Patent Description:
During normal breathing, mucous membranes which line the upper airway heat and humidify the inspired air so that it is at or near body temperature (<NUM> degrees C) with about <NUM>% relative humidity when it enters the lungs. However, when a patient is undergoing mechanical ventilation, the inspiratory gases may be delivered through an invasive artificial airway device (such as an endotracheal tube or tracheostomy tube) such that they bypass much of the mucosal tissue of the upper airway, or sometimes through non-invasive airway devices, such as those used to deliver Continuous Positive Airway Pressure (CPAP) and high flow therapies. Because inspired gases delivered from mechanical ventilators can be relatively cold and dry, it is typically desirable to heat and humidify the inspired gases before they enter the lungs. Insufficient humidification of the inspired gases can lead to clinically significant loss of body heat and water, with resultant inspissation of airway secretions, hypothermia and impaired pulmonary gas exchange due to alveolar atelectasis. In patients receiving mechanical ventilation, heating and humidification of the inspired gases is usually accomplished by either a heat and moisture exchanger (HME) or a heater/humidifier (HH). With either of these systems, it is generally desirable to ensure that the inspired gas contains at least about <NUM> of water for each liter of inspired gas delivered at <NUM> + <NUM>° C. Generally, HME's are used only for short periods of time (less than <NUM> hours), such as during transport of an intubated patient or during postoperative anesthesia recovery.

HH's are typically used when longer term mechanical ventilation is required or when use of an HME is contraindicated. HME's are passive humidification systems wherein a hygroscopic filter (e.g., hygroscopic foam or paper material that may be treated with salts) positioned at the out end of the artificial airway retains heat and moisture as the patient exhales. On the next inspiratory cycle, the dry and cold inspired gases from the ventilator are heated and humidified by the heat and moisture retained in the HME from previously exhaled breaths. HH's are active humidification and heating systems in which heat and vapor generating apparatus are used to add controlled amounts of heat and humidity to inspired gases as they are delivered to the patient. Cold and dry inspired gases from the ventilator pass through a humidification apparatus where water vapor (and some heat) is added to the inspired gases. In some cases, a heated wire is placed in the inspiratory conduit to maintain the temperature of the inspired gases and to minimize water condensation as the inspired gases are delivered to the patient airway.

An important aspect of any modern HH system is the precision with which a user may control the operation of the humidifying and heating apparatus and monitor the temperature and humidity of inspired gases at critical locations in the respiratory circuit. One commercially available HH system is the MR850 Respiratory Humidifier (Fisher & Paykel Healthcare, Auckland, New Zealand). This system compromises a humidifier that has a heater and a water chamber and a control panel, a heating wire positioned in the inspiratory conduit of the ventilation circuit and temperature sensors for monitoring temperature at the humidifier and at the patient airway end of the inspiratory conduit. The control panel includes a digital temperature display capable of displaying only one temperature at a time and several control buttons (e.g., a power on/off button, mode button and mute button) which the user must know how to manipulate in specific ways in order to bring about specific desired outcomes.

Other examples of HH systems and/or components thereof are described in <CIT>) entitled Humidifier System; <CIT>) entitled Heated Respiratory Therapy Humidifier; <CIT>) entitled Humidity Controller; <CIT>) entitled Humidifier System for Artificial Respiration; <CIT>) entitled Humidity Controller;<CIT>) entitled Control of Humidifier Chamber Temperature for Accurate Humidity Control. <CIT>) describes a humidifier system including a humidifier chamber, heater assembly, and microprocessor. The humidifier system is adapted to provide air at nearly <NUM> percent relative humidity and at a predetermined temperature to a patient. The humidifier chamber includes a continuous spiral heat exchange path which extends between a vapor storage chamber and an outlet of the humidifier chamber at which an air heating tube is connected, so that outgoing air can be delivered to the patient. The control circuitry includes a pair of sensors which are responsive to the temperature of the outgoing humidified air at the humidifier chamber outlet and at the patient end of the heating tube. The temperatures sensed are used to control the energization of both the heater assembly and a heating element of the heating tube, so that humidified air can be delivered to the patient at the predetermined temperature and with minimal condensate rainout. Other example systems are disclosed in <CIT> entitled Humidification breathing control and <CIT> entitled Humidification apparatus having RFID tag sensor at patient end of gas pathway.

There exists a need in the art for the development of new HH systems having enhanced control and monitoring capabilities for improved patient ventilation, safety and ease of use.

