sources received through the I/O circuitry and interface <NUM> through HRS connector <NUM> may allow for compensation of potential errors due to differences in height between the finger cuff <NUM> and the heart level in the calculation of blood pressure measurements.

As another example, with reference to <FIG> is a perspective view of the previously described blood pressure measurement controller <NUM>, in which, the finger cuff connector <NUM> may be a relatively short connection fixture for directly connecting the pneumatic pressure from the pump <NUM> of blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM>. In this example, the blood pressure measurement controller <NUM> may be connected directly on top of the finger cuff <NUM> with the connection fixture such that the whole system (both the blood pressure measurement controller <NUM> and the figure cuff <NUM>) are placed directly on top of a patient's finger. It should be appreciated that the connection fixture may be any suitable form of mechanical fixture structure (e.g., metallic, plastic, etc.) that is relatively small and that has sufficient strength to securely connect the housing of the blood pressure measurement controller <NUM> to the housing of the finger cuff <NUM> and that may include a relatively small interior tube portion to provide the outputted pneumatic pressure from the pump <NUM> of the blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM> and to support a cable portion to provide the pleth signal from the finger cuff <NUM> to the control circuity <NUM>. With reference also to <FIG> illustrates the components of the blood pressure measurement controller <NUM> contained in the housing of the blood pressure measurement controller <NUM>, as previously described.

As can be seen in <FIG>, the blood pressure measurement controller <NUM> may have an approximately rectangular shaped housing with curved ends and may have air inlets <NUM> at the top to provide air for pneumatic pressure generated by pump <NUM>. In this example, as has been described, finger cuff connector <NUM> may be a connection fixture for directly connecting the pneumatic pressure from the pump <NUM> of blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM>. Further, blood pressure measurement controller <NUM> may be coupled to the patient monitoring device <NUM> through a power/data cable <NUM> connected by a mounting connector <NUM> and to the HRS <NUM> through a HRS connector <NUM> connected by a mounting connector <NUM>. The patient monitoring device <NUM> may be any type of medical electronic device that may read, collect, process, display, etc., physiological readings/data of a patient including blood pressure, as well as any other suitable physiological patient readings.

In this example, in which, the finger cuff connector <NUM> may be a connection fixture to provide the pneumatic pressure from the pump <NUM> of the blood pressure measurement controller <NUM> to the bladder <NUM> of the finger cuff <NUM>, the operation of the blood pressure measurement controller <NUM> proceeds, as previously described. In particular, control circuitry <NUM> may be configured to: control the pneumatic pressure applied by the pump <NUM> (e.g., from air inlet <NUM>) through the connection fixture <NUM> to the bladder <NUM> to replicate the patient's blood pressure based upon measuring the pleth signal received from the LED-PD pair of the finger cuff <NUM>. Further, control circuitry <NUM> may be configured to: control the opening of the valve <NUM> to release pneumatic pressure from the bladder <NUM>. However, in some example of the disclosure, as previously described, a valve controlled by control circuitry <NUM> to open and close to release pneumatic pressure from the bladder <NUM> is not utilized, and a fixed orifice not controlled by controlled circuity <NUM>, to passively release pneumatic pressure from the bladder <NUM> may be utilized. Additionally, control circuitry <NUM> may be configured to: measure the patient's blood pressure by monitoring the pressure of the bladder <NUM> based upon the input from the pressure senor <NUM>, which should be the same as patient's blood pressure. The patient's measured blood pressure may be commanded by the control circuitry <NUM> to be transmitted through the I/O circuitry and interface <NUM> through data/power cable <NUM> to the patient monitoring device <NUM> to display the patient's measured blood pressure. Further, control circuitry <NUM> based upon input from HRS <NUM> and other sources received through the I/O circuitry and interface <NUM> through HRS connector <NUM> may allow for compensation of potential errors due to differences in height between the finger cuff <NUM> and the heart level in the calculation of blood pressure measurements.

It should be appreciated that various other alternative implementations may be utilized. For example, in one alternative implementation, the valve <NUM> may simply be a fixed orifice to release pneumatic pressure from the bladder <NUM>. In this implementation, the opening and closing of the valve <NUM> will therefore not be controlled by the control circuitry <NUM>, as previously described, as it is simply an orifice. In this instance, pneumatic pressure applied to the bladder <NUM> will be completely controlled and modulated by the pump <NUM> as controlled by the control circuitry <NUM>. In another implementation, backward leakage of pneumatic pressure out of the pump <NUM> may be allowed when the pump <NUM> is powered off to allow for the release of pneumatic pressure from the bladder <NUM>.

Also, although a wired data cable <NUM> has been illustrated to transmit the measured patient's blood pressure through a wired connection to the patient monitoring device <NUM>, it should be appreciated that a wireless connection may be utilized to transmit data to and from the patient monitoring device <NUM> instead of a wired connection.

