Patent ID: 12226583

DETAILED DESCRIPTION

Certain embodiments and examples of medical circuit components including inspiratory limbs, segmented inspiratory limbs and multiple-zone heating are described herein. Those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed embodiments and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the disclosure herein disclosed should not be limited by any particular embodiments described herein.

The disclosure references heater wires, heating elements, and/or heaters in the context of providing heat to a conduit. Heater wire, for example, is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art (that is, it is not to be limited to a special or customized meaning) and includes, without limitation, heater strips and/or conductive elements that produce heat when electrical power is provided. Examples of such heating elements include wires made of a conductive metal (e.g., copper), conductive polymers, conductive inks printed on a surface of a conduit, conductive materials used to create a track on a conduit, and the like. Furthermore, the disclosure references conduits, limbs, and medical tubes in the context of gas delivery. Tube, for example, is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and includes, without limitation, passageways having a variety of cross-sections such as cylindrical and non-cylindrical passageways. Certain embodiments may incorporate a composite tube, which may generally be defined as a tube comprising two or more portions, or, specifically, in some embodiments, two or more components, as described in greater detail below. The segmented limbs comprising the disclosed medical tubes can also be used in breathing circuits such as a continuous, variable, or bi-level positive airway pressure (PAP) system or other form of respiratory therapy. The terms conduit and limb should be construed in a manner that is similar to tube.

When a heated, humidified breathing tube is used for an incubator (or any region where there is a temperature change, such as around radiant warmers used for burn victims, or under a blanket used by a patient), the breathing tube will pass through at least two distinct zones: a lower temperature zone (such as the one outside the incubator) and a higher temperature zone (such as the one inside the incubator). If the tube is heated along its full length, one of the zones will tend to be at an undesirable, unsuitable, or non-optimal temperature, depending on which zone is sensed (e.g., which zone contains a temperature sensor). If the heater wire is controlled to a sensor inside the incubator (such as to a patient-end temperature sensor), the section outside the incubator will tend to be too cool, which can lead to condensation. Conversely, if the heater wire is controlled to a sensor outside the incubator, the section inside the incubator will tend to be too hot, which can lead to overheated gas being provided to the patient. Accordingly, some embodiments of the present disclosure describes systems and methods that provide for control over heat in a segmented breathing tube wherein each segment has an associated sensor providing feedback to a control module. Although several embodiments are described herein with respect to two zones, such a system could also be extended to apply to uses with additional zones, segments, or regions. For example, in an embodiment comprising three temperature zones, segments of the breathing tube may be heated based at least in part on three different temperature sensors in the zones. Furthermore, the embodiments disclosed herein can control the heat delivered to a breathing tube based on a parameter at the patient-end, bypassing or ignoring one or more of the sensors at intermediate points along the tube. Moreover, the embodiments disclosed herein can control the heat delivered to a breathing tube using parameters provided by sensors including, for example and without limitation, temperature sensors, humidity sensors, flow sensors, oxygen sensors, and the like. Other embodiments, while enabling different zones to be heated to different levels, may use fewer sensors. For example, according to one embodiment, two segments are provided and a single temperature sensor is associated with the breathing tube, preferably at or towards or near a patient-end of the tube. According to this embodiment, the segments may be configured such that only a first segment is heated or both segments are heated, wherein the first segment is preferably the segment most distal from the patient in terms of the gas flow path through the tube.

A control module can monitor and control the heating temperatures. The control module can be configured to provide heat to a first section of the breathing tube in a first mode and to the entire breathing tube in a second mode using embodiments of connector assemblies described herein. The control module may detect the presence of the first and/or second section of the breathing tube. To achieve this, the presence and/or absence of one or more sections of the breathing tube may be detected, with control of properties of the gases based at least in part modified accordingly. The embodiments described herein can be used without flying leads, exposed connectors, and/or patient-end electrical connections. Flying leads as used herein include electrical connections that extend externally of the breathing tubes, internally through the breathing tubes, and incorporated, molded, or otherwise formed or included as part of the breathing tubes. The control module can be located within the humidifier or externally to it. In some embodiments, the controller is located within the humidifier to control the heater wires associated with a first segment of an inspiratory limb, a second segment of an inspiratory limb, and an expiratory limb as well as read parameters from sensors associated with the first and second segments of the inspiratory limb and/or the expiratory limb.

