System for controlling a pressure support device

Abstract

The present disclosure relates to a system and method for controlling the pressure level of a gas mixture delivered to a patient via a pressure support device adapted to provide the patient with respiratory support that varies over time. More specifically, the systems and methods described herein enable accurate detection of active inspiration by the patient and fast triggering of an increased inspiratory positive airway pressure pulse. Further, the systems and methods described find particular application when the pressure support device is configured to provide a non-zero end-expiratory positive pressure, depending on the patient pressure measured along a turbulent gas flow path.

Description

Technical Field

[0001] This patent application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63 / 350,438, filed on Jun. 9, 2022, the content of which is incorporated herein by reference.

[0002] The present disclosure generally relates to systems and methods for controlling a pressure support device, and more particularly, to systems and methods for controlling the pressure level of a gas mixture delivered to a patient via a pressure support device.

Background Art

[0003] For example, positive pressure support devices, such as ventilators and continuous positive airway pressure (“CPAP”) machines, are a type of medical device that supports the breathing of patients with respiratory disorders. In some of these devices, such as CPAP machines, the gas flow is supplied to the patient at a constant pressure level, so the operation of such devices does not need to be synchronized with the patient's breathing. In other devices, such as ventilator systems, the patient's breathing is supported by delivering a gas flow at a pressure level that varies over time. More specifically, pressure support pulsates at a higher inspiratory positive airway pressure (“IPAP”) pressure level during inspiration and at a lower positive end-expiratory pressure (“PEEP”) pressure level during exhalation.

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a result, the operation of such devices must be synchronized with the patient's active breathing in order to ensure proper respiratory support. Additionally, the methods used to determine the optimal time to trigger a pressure pulse are highly dependent on the type and design of the ventilator system, as well as the availability of sensor data.

Means for Solving the Problems

[0005] According to one embodiment of the present disclosure, a system for controlling the pressure level of a gas mixture being delivered to a patient is provided. The system includes one or more processors in communication with a ventilation system, and when executed by the one or more processors, causes the system to: (1) receive a patient pressure signal from a pressure sensor of the ventilation system; (2) generate one or more pressure triggers by: (a) determining a differential signal based on the patient pressure signal, (b) determining a smoothed differential signal based on the patient pressure signal and / or the differential signal, and (c) extracting one or more pressure triggers based on the smoothed differential signal, wherein the one or more pressure triggers indicate an active inspiration phase of the patient's respiration; and (3) supply to the ventilation system an instruction for modifying the pressure level of the gas mixture being delivered to the patient based on the one or more pressure triggers, and may have a memory storing instructions that cause the above-described operations to be performed.

[0006] In one aspect, the system is configured to continuously receive the patient pressure signal over a plurality of respiratory cycles of the patient.

[0007] In one aspect, the pressure trigger is generated within 500 milliseconds for each active inspiration phase of the plurality of respiratory cycles of the patient.

[0008] In one aspect, the one or more pressure triggers are not generated during any exhalation phase of the plurality of respiratory cycles of the patient.

[0009] In one aspect, the instruction provided to the ventilation system includes increasing the pressure level of the gas mixture being delivered to the patient to a higher inspiratory airway positive pressure over a period of time.

[0010] In one aspect, generating the one or more pressure triggers further includes applying a predetermined smoothing factor to determine the smoothed differential signal, and applying a predetermined gradient limit and a predetermined minimum inspiration duration to the smoothed differential signal to extract the one or more pressure triggers.

[0011] In one aspect, each of the one or more pressure triggers corresponds to a time during which the smoothed differential signal is below the predetermined gradient limit for at least the predetermined minimum inspiratory duration.

[0012] According to another embodiment of the present disclosure, a ventilation system for delivering a gas mixture to a patient is provided. The ventilation system can have a gas supply source, a gas delivery line operably connected to the gas supply source, and a patient airway interface operably connected to the gas delivery line and defining a gas flow path from the gas supply source to the patient. The patient airway interface can have a patient pressure sensor and one or more entrainment apertures along the gas flow path, and the one or more entrainment apertures are configured to allow the patient to breathe ambient air. The ventilation system includes one or more processors adapted to control at least the delivery of the gas mixture from the gas supply source to the patient via the gas flow path, and when executed by the one or more processors, cause the ventilation system to: (1) deliver a gas mixture to the patient at a first pressure level via the patient airway interface and the gas flow path; (2) receive a patient pressure signal from the patient pressure sensor; (3) (a) determine a differential signal based on the patient pressure signal, (b) determine a smoothed differential signal based on the patient pressure signal and / or the differential signal, and (c) extract one or more pressure triggers based on the smoothed differential signal, wherein the one or more pressure triggers indicate an active inspiratory phase of the patient's respiration; and (4) change the pressure level of the gas mixture being delivered to the patient based on the one or more pressure triggers. The ventilation system further includes a memory storing instructions to cause the above-described operations.

[0013] In one aspect, the delivery of the gas mixture through the gas flow path and the patient airway interface creates a negative pressure region within the gas flow path at the one or more entrainment apertures.

[0014] In one aspect, the patient pressure sensor is disposed along the gas flow path in proximity to the negative pressure region generated by delivering a gas mixture through the gas flow path and the patient airway interface.

[0015] In one aspect, the first pressure level is the positive end-expiratory pressure greater than zero.

[0016] In one aspect, the pressure level of the gas mixture being delivered to the patient is changed by increasing the pressure level from a first pressure level to a second pressure level, the second pressure level being a higher positive inspiratory pressure.

[0017] In one aspect, a combination of at least the gas mixture from the gas source and air drawn through one or more inlet openings provides ventilation support to the patient.