The present invention provides systems for delivering respiratory gas to a patient in accordance with the appended claims. The system generally includes a humidifier which has a chamber, a heating element and an outlet; an inspiratory conduit having a chamber end connectable to the outlet of the humidifier and a patient end connectable to a patient airway apparatus; a heating member extending through or along at least a substantial portion of the inspiratory conduit; at least one airway sensor located at a patient airway sensor location at or near the patient end of the inspiratory conduit, said airway sensor being operative to sense the temperature and/or humidity of respiratory gas at or near the patient end of the inspiratory conduit; at least chamber end sensor located at a chamber sensor location and operative to sense temperature and/or humidity of respiratory gas at or near the chamber of the humidifier and a controller having a user interface configured to display a system diagram which includes the humidifier, inspiratory conduit, patient end sensor location, currently sensed airway temperature at the patient airway sensor location, chamber end sensor location, and currently sensed chamber temperature at the chamber sensor location, the controller being configured to be programmed with default setting values for target chamber temperature and a target airway temperature, the controller being further configured to permit a user to manually override the assigned default target chamber temperature setting by manually inputting a target chamber temperature setting that differs from the assigned default target chamber temperature setting but is within a predetermined acceptable setting range and to override the assigned default target airway temperature setting by manually inputting a target airway temperature setting that differs from the assigned default target airway temperature setting but is within a predetermined acceptable setting range, the controller being programmed to control the amount of heat delivered by the heating member so as to cause the sensed airway temperature to be equal to or within a predetermined acceptable variance range of the target airway temperature setting and the sensed chamber temperature to be equal to or within a predetermined acceptable variance range of the target chamber temperature setting. The user interface, which may be a touch screen display, may be operative to allow a user to either accept default temperature and humidity setting and/or to input manual temperature and/or humidity settings to the controller within a clinically desired range. The controller is programmed to then control the amount of humidity delivered by the humidifier and/or the amount of heat delivered by the heating member based on the default or manually input settings.

As non-limiting examples of the present disclosure, this patent application includes the following figures:.

The following detailed description and the accompanying drawings to which it refers are intended to describe some, but not necessarily all, examples or embodiments of the disclosure. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The contents of this detailed description and the accompanying drawings do not limit the scope of the invention in any way. The invention is limited by the scope of the annexed claims.

The accompanying drawings show examples of interactive and non-interactive content displayed on a touch screen type user interface of an H&H system of the present disclosure.

As shown in <FIG>, basic components of an H&H system <NUM> of the present disclosure may include a humidifier device <NUM>, an inspiratory gas heating element <NUM>, at least one humidity sensor <NUM> (e.g., Dickson TM325 High Accuracy Remote Probe Temperature & Humidity Logger), at least first, second and third temperature sensors <NUM>, <NUM> and <NUM> (e.g., Dickson TM325 High Accuracy Remote Probe Temperature & Humidity Logger or Dickson SM425 High Accuracy Temperature Logger with Platinum RTD Probe) and a controller/user interface <NUM> as described below.

The humidifier device <NUM> typically comprises a chamber <NUM> which has an inlet <NUM> and an outlet <NUM> and a humidifier heating element <NUM> (e.g., a heated plate) which heats liquid that has been placed in the chamber <NUM>.

In typical operation, the inspiratory gas heating element <NUM> is positioned in or on an inspiratory gas conduit IGC. One end of the inspiratory gas conduit IGC is connected to the outlet <NUM> of the humidifier chamber <NUM>. The other end of the inspiratory gas conduit ISG is connected to a patient airway device PAD. The patient airway device PAD can be any type of non-invasive or invasive device for delivering inspiratory gases to a patient. Examples of non-invasive patient airway devices include face masks<NUM>, nasal masks, nasal cannulae, nasal plugs, breathing tents, etc. Examples of invasive patient airway devices include all manner of insertable or indwelling breathing conduits such as endotreacheal tubes, endobroncheal tubes, nasotracheal tubes, tracheostomy tubes, supraglottic airways (SGA), laryngeal mask airways (LMA), mouthpieces, etc.
<NUM> The term "face mask" as used herein includes basic face masks which fit loosely over the patient's mouth and nose as well as more specialized, tightly-fitting face masks used for delivery of certain modes of assisted ventilation such as continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP).

A quantity of desired liquid, such as sterile water, is placed in the chamber <NUM>. The inlet <NUM> of the chamber <NUM> is connected to a source of inspiratory gas, which may simply be a source of compressed room air or oxygen-enriched room air or ventilation device, such as a mechanical ventilator, CPAP machine, BiPAP machine, anesthesia machine, etc..