The control module can also adaptively change the temperature for the segments. For example, the control module can monitor temperature sensors associated with one or more segments. The monitoring can be continuous, based on intervals, or other schemes such as interrupt or event-based monitoring. For example, the monitoring of temperature sensors can be based on reading values from an analog to digital converter, determining a voltage or current, sensing a logic condition, reading thermostatic devices, measuring thermistor values, measuring resistance temperature detectors, measuring the voltage of a thermocouple, or other methods for sensing temperature, including, but not limited to the use of semiconductor junction sensor, infrared or thermal radiation sensors, thermometers, indicators, or the like. In some embodiments, the temperature sensors are thermistors.

In some embodiments, the ratio of the power delivered to the first segment of the inspiratory limb and the second segment of the inspiratory limb can change during use based at least in part on feedback from sensor(s). For example, the ratio of power can be changed in a manner such that each segment is heated to a temperature to reduce or eliminate condensation. As a further example, the ratio of power can be changed so that overheated gas is not provided to the patient. In some embodiments, the ratio of power can be continuously changed based on feedback from sensor(s) (e.g., temperature sensors, humidity sensors, oxygen sensors, flow sensors, etc.). The ratio of power can be changed in different ways. For example, the ratio of power can be changed by altering the amplitude of a power signal (including, without limitation, the voltage and/or current), the duration of the power signal, the duty cycle of the power signal, or other suitable changes to the power signal. In an embodiment, the ratio of power is changed by altering the magnitude of the current provided.

Some embodiments provide for an inspiratory limb comprising heater wires that are not within the gas path, but are contained within a material that separates them from the gas path and that also insulates them from an external environment. In some embodiments, the circuitry used to provide power to heater wires and to read sensor(s) is internal to the inspiratory limb such that it is not exposed to the external environment. In some segmented tube embodiments, the heater wire is molded into the inspiratory or expiratory tube such that the ends of the heater wires in complementary segments of the tube contact an intermediate connector such that the heater wires electrically couple to the intermediate connector, wherein the intermediate connector can be configured to provide circuitry for heater wire control and/or sensor readings. In some embodiments, a duty cycle of a power source applied to a heater wire can be modified or varied to alter an amount of heat delivered to a gas as it flows along the associated segment.

Some embodiments described herein provide for a respiratory humidification system that is configured to deliver warm, humidified gas to a patient or other user. The gas is passed through a liquid chamber which is filled with a liquid (e.g., water) that is heated using a heater plate. The liquid evaporates in the chamber and combines with the gas which flows over it, thereby heating and/or humidifying the gas. The humidified gas can be directed to an inspiratory limb having one or more heater wires associated therewith. The heater wires can be selectively powered to provide a defined, desired, appropriate, or selected amount of heat to the humidified gas. In some embodiments, the respiratory humidification system can be used in conjunction with an incubator or radiant warmer. The inspiratory limb can be segmented such that a first segment is outside the incubator and a second segment is inside the incubator. Furthermore, a first set of heater wires can be associated with the first segment and a second set of heater wires can be associated with the second segment. The humidification system can be configured to provide power to the first set of heater wires in a first mode and to the first set and second set of heater wires in a second mode. In some embodiments, the humidification system can be configured to provide power to the first set of heater wires in a first mode and to the second set of heater wires in a second mode. The inspiratory limb can include sensors at the end of each segment or one segment to provide feedback to the humidification system for use in selecting a power to deliver to the sets of heater wires in the segments. In some embodiments, the humidification system can include an expiratory limb having associated heater wires which are also selectively controlled by the humidification system. In this application, the segmented limb is described with reference to an inspiratory limb. However, the described features can be applied to an expiratory limb, as well as other medical tubes.