[0018] According to yet another embodiment of the present disclosure, a method for controlling a ventilation system attached to a patient is provided. The method includes: (1) delivering a gas mixture to the patient at a first pressure level via a patient airway interface and a gas flow path of the ventilation system; (2) receiving a patient pressure signal of the patient using a patient pressure sensor disposed along the gas flow path proximate to a negative pressure region generated by the delivery of the gas mixture; (3) generating one or more pressure triggers by: (a) determining a differential signal based on the patient pressure signal, (b) determining a smoothed differential signal by applying a predetermined smoothing factor to the patient pressure signal and / or the differential signal, and (c) extracting one or more pressure triggers based on the smoothed differential signal by applying a predetermined gradient limit and a predetermined minimum inspiration duration to the smoothed differential signal, wherein the one or more pressure triggers indicate an active inspiration phase of the patient's breathing; (4) supplying an instruction to the ventilation system to change a pressure level of the gas mixture delivered to the patient based on the one or more pressure triggers; and (5) changing the pressure level of the gas mixture delivered to the patient over a period of time based on the supplied instruction, wherein the pressure level is changed by increasing the pressure level of the gas mixture delivered to the patient over the period of time to a higher inspiratory airway positive pressure.

[0019] In one aspect, the patient pressure signal is continuously received from the patient pressure signal over a plurality of breathing cycles of the patient, one or more pressure triggers are generated for each active inspiration phase of the plurality of breathing cycles of the patient, and the gas mixture is delivered to the patient at a higher inspiratory positive pressure within a time period of within 500 milliseconds of each active inspiration phase of the plurality of breathing cycles of the patient.

[0020] These and other aspects of various embodiments will become apparent from and be elucidated with reference to the embodiments described hereinafter.

Brief Description of the Drawings

[0021] In the drawings, like reference numerals generally refer to the same parts throughout the different views. Also, the drawings are not necessarily drawn to scale, and instead, emphasis is placed on illustrating the principles of the various embodiments.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25A

Figure 25B

[0022] The present disclosure relates to a system and method for controlling a pressure support device. More specifically, the present disclosure relates to a system and method for controlling the pressure level of a gas mixture delivered to a patient via a pressure support device adapted to provide time-varying respiratory support to the patient. As described herein, the system and method enable pressure pulse control that is triggered only during the active inspiration phase of the patient's respiratory cycle (i.e., never triggered during the expiration phase), and all inspiration phases that meet certain criteria are supported by a pressure pulse, and the trigger delay (i.e., the time between detecting the active inspiration phase and triggering the pressure pulse) is 500 milliseconds or less. In addition, the system and method described herein are adapted to function based only on the measured patient pressure as described below, although it is contemplated that other techniques, methods, and devices may be used in conjunction with the measured patient pressure.

[0023] Referring to FIG. 1, a block diagram of a ventilation system 100 having an integrated pressure control subsystem 102 according to an aspect of the present disclosure is shown. When using the ventilation system 100, this ventilation system 100 is attached to the patient's respiratory system 104, and the patient breathes normally through the ventilation system 100 while receiving mechanical support via a patient airway interface 106. In an embodiment, the patient airway interface 106 may be a non-invasive interface, such as, for example, a non-invasive open nasal interface. In addition to the patient airway interface 106, the ventilation system 100 can include a gas delivery line 108 operably connected to a gas source 110 (e.g., an oxygen source 110A and / or a compressed air source 110B). At least the gas delivery line 108 and the patient airway interface 106 define a gas flow path 112 from the gas sources 110A, 110B to the patient's respiratory system 104.

[0024] In an embodiment, the ventilation system 100 further includes a patient pressure sensor 114 arranged along the gas flow path 112 and adapted to measure the pressure generated by each of the patient's respiratory cycles (e.g., inhalation and exhalation cycles). In a particular embodiment, the patient pressure sensor 114 may be arranged within the patient airway interface 106.

[0025] Referring to FIG. 2, the patient airway interface 106 can further include one or more inlet openings 202. As seen in FIG. 2, a primary flow 208 of the gas mixture is delivered through a narrow opening 204 of the patient airway interface 106 to the patient's respiratory system 104. During normal operation, the ventilation system 100 can provide ventilation support that changes over time in the form of a primary gas flow 208 (e.g., a gas mixture) delivered to the patient 104. That is, the pressure level and flow rate of the primary gas flow 208 can be varied over time via the ventilation system 100.

[0026] In one aspect, the primary gas flow 208 is delivered at a first pressure level greater than zero (i.e., the baseline pressure level). For example, during the exhalation phase of a patient's respiratory cycle, the gas flow 208 is delivered at the pressure level of positive end-expiratory pressure (“PEEP”). In certain embodiments, the first pressure level is greater than zero cmH2O and includes from about 1 cmH2O to about 10 cmH2O, from about 2 cmH2O to about 9 cmH2O, from about 3 cmH2O to about 8 cmH2O, from about 4 cmH2O to about 7 cmH2O, from about 5 cmH2O to about 6 cmH2O, and any combination of these endpoints.

[0027] Since the primary gas flow 208 is forced through the narrow opening 204 according to the present disclosure, an entrainment of ambient air 206 is generated within a portion of the patient airway interface 106. That is, the primary gas flow 112 is forced to flow along the gas flow path 112, which includes a narrow opening 204 that creates a negative pressure region 210 within the gas flow path 112 at one or more entrainment openings 202. Although it causes efficient retention of ambient air, the velocity of the primary gas flow 208 within the patient airway interface 106 becomes very high (i.e., near the speed of sound), which causes significant variations and large changes in the flow pattern within this region of the patient airway interface 106. As a result, the total gas flow to the patient cannot be measured within the patient airway interface 106 of such a ventilation system 100, and the measured patient pressure (i.e., the pressure generated by the patient's breathing) will include a significant amount of artifacts and noise.

[0028] According to certain aspects of the present disclosure, a system 300 for controlling the pressure level of a gas mixture 112 being delivered to a patient 104 is described. Referring to FIG. 3, one such system 300 is schematically shown. The pressure control system 300 can include one or more processors 302 (also referred to as a central processing unit or CPU), a machine-readable memory 304, and an interface bus 306, all of which can be interconnected and / or communicate through a system bus 308 that includes conductive circuit paths through which instructions (e.g., machine-readable signals) can travel to perform operations such as communication, tasks, and storage.