As the humidifier heating element <NUM> heats the liquid within the chamber <NUM>, the liquid vaporizes. The vapor then mixes with (i.e., humidifies) inspiratory gases which enter the chamber <NUM> through inlet <NUM>. Humidified inspiratory gases then exit the chamber <NUM> through outlet <NUM> and travel through the inspiratory gas conduit IGC to the patient airway device PAD and into the patient's lungs. The inspiratory gas heating element <NUM> may be used to maintain or control the temperature of the humidified inspiratory gases as they travel through the inspiratory gas conduit IGC.

The first temperature sensor <NUM> may be positioned so as to sense the temperature of the humidifier heating element <NUM> (e.g., the surface temperature of a heated plate at the base of the humidifier chamber). The second temperature sensor <NUM> may be positioned to sense the temperature of humidified inspiratory gases exiting the chamber <NUM> or within the inspiratory gas conduit IGC at or near its connection to the chamber outlet [<NUM>] <NUM>. The third temperature sensor <NUM> may be positioned within the inspiratory gas conduit IGC at or near its connection to the patient airway device PAD.

The humidity sensor <NUM> may be positioned within the inspiratory gas conduit IGC at or near its connection to the patient airway device PAD. Optionally, additional humidity sensor(s) may be positioned at one or more additional locations in the inspiratory gas conduit IGC or chamber <NUM>.

The controller/user interface <NUM> may comprise a programmable microprocessor <NUM> of a type generally known in the art (e.g. Intel Corporation, Mountain View, California; Advanced Micro Devices, Inc. , Sunnyvale, California) connected to or having touch screen type user interface <NUM> of a type generally known in the art (e.g., Palm Technology Co. , Kaohsiung City Taiwan, R. As described in more detail below, the controller <NUM> is in wired or wireless communication with, and receives data signals from, the humidity sensor(s) <NUM> and temperature sensors <NUM>, <NUM> and <NUM>. The controller <NUM> also receives settings or other information that is input by a user via the user interface <NUM>. The controller <NUM> is in wired or wireless communication with at least the humidifier heating element <NUM> and inspiratory gas heating element <NUM> and is programmed to control the temperature of the humidifier heating element <NUM> and inspiratory gas heating element <NUM> in response to settings and/or other information input by the user and feedback from the humidity sensor(s) <NUM> and/or temperature sensors <NUM>, <NUM> and <NUM>.

<FIG> through 2D are examples of some of the mode selection screens that may appear on a touch screen user interface <NUM> of the H&H system <NUM>. As seen in <FIG>, the user is initially presented with a "Select Mode" screen whereby the user may touch selection icons for either heated wire <NUM> or non-heated wire <NUM>. Whichever icon <NUM>, <NUM> is pressed by the user will illuminate and will signal the controller <NUM> to operate in either heated mode or non-heated mode. <FIG> shows, for example, the manner in which the touch screen will appear immediately after the user has selected and pressed the "heated wire" icon <NUM>. Thereafter, as seen in <FIG>, additional touch screen icons will appear to allow the user to select either invasive <NUM> or non-invasive <NUM>. The invasive mode icon <NUM> will be selected and will become illuminated if the patient airway device PAD is of an invasive type and the non-invasive icon <NUM> will be selected and will become illuminated if the patient airway device PAD is of a non-invasive type. <FIG> shows, for example, the manner in which the touch screen will appear immediately after a user has selected and pressed the heated wire icon <NUM> and invasive airway icon <NUM>. This signals the controller to operate in these selected modes.

<FIG> show examples of some of the operational screens that may appear on the touch screen after the user has selected the heated wire and invasive modes. After those modes have been selected, a complete heated/invasive system diagram 20i will appear as seen in <FIG>. This system diagram shows schematic images of: a ventilation device <NUM>, humidifier <NUM>, invasive patient airway device 28i, first inspiratory gas conduit <NUM> running from the ventilation device <NUM> to the inlet of the humidifier <NUM>, second inspiratory gas conduit running from the humidifier outlet to the invasive patient airway device 28i, an exhalation conduit <NUM> running from the invasive patient airway device 28i to the ventilation device <NUM>, a first temperature sensor icon <NUM> showing the sensed temperature of the humidifier heating element (e.g., heating plate), a second temperature sensor icon <NUM> showing the sensed temperature the humidified inspiratory gases at or near the location where the second inspiratory gas conduit <NUM> connects to the outlet of the humidifier <NUM>, a third temperature sensor icon <NUM> showing the sensed temperature of humidified inspiratory gases at or near the location at which the second inspiratory gas conduit <NUM> connects to the invasive patient airway device 28i, a humidity sensor icon <NUM> showing the sensed humidity of humidified inspiratory gases at or near the location at which the second inspiratory gas conduit <NUM> connects to the invasive patient airway device 28i and a setting change icon <NUM> which may be touched by the user if it is desired to change any of the operational settings such as target temperature or humidity settings.