Respiratory Humidification Systems

FIG.1shows a respiratory system1which can include, but is not limited to, the following components: a pressurized gases source2, such as a blower or ventilator, adapted to generate a supply of gases to be delivered to a patient3; a humidification device4adapted to condition the supply of gases; a medical tube6adapted to deliver the gases to a patient interface8, which then delivers the gases to the patient3; and a connector16adapted to connect the medical tube6to the humidification device4.

The patient interface8as described herein may refer to a mask, nasal mask, nasal prongs, oral mask, tracheal mask, or nasal pillows.

The humidification device4as described herein may refer to any device that conditions gases. This may include heating the gases and/or humidifying the gases.

Gases as described herein may refer to air, oxygen, carbon dioxide, or a mixture of any such gases, or a combination of any such gases with one or more medicaments or aerosols that may be delivered to the patient3via the patient interface8.

The medical tube6as described herein may refer to a tube, conduit, circuit, or hose. The medical tube6may comprise one or more wires. The one or more wires may comprise at least one heater wire, at least one sensor wire, and/or any other type of electrical conductor. The one or more wires may be within the medical tube6. The one or more wires may be lying along an inner or outer surface of the medical tube6. The one or more wires may be spirally wound onto the medical tube6or into the medical tube6such that the one or more wires may be embedded in the wall of the medical tube6.

The medical tube6is preferably heated. The medical tube6may include insulation to reduce condensate from forming within the medical tube6. Condensate may form if heated, humidified gases within the medical tube6cool down during transit. To reduce or eliminate condensate formation, the medical tube6may be heated. This heating may be provided by the one or more wires comprising one or more heater wires.

A terminating portion of the medical tube6may be provided to terminate the one or more wires at a connector16such that an electrical connection may be formed between the medical tube6and a component of the respiratory system1. The connector16may provide a pneumatic connection between the medical tube6and a component of the respiratory system1. A component of the respiratory system1as described herein may refer to a patient interface or a humidification device. The connector16may provide either one of or both an electrical and pneumatic connection between the medical tube6and a component of the respiratory system1.

The one or more wires may also comprise one or more sensing wires. The one or more sensing wires may be used to sense gases properties such as temperature, flow, humidity, or pressure. In some embodiments, the one or more sensing wires may be used to sense temperature. In some embodiments, the one or more sensing wires may be connected to one or more sensors that may be used to sense one or more of these gases properties.

FIG.2illustrates another example respiratory humidification system100for delivering humidified gas to a user, the respiratory humidification system100having a breathing circuit200that includes a segmented inspiratory limb202with sensors204a,204bin each segment. The segmented inspiratory limb202can be used in conjunction with an incubator208, as illustrated, or with another system where there are different temperatures along different segments of the inspiratory limb202, such as in conjunction with a radiant warmer. The segmented inspiratory limb202can be used to provide different levels of heat to different segments of the inspiratory limb202a,202bto reduce or prevent condensation and/or to control a temperature of gas delivered to a user.

The respiratory humidification system100comprises a pressurized gas source102. In some implementations, the pressurized gas source102comprises a fan, blower, or the like. In some implementations, the pressurized gas source102comprises a ventilator or other positive pressure generating device. The pressurized gas source102comprises an inlet104and an outlet106.

The pressurized gas source102provides a flow of fluid (e.g., oxygen, anesthetic gases, air or the like) to a humidification unit108. The fluid flow passes from the outlet106of the pressurized gas source102to an inlet110of the humidification unit108. In the illustrated configuration, the humidification unit108is shown separate of the pressurized gas source102with the inlet110of the humidification unit108connected to the outlet106of the pressurized gas source102with a conduit112. In some implementations, the pressurized gas source102and the humidification unit108can be integrated into a single housing.