[0029] In some embodiments, the one or more processors 302 can include a high-speed data processor sufficient to execute program components, which can include various dedicated processing units known in the art. The general-purpose processor can be a microprocessor or any conventional processor, controller, microcontroller, or state machine. In some embodiments, one or more of the features described herein are implemented on components such as application specific integrated circuits (“ASICs”), digital signal processors (“DSPs”), field programmable gate arrays (“FPGAs”), or similar electronic devices.

[0030] In an embodiment, the interface bus 306 includes an input / output interface 310 configured to connect the system 300 to one or more peripheral devices (e.g., patient pressure sensor 114, pressure regulator 128, ventilation module 116, etc.), a network interface 312 configured to connect the pressure control system 300 to a communication network 316 (using network protocols such as IEEE802.3 and / or 802.11), and / or a storage interface 314 configured to authorize, communicate with, and / or connect to a plurality of machine-readable storage devices (e.g., storage device 318, removable storage devices, etc.).

[0031] In one aspect, the network interface 312 operably connects the pressure control system 300 to a communication network 316, which can include communication networks of the same type including direct interconnections, the Internet, local area networks (“LANs”), metropolitan area networks (“MANs”), wide area networks (“WANs”), wired or Ethernet® connections, wireless connections, and combinations thereof. In some embodiments, one or more user devices 320 and / or databases 322 can be connected to the pressure control system 300 via the communication network 316 and the network interface 312.

[0032] In embodiments, the memory 304 is variously implemented in one or more forms of machine-accessible and machine-readable memory, including various types of storage devices 318, random access memory 324, and read-only memory 326. In aspects, the storage device 318 can include the same including non-transitory storage media, magnetic disk storage devices, optical disk storage devices, arrays of storage devices, solid state memory devices, and combinations thereof.

[0033] In embodiments, the memory 304 can include a pressure trigger module 328 that includes a collection of programs and / or database components and / or data (e.g., data 330). In one aspect, for example, the data 330 can include one or more process variables 352 including, but not limited to, smoothing coefficients, gradient limits, and intake durations (as described below and shown in FIG. 4). Depending on the particular implementation, the pressure trigger module 328 can include software components, hardware components, and / or some combination of both hardware components and software components.

[0034] In certain embodiments, the pressure trigger module 328 can include, but is not limited to, instructions 332 having a sensor component 332, a pressure trigger component 334, and an output component 336. These components can be incorporated into the pressure control system 300, loaded from the pressure control system, loaded into the pressure control system 300, or otherwise be operably available to and from the pressure control system. Similarly, the pressure control system 300 can be incorporated into the ventilation system 100, loaded from the ventilation system, loaded into the ventilation system, or otherwise be operably available to and from the ventilation system. For example, program components can be stored in the remote storage device 318, but these program components can be loaded and / or stored in other memories such as a remote cloud storage facility accessible via a communication network (e.g., communication network 316).

[0035] The memory 304 of the pressure control system 300 can also include an operating system component 340. The operating system component 340 can be an executable program component that facilitates the operation of the pressure control system 300. Typically, the operation system component 340 is configured to facilitate access to I / O, network, and storage interfaces and can communicate with other components of the pressure control system 300.

[0036] In an embodiment, the sensor component 332 is a stored program component executed by at least one processor, such as one or more processors 302 of the pressure control system 300, for example. In particular, the sensor component 332 can be configured to measure and / or receive the patient pressure signal 342 from the pressure sensor 114 of the ventilation system 100. In an embodiment, the patient pressure signal 342 can include a plurality of respiratory cycles of the patient. That is, the patient pressure signal 342 is received continuously and / or in real time. In one aspect, each respiratory cycle of the patient can include one inhalation phase and one exhalation phase, and thus the patient pressure signal 342 can include one or more inhalation phases and one or more exhalation phases. The sensor component 332 then supplies the received patient pressure signal 342 to the pressure trigger component 334.

[0037] In an embodiment, the pressure trigger component 334 is a stored program component executed by at least one processor, such as one or more processors 302 of the pressure control system 300, for example. In particular, the pressure trigger component 334 is configured to generate one or more pressure triggers 344. Each pressure trigger 344 indicates an active inhalation phase of the patient's respiration (i.e., respiratory cycle), and thus indicates when the gas flow 208 should be delivered to the patient 104 at a higher inspiratory airway positive pressure ("IPAP") pressure level 346.

[0038] In an embodiment, the pressure trigger component 334 is configured to (i) determine a differential signal 350 based on the patient pressure signal 342, (ii) determine a smoothed differential signal 350 based on the patient pressure signal 342 and / or the differential signal 350 using one or more smoothing coefficients 402, and (iii) extract the one or more pressure triggers 344 based on the smoothed differential signal 350. In one aspect, the smoothed differential signal 350 can be determined and smoothed in one step. For example, the following operations may be performed using the patient pressure signal 342. [Number] used with [Number] Here, dPy / dt is the smoothed differential signal 350, Δt is the time step, Lf (the "LF value" 408 shown in FIG. 4) is an integer greater than zero corresponding to the number of data points to be smoothed, Co k is the smoothing coefficient 352, Py is the patient pressure signal 342, and k, i, and m are integers greater than zero.

[0039] In some embodiments, the Lf value 408 can be from about 2 to about 50, including any combination of about 5 to about 40, about 10 to about 30, about 15 to about 20, about 8 to about 32, and the endpoints thereof. However, the Lf value 408 is preferably minimized to avoid excessive trigger delay.