If the user touches the setting change icon <NUM>, a passcode entry screen 20a will appear as shown in <FIG>. The user then uses keypad <NUM> to enter a passcode and the entered passcode appears in passcode screen <NUM>, as illustrated in <FIG>. The user then touches either the clear or confirm icon <NUM> depending on whether the user believes the correct passcode to have been entered. If the entered passcode does not match an acceptable passcode that has been programmed to the controller, an incorrect passcode indicator <NUM> will appear as seen in <FIG>.

If the entered passcode does match an acceptable passcode that has been programmed to the controller, a secure setting modification screen will appear as seen in <FIG>. That secure setting modification screen shows a first column of default setting icons <NUM> which display the default settings for patient airway temperature 62i (i.e., the temperature of humidified inspired gases at or near the location at which the second inspiratory gas conduit <NUM> connects to the invasive patient airway device 28i as sensed by the third temperature sensor), humidifier temperature <NUM> (i.e., the temperature of humidified inspired gases at or near the location at which the second inspiratory gas conduit <NUM> connects to the outlet of the humidifier as sensed by the second temperature sensor) and patient airway humidity <NUM> (i.e., the relative humidity of humidified inspired gases at or near the location at which the second inspiratory gas conduit <NUM> connects to the invasive patient airway device 28i as sensed by the humidity sensor). Adjacent to each of these default setting icons <NUM> is a column of corresponding manual setting icons <NUM>. Each of the manual setting icons <NUM> has an associated raise setting icon <NUM>, an associated lower setting icon <NUM> and a manual setting override indicator <NUM>. Initially, the default temperature and humidity settings will appear in both the default setting icons <NUM> and manual setting icons <NUM> and the manual setting override icons will not be illuminated. If the user wishes to manually override any of the default settings, the user will selectively touch either the raise icon <NUM> or lower icon <NUM> to cause the desired manual override setting to appear in each manual setting icon <NUM> for which manual override of the default setting is desired with illumination of the associated manual override indicator icon <NUM>, within the clinically acceptable range. In at least some embodiments, the manual override indicator <NUM> may emit different signal modalities (e.g., different colors of light) to indicate different states or conditions. For example, the manual override indicator <NUM> may emit green light when the user has selected a manual override setting that is within an acceptable range for that variable. However, if the user selects a manual override value that is outside of the acceptable range, the manual override indicator <NUM> may emit red light and/or the processor may cause the input manual override value to stop at or adjust to the closest value that is within the acceptable range (i.e., the subject manual setting icon <NUM> will stop at or automatically adjust to the lowest value in the acceptable range when the user attempts to enter a setting that is below the acceptable range and will stop at or automatically adjust to the highest value in the acceptable range when the user attempts to enter a setting that is above the acceptable range.

After manual override settings within the acceptable range have been entered, the user touches the accept icon <NUM> and the controller will then reset to the manual override settings and the touch screen display will once again show the schematic diagram of the system as indicated in <FIG>. The user may then observe the sensed temperatures and humidity displayed by icons <NUM>, <NUM>, <NUM> and <NUM> as described above. If any of the sensed temperatures or humidity deviate more than a pre-determined amount from the settings that have been entered to the controller, the controller will cause an alarm icon <NUM> to illuminate and (optionally) a corresponding audible or other alarm signal may be emitted. This may occur as an alarm if any sensed temperature or humidity changes by a pre-programmed significant amount for an unexpected reason and not if the user is trying to manually select a temperature or humidity outside of the limited range that is provided as a choice.

The controller may be programmed to cause the alarm icon <NUM> to illuminate and/or emit an audible or other suitable signal if any sensor reading is different than what is selected/default setting. Also, the controller may cause the area of concern (i.e., whichever sensed value that has triggered the alarm) to flash or be otherwise highlighted or indicated on the touch screen display. Also, in at least some embodiments where the alarm emits an audible signal, the user may cause the audible signal to be muted for a period of time (e.g., one minute) by taking some volitional muting action such as by touching the alarm icon <NUM>. When so muted, the audible alarm signal may recommence after the timed muting period has expired if the problem that triggered the alarm has not been rectified.