While other types of humidification units can be used with certain features, aspects, and advantages described in the present disclosure, the illustrated humidification unit108is a pass-over humidifier that comprises a humidification chamber114and an inlet110to the humidification chamber114. In some implementations, the humidification chamber114comprises a body116having a base118attached thereto. A compartment can be defined within the humidification chamber116that is adapted to hold a volume of liquid that can be heated by heat conducted or provided through the base118. In some implementations, the base118is adapted to contact a heater plate120. The heater plate120can be controlled through a controller122or other suitable component such that the heat transferred into the liquid can be varied and controlled.

The controller122of the humidification unit108can control operation of various components of the respiratory humidification system100. While the illustrated system is illustrated as using a single controller122, multiple controllers can be used in other configurations. The multiple controllers can communicate or can provide separate functions and, therefore, the controllers need not communicate. In some implementations, the controller122may comprise a microprocessor, a processor, or logic circuitry with associated memory or storage that contains software code for a computer program. In such implementations, the controller122can control operation of the respiratory humidification system100in accordance with instructions, such as contained within the computer program, and also in response to internal or external inputs. The controller122, or at least one of the multiple controllers, can be located with the breathing circuit, either attached to the breathing circuit or integrated as part of the breathing circuit.

The body116of the humidification chamber114comprises a port124that defines the inlet110, and a port126that defines an outlet128of the humidification chamber114. As liquid contained within the humidification chamber114is heated, liquid vapor is mixed with gases introduced into the humidification chamber114through the inlet port124. The mixture of gases and vapor exits the humidification chamber114through the outlet port126.

The respiratory humidification system100includes a breathing circuit200comprising the inspiratory limb202connected to the outlet128that defines the outlet port126of the humidification unit108. The inspiratory limb202conveys toward a user the mixture of gases and water vapor that exits the humidification chamber114. The inspiratory limb202can include a heating element206positioned along the inspiratory limb202, wherein the heating element206is configured to reduce condensation along the inspiratory limb202, to control a temperature of gas arriving at the user, to maintain humidity of the gas, or any combination of these. The heating element206can raise or maintain the temperature of the gases and water vapor mixture being conveyed by the inspiratory limb202. In some implementations, the heating element206can be a wire that defines a resistance heater. By increasing or maintaining the temperature of the gases and water vapor mixture leaving the humidification chamber114, the water vapor is less likely to condensate out of the mixture.

The respiratory humidification system100can be used in conjunction with an incubator208. The incubator208can be configured to maintain a desired environment for a user within the incubator208, such as a selected, defined, or desired temperature. Within the incubator208, therefore, an interior ambient temperature may be different than a temperature outside the incubator208. Thus, the incubator208causes, defines, creates, or maintains different temperature zones along the inspiratory limb202, where the interior temperature is typically hotter than the exterior temperature. Having at least two different temperature zones along the inspiratory limb202can create problems during delivery of gas to a user such as condensation along the inspiratory limb202, delivering a gas that has a temperature that is too high, or both.

The respiratory humidification system100can include an expiratory limb210with associated heating element212. In some embodiments, the expiratory limb210and the inspiratory limb202can be connected using a suitable fitting (e.g., a wye-piece). In some embodiments, the respiratory humidification system100can be used in conjunction with a radiant warmer, under a blanket, or in other systems or situations that create two or more temperature zones. The systems and methods described herein can be used with such systems and are not limited to implementations incorporating incubators.

The inspiratory limb202can be divided into segments202aand202bwhere a first segment202acan be a portion of the inspiratory limb202that is outside the incubator208and a second segment202b(e.g., an incubator extension), can be a portion of the inspiratory limb202that is inside the incubator208. The first and second segments202a,202bcan be different lengths or the same length. In some embodiments, the second segment202bcan be shorter than the first segment202a, and, in certain implementations, the second segment202bcan be about half as long as the first segment202a. The first segment202a, for example, can have a length that is at least about 0.5 m and/or less than or equal to about 2 m, at least about 0.7 m and/or less than or equal to about 1.8 m, at least about 0.9 m and/or less than or equal to about 1.5 m, or at least about 1 m and/or less than or equal to about 1.2 m. The second segment202b, for example, can have a length that is at least about 0.2 m and/or less than or equal to about 1.5 m, at least about 0.3 m and/or less than or equal to about 1 m, at least about 0.4 m and/or less than or equal to about 0.8 m, or at least about 0.5 m and/or less than or equal to about 0.7 m.