[0040] In an embodiment, the pressure trigger component 334 can be further configured to (iv) apply one or more predetermined gradient limits 404 to the smoothed differential signal 350, (v) apply one or more predetermined minimum inhalation durations 406 to the smoothed differential signal 350, (vii) apply one or more predetermined minimum peak distances 410 to the smoothed differential signal 350, (viii) determine one or more gradient limits 404 applied to the smoothed differential signal 350, (ix) determine one or more minimum inhalation durations 406, (xi) determine one or more minimum peak distances 410, and / or (x) determine one or more Lf values 408. In one aspect, one or more of the process variables 352 may be pre-determined or pre-set by a physician or therapist, or may be adjusted by the pressure control system 300 and / or the patient to meet the physiological needs of the patient.

[0041] In one aspect, the gradient limit 404 can be from about ±2 cmH2O / s to about ±20 cmH2O / s, including from about ±3 cmH2O / s to about ±15 cmH2O / s, from about ±5 cmH2O / s to about ±10 cmH2O / s, from about ±7 cmH2O / s to about ±9 cmH2O / s, and any combination of those points.

[0042] In one aspect, one or both of the first pressure level 348 and the second pressure level 346 (i.e., the lower PEEP pressure level 348 and the higher IPAP pressure level 346) may be predefined by a physician or therapist, or may be adjusted by the patient himself or herself. In certain embodiments, the first pressure level 348 can be from about 0.0 cmH2O to about 30 cmH2O, including from about 0.0 cmH2O to about 10 cmH2O. In one aspect, the first pressure level 348 is greater than 0.0 cmH2O and less than 30 cmH2O, or greater than 0.0 cmH2O and less than about 10 cmH2O. In further embodiments, the second pressure level 346 can be from about 2 cmH2O to about 30 cmH2O, including from about 2 cmH2O to about 20 cmH2O and from about 10 cmH2O to about 20 cmH2O. In one aspect, the second pressure level 346 is greater than the first pressure level 348.

[0043] Referring to FIGS. 5 - 17, the disclosed system and method are described and illustrated in connection with simulated data using a constant primary gas flow that results in 20 breaths per minute and a PEEP pressure level 348 of about 5.3 cmH2O for an adult suffering from chronic obstructive pulmonary disease (“COPD”). The sampling rate of the simulated data is Δt = 2 ms.

[0044] As shown in FIG. 5, the patient pressure signal (Py) 342 for a plurality of respiratory cycles during t = 10 seconds to t = 20 seconds is shown. The wide depressions or valleys correspond to the patient's inhalation phase, while the wide peaks correspond to the patient's exhalation phase. However, as described above, the patient pressure signal 342 contains a significant amount of noise, as seen by the sharp peaks and large variations, which are caused by the fluctuations in the flow pattern within the patient airway interface 106.

[0045] In certain conventional pressure support devices, the patient's muscle pressure signal can be utilized to determine when to trigger respiratory support. For example, as shown in FIG. 6, the patient pressure signal (Py) 342 shows the simulated patient's muscle pressure signal (Pmus) for approximately one respiratory cycle during t = 10 seconds to t = 13 seconds, and the trigger output signal (ASL5000 trigger) at the start of Pmus operation. The patient's muscle pressure signal (Pmus) is used to easily trigger pressure support in conventional pressure support devices, but relying primarily on the noisy patient pressure signal (Py) 342 shown in FIG. 5 is no small matter.

[0046] According to the present disclosure, the pressure control system 300 can generate and / or determine a differential signal (dPy / dt) 350 based on the patient pressure signal (Py) 342, as discussed herein. For example, the differential signal (dPy / dt) 350 shown in FIGS. 7 and 8 was determined using an Lf value = 1 (i.e., no smoothing). However, as described above, the differential signal (dPy / dt) 350 remains quite noisy. In particular, FIG. 8 shows the region from t = 8.5 seconds to t = 11.5 seconds of FIG. 7, which shows a differential signal (dPy / dt) 350 with a plurality of "valleys" 800 that may indicate the start of an active inhalation phase, even when the patient pressure signal (Py) 342 does not support such a result.

[0047] Accordingly, as described herein, the pressure control system 300 is configured to apply a smoothing process to the patient pressure signal (Py) 342 and / or the differential signal (dPy / dt) 350 to obtain a smoothed differential signal (dPy / dt) 350. For example, the differential signal (dPy / dt) 350 shown in FIGS. 9 and 10 was obtained using Lf = 16. Comparing the differential signal (dPy / dt) 350 shown in FIG. 8 with the differential signal (dPy / dt) 350 shown in FIG. 10, the differential signal (dPy / dt) 350 shown in FIG. 10 clearly contains less "noise".

[0048] Using this smoothed differential signal (dPy / dt) 350, the pressure control system 300 can then apply one or more predetermined gradient limits 404 to determine one or more pressure triggers 344 corresponding to the start of the active inspiration phase of the patient's respiratory cycle. Referring to FIG. 11, a gradient limit 404 of ±8 cmH2O / s is applied to the smoothed differential signal (dPy / dt) 350 to identify several points 1102, 1104, 1106, 1108 where the smoothed differential signal (dPy / dt) 350 falls below the lower gradient limit 404.

[0049] However, as shown in FIG. 12, the four generated pressure triggers 1202, 1204, 1206, 1208 corresponding to the four points 1102, 1104, 1106, 1108, as a result of the noisy patient pressure signal (Py) 342, still inappropriately trigger pressure support after the patient's active inspiration phase (i.e., triggers 1204, 1206, and 1208). As shown in FIG. 13, these false triggers 1302, even over a relatively short time period (i.e., from t = 8.5 seconds to t = 26 seconds), can be seen to accumulate significantly. At each of these points, the associated ventilation system 100 inappropriately triggers the delivery of gas flow at an increased pressure contrary to the patient's actual respiratory cycle.