<FIG> show the manner in which certain touch screen displays may vary from that described above if user initially selects to operate in heated wire/non-invasive mode. As shown on <FIG>, the heated wire icon <NUM> and non-invasive icon <NUM> will illuminate when touched and, thereafter, a schematic system diagram 20n will appear as seen in <FIG>. This schematic system diagram screen 20n differs from that described above in relation to <FIG> only in that a non-invasive patient airway icon 28N appears instead of an invasive patient airway icon 28i as seen in <FIG>. Also, if the user wishes to change a setting and enters a valid passcode which is accepted by the controller, a secure setting modification screen as shown in <FIG> will appear. This secure setting modification screen seen in <FIG> differs from that described above in relation to <FIG> only in that a non-invasive patient airway icon 62n appears in place of the invasive patient airway icon 62i seen in <FIG>. All other functions are the same as described above with respect to the heated wire/invasive mode of operation.

<FIG> show the manner in which certain touch screen displays may vary from that described above if user initially selects to operate in non-heated wire/invasive mode. As shown in <FIG>, the non-heated wire icon <NUM> and invasive icon <NUM> will illuminate when touched and, thereafter, a schematic system diagram 20i/n will appear as seen in <FIG>. This schematic system diagram screen 20i/n differs from that described above in relation to <FIG> only in that condensation traps 34T are shown in the second inspiratory gas conduit <NUM>. Also, if the user wishes to change a setting and enters a valid passcode which is accepted by the controller, the secure setting modification screen as shown in <FIG> will appear. This secure setting modification screen of <FIG> differs from that described above in relation to <FIG> in that the only possible manual override is for the humidifier temperature <NUM>. Since the inspired gas heating element is not operational in this mode, the default settings for patient airway temperature 62i and patient airway humidity <NUM> cannot be manually overridden. However, the controller may be programmed to automatically adjust the default settings displayed for the patient airway temperature 62i and patient airway humidity <NUM> so that they correspond to the manual setting entered by the user for humidifier temperature <NUM>. All other functions are the same as described above with respect to the heated wire/invasive mode of operation.

<FIG> show the manner in which certain touch screen displays may vary from that described above if user initially selects to operate in non-heated wire/non-invasive mode. As shown in <FIG>, the non-heated wire icon <NUM> and on-invasive icon <NUM> will illuminate when touched and, thereafter, a schematic system diagram 20n/n will appear as seen in <FIG>. This schematic system diagram screen 20n/n differs from that described above in relation to <FIG> only in that a non-invasive patient airway icon 28N appears instead of an invasive patient airway icon 28i. Also, if the user wishes to change a setting and enters a valid passcode which is accepted by the controller, a secure setting modification screen as shown in <FIG> will appear. This secure setting modification screen seen in <FIG> differs from that described above in relation to <FIG> only in that a non-invasive patient airway icon 62n appears in place of the invasive patient airway icon 62i. All other functions are the same as described above with respect to the heated wire/invasive mode of operation.

Claim 1:
A system (<NUM>) for delivering respiratory gas to a patient, said system comprising a humidifier (<NUM>) which has a heating element (<NUM>) and a chamber (<NUM>) having an outlet (<NUM>); an inspiratory conduit (IGC) having a chamber end connectable to the outlet of the humidifier (<NUM>) and a patient end connectable to a patient airway device (PAD); and a heating member (<NUM>) extending through or along at least a portion of the inspiratory conduit; said system being further provided with the combination of:
an airway temperature sensor (<NUM>) located at a patient airway sensor location within a patient end of the inspiratory conduit to sense airway temperature of respiratory gas;
a chamber end temperature sensor (<NUM>) located at a chamber sensor location to sense chamber end temperature of respiratory gas within the chamber or within a chamber end of the inspiratory conduit; and
a controller having a user interface configured to display a system diagram which includes the humidifier (<NUM>), inspiratory conduit, patient end sensor location, currently sensed airway temperature (<NUM>) at the patient airway sensor location, chamber end sensor location, and currently sensed chamber temperature (<NUM>) at the chamber sensor location;
wherein the controller is configured to be programmed with default setting values for target chamber temperature and a target airway temperature;
wherein the controller is further configured to permit a user to manually override the assigned default target chamber temperature setting by manually inputting a target chamber temperature setting that differs from the assigned default target chamber temperature setting but is within a predetermined acceptable setting range and to override the assigned default target airway temperature setting by manually inputting a target airway temperature setting that differs from the assigned default target airway temperature setting but is within a predetermined acceptable setting range;
wherein the controller is programmed to control the amount of heat delivered by the heating member so as to cause the sensed airway temperature to be equal to or within a predetermined acceptable variance range of the target airway temperature setting and the sensed chamber temperature to be equal to or within a predetermined acceptable variance range of the target chamber temperature setting.