The segments of the inspiratory limb202a,202bcan be coupled to one another to form a single conduit for gas delivery. In some embodiments, the first segment202acan include one or more first heater wires206aand one or more first sensors204aand can be used without the second segment202b. The controller122can be configured to control the first heater wires206aand read the first sensor204awithout the second segment202bbeing coupled to the first segment202a. Furthermore, when the second segment202bis coupled to the first segment202a, the controller122can be configured to control the first and second heater wires206a,206band read the first and second sensors204a,204bin their respective segments. In some embodiments, the controller122can be configured to control the respective first and second heater wires206a,206band to read the respective first and second sensors204a,204bwhen the second segment202bis attached; and to control the first heater wires206aand to read the first sensor204awhen the second segment202bis not attached, without modification to the controller122or humidification unit108. Thus, the same controller122and/or humidification unit108can be used whether the inspiratory limb202includes both the first and second segments202a,202bor only the first segment202a. In some embodiments, the controller122can be further configured to control the heater wires212in the expiratory limb210without modification to the controller122or humidification unit108. Accordingly, the respiratory humidification system100can function with or without the second segment202battached and/or with or without the expiratory limb210attached.

In some embodiments, the first and second segments202a,202bare permanently joined together to form a single conduit for gas delivery. As used here, permanently joined can mean that the segments202a,202bare joined together in a manner that makes it difficult to separate the segments, such as through the use of adhesives, friction fits, over-molding, mechanical connectors, and the like. In some embodiments, the first and second segments202a,202bare configured to be releasably coupled. For example, the first segment202acan be used for gas delivery without the second segment202b, or the first and second segments202a,202bcan be coupled together to form a single conduit for gas delivery. In some embodiments, the first and second segments202a,202bcan be configured such that they can be coupled together in only one configuration. For example, the first segment202acan have a defined chamber-end (e.g., an end closest to the chamber114or humidification unit108along a direction of the flow of the humidified gas to the patient) and a defined patient-end (e.g., an end closest to the patient along a direction of the flow of the humidified gas to the patient) wherein the chamber-end is configured to couple to components at the chamber114and/or humidification unit108. The second segment202bcan have a defined chamber-end and a defined-patient end wherein the chamber-end is configured to only couple to the patient-end of the first segment202a. The chamber-end of the first segment202acan be configured to not couple with either end of the second segment202b. Similarly, the patient-end of the first segment202acan be configured to not couple with the patient-end of the second segment202b. Similarly, the patient-end of the second segment202bcan be configured to not couple with either end of the first segment202a. Accordingly, the first and second segments202a,202bcan be configured to be coupled in only one way to form a single conduit for gas delivery. In some embodiments, the first and second segments202a,202bcan be configured to be coupled in a variety of configurations. For example, the first and second segments202a,202bcan be configured to not include a defined patient-end and/or a defined chamber-end. As another example, the first and second segments202a,202bcan be configured such that the patient-end and/or the chamber-end of the first segment202acan couple to either the chamber-end or the patient-end of the second segment202b. Similarly, the first and second segments202a,202bcan be configured such that the chamber-end and/or the patient-end of the second segment202acan couple to either the chamber-end or the patient-end of the second segment202b.