[0050] Accordingly, in an embodiment, the pressure control system 300 can apply one or more predetermined minimum inspiration durations 406 to the smoothed differential signal (dPy / dt) 350 to extract the correct one or more pressure triggers 344. This step is illustrated with respect to FIG. 14 (showing the smoothed differential signal (dPy / dt) 350 of FIG. 11 between t = 9 seconds and t = 9.5 seconds) and FIG. 15 (showing the smoothed differential signal (dPy / dt) 350 of FIG. 11 between t = 10 seconds and t = 10.5 seconds). As shown, after the intersection point 1102, a duration 1402 follows that spans from approximately 9.066 seconds to approximately 9.359 seconds, or approximately 293 milliseconds. In contrast, as shown in FIG. 15, after the intersection points 1104, 1106, and 1108, corresponding durations 1404, 1406, and 1408 of approximately 27.3 milliseconds, approximately 11.7 milliseconds, and approximately 5.9 milliseconds follow, respectively.

[0051] Referring to FIG. 16, by applying one or more predetermined minimum inspiration durations 406, the inappropriate triggers (e.g., triggers 1204, 1206, 1208) can be excluded, leaving only the triggers (e.g., trigger 1202) that correctly correspond to the active inspiration phases of multiple respiratory cycles of the patient. In an embodiment, the minimum inspiration duration 406 may be pre-set by a physician and / or therapist, or may be determined by the pressure control system 300 as described above. In a particular aspect, the minimum inspiration duration 406 is from approximately 30 milliseconds to approximately 120 milliseconds. In the embodiment shown in FIG. 16, the minimum inspiration duration is 40 milliseconds (i.e., 20 data points obtained with a resolution of Δt = 2 milliseconds).

[0052] As shown in FIG. 17, the pressure control system 300 utilized in accordance with the present disclosure provides an appropriate trigger 1702 for a simulated patient pressure signal (Py) 342 having a total trigger delay of less than about 500 milliseconds (i.e., the time from the start of inspiration until inspiration is detected). In certain embodiments, the total trigger delay according to the present disclosure is less than about 450 milliseconds, less than about 400 milliseconds, less than about 350 milliseconds, less than about 300 milliseconds, less than about 250 milliseconds, less than about 200 milliseconds, less than about 150 milliseconds, and / or less than about 100 milliseconds.

[0053] In embodiments, it may be necessary to further apply one or more minimum peak distances 410 to the smoothed differential signal (dPy / dt) 350 before extracting one or more pressure triggers 344. In particular, when the start of the expiratory phase is detected (i.e., when the differential signal and / or the smoothed differential signal 350 is greater than a positive predetermined gradient limit 404), a minimum distance threshold 410 is applied by the pressure control system 300 to ensure an appropriate trigger for respiratory support.

[0054] For example, referring to FIGS. 18 - 24, a second simulation was performed using an ASL5000 lung simulator with a "normal adult" lung model at 15 breaths per minute and "passive exhalation". Further, as illustrated in FIG. 18, a linearly increasing primary flow that results in a "PEEP" pressure level from about 0 to about 22 cmH2O was used with a simulated sampling rate of 5 ms (i.e., Δt = 5 ms). In particular, as shown in FIG. 18, a patient pressure signal (Py) 342 was generated and the increasing primary flow (e.g., primary flow 208) caused an upward trend in the patient pressure signal (Py) 342 until about t = 160 seconds when this primary flow 208 stopped.

[0055] Similar to the examples shown in FIGS. 5 to 17, the pressure control system 300 can determine a smoothed derivative signal (dPy / dt) 350 based on the patient pressure signal (Py) 350 to initiate the extraction of one or more pressure trigger instants 344. The smoothed derivative signal (dPy / dt) 350 with respect to the patient pressure signal (Py) 350 shown in FIG. 18 is shown together with the corresponding patient pressure signal (Py) 350 in FIG. 19. In this example, the Lf coefficient = 16 was used to determine the smoothed derivative signal (dPy / dt) 350.

[0056] Next, referring to FIGS. 20 and 21, the pressure control system 300 can apply one or more gradient limits 404 and a minimum inhalation duration 406 to the smoothed derivative signal (dPy / dt) 350. Thereby, one or more pressure trigger instants 344 (e.g., pressure triggers 2102, 2104, 2106, 2108) are generated. As shown in FIG. 21, the trigger instants 2102, 2104, 2106, 2108 correspond to points 2122, 2124, 2126, 2128 when the smoothed derivative signal (dPy / dt) 350 transitions from being greater than the negative gradient limit 404 to being less than the negative gradient limit 404. Here, the gradient limit 404 is ±4 cmH2O / s and the minimum inhalation duration is at least 100 milliseconds. However, as seen in FIG. 21, the pressure trigger instants 2102, 2106 are erroneously generated even though the patient pressure signal (Py) 342 indicates that the patient is in the exhalation phases 2130, 2132. Thus, in an embodiment, a minimum peak distance 410 is applied by the pressure control system 300 to ensure proper triggering of the ventilation system 100.

[0057] In an embodiment, the minimum peak distance 410 is defined as the distance between the instant of the trigger and the previous positive peak before the smoothed differential signal (dPy / dt) 350 exceeded the positive gradient limit. For example, referring to FIG. 22, the smoothed differential signal (dPy / dt) 350 shown in FIGS. 19 to 21 is illustrated. Points 2122, 2124, 2126, 2128 where the smoothed differential signal (dPy / dt) 350 falls below the negative gradient limit 404 (i.e., -4 cmH2O / s) are shown together with points 2222, 2224, 2226, 2228 where the smoothed differential signal (dPy / dt) 350 exceeds the positive gradient limit 404 (i.e., +4 cmH2O / s). In accordance with the determination of the minimum peak distance 410, each possible pressure trigger instant 2122, 2124, 2126, 2128 can be compared with the instant immediately preceding when the smoothed differential signal (dPy / dt) 350 exceeds the positive gradient limit 404. As shown in the table below, applying the minimum peak distance 410 to points 2122, 2124, 2126, and 2128 accurately extracts points 2124, 2128 corresponding to the inhalation phase of the patient's respiratory cycle according to the patient pressure signal (Py) 342. [Table 1]

[0058] Accordingly, distances 2232, 2236 do not meet the minimum peak distance 410, whereas distances 2234, 2236 meet the requirements of the minimum peak distance 410. As shown in FIGS. 23 and 24, here, one or more trigger instants 344 extracted based on the smoothed differential signal (dPy / dt) 350 appropriately correspond to each of the inhalation phases of the patient's respiratory cycle.