As previously described, blood pressure measurement device <NUM> utilizing a finger cuff <NUM> in conjunction with a relatively small and compact blood pressure measurement controller <NUM> that includes: an internal controllable valve <NUM>, an internal controllable pump <NUM>, and a sensor <NUM>; enables a very compact pressure drive system and feedback loop for a continuous non-invasive blood pressure monitoring system. Further, this type of blood pressure measurement device <NUM> may simply be located on the patient's wrist, hand, or finger, or may be located in close proximity thereto (e.g., the blood pressure measurement controller <NUM> may be mounted to a nearby fixture near the finger cuff <NUM> or may dangle from the finger cuff <NUM>).

Moreover, the compact size of the internal controllable pump <NUM> (e.g., a piezoelectric pump) and the internal controllable valve <NUM> (e.g., a piezoelectric valve) being utilized in the blood pressure measurement controller <NUM> closely coupled to the finger cuff <NUM> such that the blood pressure measurement device <NUM> is mountable to patient's finger, hand, wrist, etc., enables a continuous blood pressure measurement system that is portable and can be worn continuously by a patient as the patient moves through the hospital (e.g., from operating room (OR) to intensive care unit (ICU)), or from an ambulance to the emergency room (ER), ICU, etc., or between any locations in a hospital, medical, or home environment, etc. Therefore, by utilizing an internal controllable pump <NUM> (e.g., a piezoelectric pump) and an internal controllable valve <NUM> (e.g., a piezoelectric valve) in the blood pressure measurement device <NUM>, a small, compact, and portable blood pressure measurement system is provided. This type of more compact blood pressure measurement device has various advantages as to current systems, such as: provides a high-fidelity feedback loop; is less obtrusive in the OR, ER, ICU, etc.; is of lower cost; is very portable; utilizes less energy; creates less sound - is quieter; etc. In particular, in one implementation, the small size and lightweight of the previously described blood pressure measurement device allows for the easy movability of the patient around a medical facility, as well as, in and out of the medical facility.

It should be appreciated that aspects of the invention previously described may be implemented in conjunction with the execution of instructions by processors, circuitry, controllers, control circuitry, etc., such as control circuitry <NUM>, I/O circuity <NUM>, etc. As an example, control circuity <NUM> may operate under the control of a program, algorithm, routine, or the execution of instructions to execute methods or processes in accordance with embodiments of the invention previously described. For example, such a program may be implemented in firmware or software (e.g. stored in memory and/or other locations) and may be implemented by processors, control circuitry, and/or other circuitry, these terms being utilized interchangeably. Further, it should be appreciated that the terms processor, microprocessor, circuitry, control circuitry, circuit board, controller, microcontroller, etc., refer to any type of logic or circuitry capable of executing logic, commands, instructions, software, firmware, functionality, etc., which may be utilized to execute embodiments of the invention.

The various illustrative logical blocks, processors, modules, and circuitry described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a specialized processor, circuitry, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor may be a microprocessor or any conventional processor, controller, microcontroller, circuitry, or state machine.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module/firmware executed by a processor, or any combination thereof. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium.

Claim 1:
A blood pressure measurement device that is wearable by a patient, comprising:
a finger cuff (<NUM>) attachable to the patient's finger including a light emitting diode (LED) (<NUM>) - photodiode (PD) (<NUM>) pair to measure a pleth signal and a bladder (<NUM>) surrounding the finger; and
a blood pressure measurement controller (<NUM>) coupled to the bladder (<NUM>) through a finger cuff connector (<NUM>) to provide pneumatic pressure to the bladder (<NUM>), the blood pressure measurement controller (<NUM>) wearable by the patient, the blood pressure measurement controller (<NUM>) including: a pump (<NUM>) coupled to the finger cuff connector (<NUM>), a valve (<NUM>), a pressure sensor (<NUM>), and control circuitry (<NUM>) coupled to the pump (<NUM>), the valve (<NUM>), the pressure sensor (<NUM>), and the LED-PD (<NUM>, <NUM>) pair, the control circuitry (<NUM>) being configured to:
control the pneumatic pressure applied by the pump (<NUM>) through the finger cuff connector (<NUM>) to the bladder (<NUM>) to replicate the patient's blood pressure based upon measuring the pleth signal;
control the opening of the valve (<NUM>) to release pneumatic pressure from the bladder (<NUM>); and
measure the patient's blood pressure by monitoring the pressure of the bladder (<NUM>) with the pressure sensor (<NUM>);
wherein the finger cuff connector (<NUM>) includes a connection fixture for directly connecting the pneumatic pressure from the blood pressure measurement controller (<NUM>) to the bladder (<NUM>) of the finger cuff (<NUM>) and wherein the blood pressure measurement controller (<NUM>) is mountable on top of the finger cuff (<NUM>).