The respiratory humidification system100can include an intermediate connector214that can be configured to electrically couple elements of the first and second segments202a,202bof the inspiratory limb202. The intermediate connector214can be configured to electrically couple the heater wires206ain the first segment202ato the heater wires206bin the second segment202bto enable control of the heater wires206a,206busing the controller122. The intermediate connector214can be configured to electrically couple the second sensor204bin the second segment202bto the first sensor204ain the first segment to enable the controller122to acquire their respective outputs. The intermediate connector214can include electrical components that enable selective control of the heater wires206a,206band/or selective reading of the sensors204a,204b. For example, the intermediate connector214can include electrical components that direct power through the first heater wires206ain a first mode and through the first and second heater wires206a,206bin a second mode. The electrical components included on the intermediate connector214can include, for example and without limitation, resistors, diodes, transistors, relays, rectifiers, switches, capacitors, inductors, integrated circuits, micro-controllers, micro-processors, RFID chips, wireless communication sensors, and the like. In some embodiments, the intermediate connector214can be configured to be internal to the inspiratory limb202such that it is substantially shielded from external elements (e.g., less than 1% of the water, particulates, contaminates, etc. from an environment external to the inspiratory limb202contacts the intermediate connector214). In some embodiments, some of the electrical components on the intermediate connector214can be configured to be physically isolated from the humidified gas within the inspiratory limb202to reduce or prevent damage that may result from exposure to humidity. In some embodiments, the intermediate connector214can include relatively inexpensive passive electrical components to reduce cost and/or increase reliability.

The inspiratory limb202can include sensors204a,204bin respective segments of the inspiratory limb202a,202b. The first sensor204acan be positioned near an end of the first segment202a, close to the incubator208so that the parameter derived from the first sensor204acorresponds to a parameter of the humidified gas entering the second segment202b. The second sensor204bcan be positioned near an end of the second segment202bso that the parameter derived from the second sensor204bcorresponds to a parameter of the humidified gas delivered to the patient or user. The output of the sensors204a,204bcan be sent to the controller122as feedback for use in controlling power delivered to the heating elements206a,206bof the segments of the inspiratory limb202a,202b. In some embodiments, one or both of the sensors204a,204bcan be temperature sensors, humidity sensors, oxygen sensors, flow sensors, or the like. A temperature sensor can be any suitable type of temperature sensor including, for example and without limitation, a thermistor, thermocouple, digital temperature sensor, transistor, and the like. The parameters provided by or derived from the sensors can include, for example and without limitation, temperature, humidity, oxygen content, flow rate, or any combination of these or the like.

The controller122can be configured to control the heater wires206aand206b, to receive feedback from the sensors204aand204b, to provide logic to control power to the heater wires206aand206b, to adjust control of the heater wires206aand206bin response to readings from the sensors204aand204b, to detect a presence of a second segment202bof the inspiratory limb202(for example, the second segment202bmay have an identification element associated therewith such as a dedicated resistor or other element specifically or predominantly used for identification purposes or an inherent characteristic of the second segment may be used, such as a thermistor have a resistance within a predetermined range), to derive parameters from the readings from the sensors204aand204b, and the like. In some embodiments, the controller122includes a power source configured to deliver electrical power to the heater wires. The power source can be a source of alternating current or direct current. In some embodiments, the controller122can receive input from a heater plate sensor130. The heater plate sensor130can provide the controller122with information regarding a temperature and/or power usage of the heater plate120. In some embodiments, the controller122can receive input from a flow sensor132. Any suitable flow sensor132can be used and the flow sensor132can be positioned between ambient air and the humidification chamber114or between the pressurized gas source102and the humidification chamber114. In the illustrated system, the flow sensor132is positioned on the inlet port124of the humidification chamber114.

Detection of the presence of the second segment may be used to alter the control of the apparatus. For example, control algorithms adapted for providing humidified gases to an infant inside an incubator may be used. Thus, applicable temperature profiles and/or values and/or ranges may be used and flow and/or pressures of the gases delivered may be adjusted.

Breathing Circuit Hardware Configurations

FIG.3illustrates an example diagram of a hardware configuration800for a breathing circuit200having a first segment202aof an inspiratory limb, a second segment202bof the inspiratory limb, and may include an expiratory limb (not shown) or exhaled gases may be vented to the atmosphere. The hardware configuration800can include a humidifier108configured to couple the wiring of the heater wires HW1, and the wiring for sensor204. In some embodiments, the sensor cartridge802can be configured to couple the wiring of the heater wires HW1and the wiring for sensor204. The heater wires HW1can be controlled in two modes. In a first mode, the first heater wires206areceive electrical power while the second heater wires206bdo not. In a second mode, the first and second heater wires206a,206breceive electrical power.