[0059] In an embodiment, the minimum peak distance 410 may be pre-set by a physician and / or therapist. In a further aspect, the minimum peak distance 410 may be determined by the pressure control system 300, for example, but not limited to, based on the patient's previous respiratory cycle. In one aspect, the minimum peak distance 410 is from about 0.5 seconds to about 2 seconds, including from about 0.5 seconds to about 0.75 seconds, from about 0.75 seconds to about 1.0 seconds, from about 1.0 seconds to about 1.25 seconds, from about 1.25 seconds to about 1.5 seconds, from about 1.5 seconds to about 1.75 seconds, from about 1.75 seconds to about 2.0 seconds, and any combination of those endpoints.

[0060] Returning to FIG. 1, the ventilation system 100 can be a wearable ventilation device comprising portable gas supply sources 110A, 110B. The ventilation module 116 can include or communicate with one or more other functional accessories. For example, the control system 102 can include an interface bus (e.g., the interface bus 306 shown in FIG. 3) adapted to transmit information regarding the patient, the patient's therapy, and the performance of the ventilation system 100 to a remote location for review, analysis, remote intervention, two-way communication, and / or archival storage. In one aspect, the compliance of the patient with the treatment and / or the utilization of the treatment can be monitored and evaluated. In a further aspect, important information including, for example, the patient's respiratory rate, I:E ratio, oxygen consumption, activity level, and respiratory depth can be extracted and analyzed. In yet another aspect, the ventilation module 116 can receive information from an external source, such as program instructions for setting titration options for the output of the ventilation device to meet the patient's needs or sending commands to the patient.

[0061] In an embodiment, the oxygen source 110A and / or the compressed air source 110B can typically be included outside the ventilation module 116. In other embodiments, the oxygen source 110A and / or the compressed air source 110B are inside the ventilation module 116, for example, when the therapy is used for stationary use (at home, in a hospital, in an outpatient facility, etc.). A gas mixer 118 can be included to control the fraction of O2 delivered to the gas delivery line 108. One or more sensors, including but not limited to a pulse oximeter, a pedometer, and / or a CO2 sensor adapted to titrate the settings of the ventilation module 116 (e.g., set the accurate settings of the oxygen mixer 118 or the output of the capacity of the ventilator) to meet the physiological needs of the patient, can be included in the sensor group 120. The ventilation system 100 can also include a drug delivery system 122, an air conditioner 124 (e.g., a humidifier and / or a dehumidifier), a flow regulator 126, a pressure regulator 128, a filtration system 130, and / or a user interface 132. One or more of these components 118, 120, 122, 124, 126, 128, 130, 132 can be inside or outside the ventilation module 116.

[0062] In one aspect, the drug delivery system 122 is adapted to propel and / or deposit aerosolized drug delivery pharmacology deep within the patient's respiratory system 104 without using a carrier propellant.

[0063] In one aspect, the user interface 132 can include a display screen adapted to display information regarding the therapy, including one or more settings provided by the ventilation system 100, and is adapted to receive user input used by the control system 102 (e.g., to control one or more settings of the ventilation system 100 and / or the ventilation module 116).

[0064] Also provided herein is a method of controlling a ventilation system 100 attached to a patient. Referring to FIGS. 25A and 25B, one such method 2500 according to an aspect of the present disclosure is illustrated.

[0065] In step 2502, method 2500 can include supplying a gas mixture 208 to a patient (i.e., the patient's airway 104) via a pressure support device 100. The gas mixture 208 is delivered to the patient at a first pressure level via a patient airway interface 106 of the ventilation system 100 and a gas flow path 112.

[0066] In step 2504, method 2500 can include measuring (e.g., in real time) a patient's respiration using a pressure sensor 114. In an embodiment, the measurement can be a patient pressure signal (Py) 342. In one aspect, the patient pressure sensor 114 can be disposed along the gas flow path 112 as described above.

[0067] In step 2506, method 2500 can include receiving a patient's patient pressure signal (Py) 342. In an embodiment, the patient pressure signal (Py) 342 is received by a control system 102 of the ventilation system 100 and / or by a pressure trigger module 328 of a pressure control system 300. In one aspect, the pressure trigger module 328 may be incorporated into the control system 102 such that the ventilation system 100 has the pressure control system 300.

[0068] In step 2508, method 2500 can optionally include determining at least one smoothing factor 402 for the patient. Alternatively, one or more smoothing factors 402 may be pre-set by a physician and / or a therapist.

[0069] In steps 2510 and 2512, method 2500 can include determining a differential signal (dPy / dt) 350 based on a patient pressure signal (Py) 342, and applying a smoothing factor 402 to the differential signal (dPy / dt) 350 and / or the patient pressure signal (Py) 342. In certain embodiments, steps 2510 and 2512 may be performed simultaneously. That is, the differential signal (dPy / dt) 350 may be determined and smoothed simultaneously.

[0070] In steps 2514, 2516, and 2518, method 2500 can optionally include determining, as described above, one or more gradient limits 404, one or more minimum inspiratory durations 406, and one or more minimum peak distances 410 of the patient. Alternatively, one or more of these process variables 352 may be pre-set by a physician and / or therapist to meet the physiological needs of the patient.

[0071] In steps 2520 and 2522, method 2500 can include applying one or more process variables 352 to the smoothed differential signal (dPy / dt) 350 to extract one or more pressure triggers 344. In one aspect, the one or more pressure triggers 344 indicate an active inspiratory phase of the patient's respiration.