The hardware configuration800can include an intermediate printed circuit board (PCB)214that includes a power diode D1The intermediate PCB214can include heat pads to dissipate heat generated by the diode D1to reduce the effects on the sensor204. The hardware configuration800can include a patient-end PCB804having two heater wires and a sensor204, wherein the heater wires206bare directly electrically coupled. In the first mode of operation, electrical power can be provided to HW1such that current flows through heater wires206aand through diode D1while substantially no current flows through heater wires206b(e.g., less than 1% of the current through heater wires206aflows through heater wires206b). In the second mode of operation, electrical power can be provided to HW1such that current flows through heater wires206aand206b. The first and second modes of operation can be controlled at least in part by the direction of the current flow through the heater wires HW1.

In some embodiments, the sensor cartridge802can be located within the humidification system100or external to the system.

FIG.4illustrates an example diagram of a hardware configuration900for an inspiratory limb6of a respiratory system1that may include an expiratory limb (not shown) or exhaled gases may be vented to the atmosphere. The hardware configuration900can include a humidifier4configured to couple the wiring of the heater wires HW1, and the wiring for sensor204. In some embodiments, the sensor cartridge802can be configured to couple the wiring of the heater wires HW1and the wiring for sensor204.

The hardware configuration900can include a patient-end PCB804having two heater wires and a sensor204, wherein the heater wires206are directly electrically coupled. Electrical power can be provided to HW1such that current flows through heater wires206and generate heat.

Other configurations, including embodiments in which an expiratory limb is heated and/or where one or more additional sensors are provided, can be derived without invention from PCT/NZ2013/00208 but implementing the novel sensor reading control disclosed herein.

Embodiments of the systems shown inFIGS.1-4may include a sinusoidal pulse width modulation (SPWM) driver that provides for turning a heater plate and heater wires ON or OFF, the heater plate for heating the contents of a humidification chamber and the heater wires being, for example, the heater wires HW1of an inspiratory conduit. The driver may supply, for example, two 100-bit patterns, one for the heater plate and one for the heater wire. Each bit in a bit pattern may cause the SPWM driver to switch the respective heater ON or OFF. Switching may be done at each falling zero crossing of the mains voltage to reduce the stress on the power supply that would be caused by an abrupt transition from zero power to the maximum power level. The choice of falling edge or rising edge is somewhat arbitrary, what is important is that the switch occurs at the zero crossing and only every full AC cycle. Thus, the heaters can be switched ON or OFF 50 times per second (every 20 ms) or 60 times per second (every 16.67 ms) for 50 Hz mains and 60 Hz mains, respectively. This is useful because the sensor, e.g. a patient-end thermistor, measurement cycle can be aligned with the mains cycle, the mains and heater wire cycles already being aligned.

FIG.5is a chart showing the relationship between the mains AC cycle and the heater wire cycles of the heater wires depicted inFIGS.3and4.

FIG.6is a chart depicting measurement of sensors with respect to the mains voltage waveform. When the falling zero crossing occurs on the mains cycle, various setup steps may be taken to prepare for the sensor reading, including switching the polarity on the sensing wire to positive. As the rising zero occurs on the mains cycle, the measurement is taken and the polarity on the sensing wire is reversed. The falling zero crossing and frequency may be detected by analyzing the mains voltage with the rising zero crossing being predicted.