[0072] In step 2524, method 2500 can include the step of changing the delivery of gas flow 208. When the pressure control system 300 is external to the ventilation system 100, it is necessary to supply the ventilation system 100 with an instruction for changing the pressure level of the gas mixture 208 being delivered to the patient (in step 2524). As used herein, the term "instruction" refers to a digital signal that includes data (e.g., pressure trigger 344) in a format that enables the ventilation system 100 to know when to deliver or modify at least the pressure level of the gas flow 208. In an embodiment, the pressure level is changed by increasing the pressure level from a first pressure level 348 (i.e., a lower PEEP pressure level) to a second pressure level 346 (i.e., a higher IPAP pressure level). In one aspect, the second pressure level 346 is maintained by the ventilation system 100 over a time period corresponding to the patient's inhalation phase. In other words, when the patient starts an exhalation phase, the pressure level of the gas flow 208 is returned to the first pressure level 348 and / or to another pressure level lower than the second pressure level 346.

[0073] As described herein, the patient pressure signal (Py) 342 may be continuously received from the patient pressure sensor 114 over a plurality of patient respiratory cycles, one or more pressure triggers 344 may be generated for each active inhalation phase of a plurality of patient respiratory cycles, and the gas mixture 208 may be delivered to the patient at a higher inspiratory airway positive pressure 346 over a time period having a trigger delay of less than 500 milliseconds after the start of each active inhalation phase of a plurality of patient respiratory cycles.

[0074] All combinations of the above-described concepts and additional concepts, to be discussed in more detail below (provided such concepts are not mutually inconsistent), are also to be understood as being part of the content of the invention disclosed herein. In particular, all combinations of the content of the claims at the end of this disclosure are considered to be part of the content of the invention disclosed herein. It should also be understood that any technical terms explicitly used herein that also appear in any disclosure incorporated by reference have meanings that are most consistent with the particular concepts disclosed herein.

[0075] All definitions, as defined and used herein, are to be understood as being above and beyond dictionary definitions, definitions in documents incorporated by reference, and / or the ordinary meaning of the defined terms.

[0076] Unless otherwise clearly stated, the indefinite articles "a" and "an", as used in the specification and claims, are to be understood to mean "at least one".

[0077] The expression "and / or", as used in the specification and claims, is to be understood to mean "either or both" of the elements so combined, i.e., elements that in some cases coexist and in other cases exist alternatively. A plurality of elements listed using "and / or" are to be construed in the same way, i.e., as "one or more" of the elements so combined. Other elements may optionally exist, whether or not in relation to specifically identified elements, other than those specifically identified by the "and / or" clause.

[0078] As used in the specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" is inclusive, i.e., it includes at least one of the elements or list of elements, but can also include more than one, and optionally, additional items not in the list. For example, only terms with specific statements such as "only one of", "exactly one of", or "consisting of" when used in the claims refer to including exactly one of a plurality of elements or list of elements. Generally, the term "or" as used herein is to be construed as indicating an exclusive alternative (i.e., "one or the other", but not "both") only when followed by an exclusive term such as "either", "one of", "only one of", or "exactly one of".

[0079] As used in the specification and claims, "at least one" with respect to a list consisting of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of these elements, but not necessarily including at least one of every element specifically listed in the list of these elements, and does not exclude any combination of the elements in the list of these elements. This definition allows for the optional presence of elements other than those specifically identified within the list of elements referred to by the expression "at least one", whether or not related to specifically identified elements.

[0080] In the claims and the above specification, all transitional phrases such as, for example, "comprising", "including", "having", "containing", "involving", "holding", and "consisting of", etc., are to be understood as open-ended, i.e., they are to be construed to include but not be limited to. Only the transitional phrases "consisting of" and "consisting essentially of" are closed or semi-closed transitional phrases, respectively.

[0081] Unless otherwise explicitly stated, in any method claimed in this specification that includes two or more steps or acts, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

[0082] The above-described examples of the described subject matter can be implemented in any of a number of ways. For example, some aspects can be implemented using hardware, software, or a combination thereof. When any aspect is implemented at least in part in software, the software code can be executed on any appropriate processor or collection of processors, whether provided on a single device or computer or distributed among multiple devices / computers.

[0083] The present disclosure can be implemented as a system, method, and / or computer program product in any possible technical detail integration. The computer program product can include one or more computer-readable storage media having computer-readable program instructions thereon for causing a processor to implement aspects of the present disclosure.

[0084] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. The computer-readable storage medium can be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above-described devices. A non-exhaustive list of more specific examples of computer-readable storage media includes a floppy disk of a portable computer, a hard disk, RAM (random access memory), ROM (read-only memory), EPROM (erasable programmable read-only memory) or flash memory, SRAM (static-RAM), CD-ROM, DVD, memory stick (registered trademark), floppy (registered trademark) disk, a mechanically encoded device such as a punch card or a raised structure in a groove in which instructions are recorded, and any suitable combination of the above. A computer-readable storage medium as used herein should not be construed as being, for example, a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., an optical pulse passing through an optical fiber cable), or an electrical signal transmitted through a wire, which are themselves transient signals.

[0085] The computer-readable program instructions described herein can be downloaded to each computer / processing device from a computer-readable storage medium or can be downloaded from an external computer or an external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computer / processing device receives the computer-readable program instructions from the network and transfers the computer-readable program instructions to a computer-readable storage medium in each computer / processing device for storage.

[0086] Computer-readable program instructions for carrying out operations of this disclosure may be any combination of source code or object code written in any one or more programming languages, including, for example, assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuits, or object-oriented programming languages such as Smalltalk or C++, and procedural programming languages such as the "C" programming language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider). In some examples, an electronic circuit having, for example, a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA) can execute the computer-readable program instructions by utilizing state information of the computer-readable program instructions and personalizing the electronic circuit to perform aspects of this disclosure.