CONCLUSION

Examples of respiratory humidification systems with sensor reading control and associated components and methods have been described with reference to the figures. The figures show various systems and modules and connections between them. The various modules and systems can be combined in various configurations and connections between the various modules and systems can represent physical or logical links. The representations in the figures have been presented to clearly illustrate principles related to providing sensor reading control, and details regarding divisions of modules or systems have been provided for ease of description rather than attempting to delineate separate physical embodiments. The examples and figures are intended to illustrate and not to limit the scope of the inventions described herein. For example, the principles herein may be applied to a respiratory humidifier as well as other types of humidification systems, including surgical humidifiers. The principles herein may be applied in respiratory applications as well as in other scenarios where a temperature of gases is to be controlled along multiple segments subject to varying ambient temperatures.

As used herein, the term “processor” refers broadly to any suitable device, logical block, module, circuit, or combination of elements for executing instructions. For example, controllers, as referred to herein, can include any conventional general purpose single- or multi-chip microprocessor such as a Pentium® processor, a MIPS® processor, a Power PC® processor, AMD® processor, ARM® processor, or an ALPHA® processor. In addition, controllers can include any conventional special purpose microprocessor such as a digital signal processor or a microcontroller. The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein can be implemented or performed with a general purpose processor, 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, or can be a pure software in the main processor. For example, logic module504can be a software-implemented function block which does not utilize any additional and/or specialized hardware elements. Controllers can be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a combination of a microcontroller and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Data storage can refer to electronic circuitry that allows data to be stored and retrieved by a processor. Data storage can refer to external devices or systems, for example, disk drives or solid state drives. Data storage can also refer to fast semiconductor storage (chips), for example, Random Access Memory (RAM) or various forms of Read Only Memory (ROM), which are directly connected to a communication bus or controller. Other types of data storage include bubble memory and core memory. Data storage can be physical hardware configured to store data in a non-transitory medium.

Although certain embodiments and examples are disclosed herein, inventive subject matter extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses, and to modifications and equivalents thereof. Thus, the scope of the claims or embodiments appended hereto is not limited by any of the particular embodiments described herein. For example, in any method or process disclosed herein, the acts or operations of the method or process can be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations can be described as multiple discrete operations in turn, in a manner that can be helpful in understanding certain embodiments; however, the order of description should not be construed to imply that these operations are order dependent. Additionally, the structures described herein can be embodied as integrated components or as separate components. For purposes of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not necessarily all such aspects or advantages are achieved by any particular embodiment. Thus, for example, various embodiments can be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as can also be taught or suggested herein.

Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z each to be present. As used herein, the words “about” or “approximately” can mean a value is within +10%, within +5%, or within ±1% of the stated value.

Methods and processes described herein may be embodied in, and partially or fully automated via, software code modules executed by one or more general and/or special purpose computers. The word “module” refers to logic embodied in hardware and/or firmware, or to a collection of software instructions, possibly having entry and exit points, written in a programming language, such as, for example, C or C++. A software module may be compiled and linked into an executable program, installed in a dynamically linked library, or may be written in an interpreted programming language such as, for example, BASIC, Perl, or Python. It will be appreciated that software modules may be callable from other modules or from themselves, and/or may be invoked in response to detected events or interrupts. Software instructions may be embedded in firmware, such as an erasable programmable read-only memory (EPROM). It will be further appreciated that hardware modules may comprise connected logic units, such as gates and flip-flops, and/or may comprised programmable units, such as programmable gate arrays, application specific integrated circuits, and/or processors. The modules described herein can be implemented as software modules, but also may be represented in hardware and/or firmware. Moreover, although in some embodiments a module may be separately compiled, in other embodiments a module may represent a subset of instructions of a separately compiled program, and may not have an interface available to other logical program units.

In certain embodiments, code modules may be implemented and/or stored in any type of computer-readable medium or other computer storage device. In some systems, data (and/or metadata) input to the system, data generated by the system, and/or data used by the system can be stored in any type of computer data repository, such as a relational database and/or flat file system. Any of the systems, methods, and processes described herein may include an interface configured to permit interaction with users, operators, other systems, components, programs, and so forth.

It should be emphasized that many variations and modifications may be made to the embodiments described herein, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims. Further, nothing in the foregoing disclosure is intended to imply that any particular component, characteristic or process step is necessary or essential.