[0087] Aspects of the present disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to examples of the disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0088] Computer-readable program instructions are provided to the processor of a special-purpose computer or other programmable data processing apparatus to generate a machine that creates means for performing the functions / operations specified in the blocks of a flowchart and / or block diagram by operations that execute via the processor of the computer or other programmable processing apparatus. These computer-readable program instructions can also be stored in a computer-readable storage medium that stores instructions that cause a product including a computer, a programmable data processing apparatus, and / or other devices to function in a particular manner so as to include a product having instructions for performing the functions / operations specified in the blocks of a flowchart and / or block diagram.

[0089] Computer-readable program instructions can also be loaded onto a computer, other programmable apparatus, or other devices, and a series of operational steps performed on a computer, other programmable data processing apparatus, or other devices to perform the functions / operations specified in the blocks of a flowchart and / or block diagram can generate a computer-implemented process.

[0090] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible embodiments of systems, methods, and computer program products according to various examples of the present disclosure. In this regard, each block in the flowchart or block diagram can represent a module, segment, or portion of one or more executable instructions for implementing the specified logical function. In some alternative implementations, the functions represented by the blocks can occur out of the order shown in the figures. For example, two blocks shown in succession can, in fact, be executed substantially simultaneously, or the blocks can be executed in the reverse order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or by a combination of dedicated hardware and computer instructions.

[0091] Other implementations are within the scope of the following claims and other claims that the applicant may be entitled to.

[0092] In this specification, several inventive embodiments have been described and illustrated. However, those skilled in the art can easily conceive of various means and / or structures to perform the functions described herein and / or obtain the results and / or one or more advantages thereof. Each such variation and / or modification is considered to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will understand that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that actual parameters, dimensions, materials, and / or configurations will depend on the specific application for which the teachings of the invention are / is used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. Accordingly, the above-described embodiments are presented by way of example only, and it should be understood that inventive embodiments different from those specifically described and claimed within the scope of the appended claims and their equivalents may be practiced. The inventive embodiments of the present disclosure are directed to the individual features, systems, articles, materials, kits, and / or methods described herein. Additionally, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the inventive scope of the present disclosure if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

Claims

1. A system for controlling the pressure level of a gas mixture being delivered to a patient, the system comprising: one or more processors in communication with a ventilation system, and a memory storing instructions wherein when executed by the one or more processors, the instructions cause the system to receive a patient pressure signal from a pressure sensor of the ventilation system, determine a differential signal based on the patient pressure signal, determine a smoothed differential signal based on the patient pressure signal and / or the differential signal, and extract one or more pressure triggers based on the smoothed differential signal thereby generating the one or more pressure triggers, supply to the ventilation system instructions for changing the pressure level of the gas mixture being delivered to the patient based on the one or more pressure triggers, and the one or more pressure triggers indicate an active inspiration phase of the patient's respiration.

2. The system of claim 1, wherein the system is configured to continuously receive the patient pressure signal over a plurality of respiratory cycles of the patient.

3. The system of claim 2, wherein the pressure trigger is generated within 500 milliseconds for each active inspiration phase of a plurality of respiratory cycles of the patient.

4. The system of claim 1, wherein the one or more pressure triggers are not generated during any expiration phase of a plurality of respiratory cycles of the patient.

5. The system of claim 1, wherein the instructions supplied to the ventilation system include increasing the pressure level of the gas mixture being delivered to the patient to a higher inspiratory airway positive pressure over a period of time.

6. Generating the one or more pressure triggers further comprises applying a predetermined smoothing factor to determine the smoothed differential signal, and applying a predetermined gradient limit, a predetermined minimum inspiration duration, and / or a predetermined minimum peak distance to the smoothed differential signal to extract the one or more pressure triggers The system of claim 1.

7. The system of claim 6, wherein each of the one or more pressure triggers corresponds to a time when the smoothed differential signal falls below the predetermined gradient limit and remains below the predetermined gradient limit for at least the predetermined minimum inspiration duration.

8. In a ventilation system for delivering a gas mixture to a patient, the ventilation system comprises: a gas source, a gas delivery line operably connected to the gas source, a patient airway interface operably connected to the gas delivery line and defining a gas flow path from the gas source to the patient, the patient airway interface having a patient pressure sensor and one or more inlet openings along the gas flow path, the one or more inlet openings being configured to enable the patient to breathe ambient air, the patient airway interface, and one or more processors adapted to control at least the delivery of the gas mixture from the gas source to the patient via the gas flow path, and a memory storing instructions, the instructions, when executed by the one or more processors, cause the ventilation system to deliver a gas mixture to the patient at a first pressure level via the patient airway interface and the gas flow path; receive a patient pressure signal from the patient pressure sensor; determine a differential signal based on the patient pressure signal; determine a smoothed differential signal based on the patient pressure signal and / or the differential signal; and extract one or more pressure triggers based on the smoothed differential signal thereby generating the one or more pressure triggers; and change the pressure level of the gas mixture being delivered to the patient based on the one or more pressure triggers wherein the one or more pressure triggers indicate an active inspiration phase of the patient's breathing, the ventilation system.

9. The delivery of the gas mixture through the gas flow path and the patient airway interface creates a negative pressure region within the gas flow path at the one or more inlet openings, the ventilation system according to claim 8.

10. The patient pressure sensor is arranged along the gas flow path in proximity to the negative pressure region generated by the delivery of the gas mixture through the gas flow path and the patient airway interface, the ventilation system according to claim 9.

11. The first pressure level is an end-expiratory positive pressure greater than zero, the ventilation system according to claim 8.

12. ​ The pressure level of the gas mixture being delivered to the patient is changed by increasing the pressure level from the first pressure level to a second pressure level, the second pressure level being a higher inspiratory airway positive pressure, the ventilation system of claim 11.

13. The ventilation system of claim 8, wherein a combination of at least the gas mixture from the gas source and air drawn through the one or more inlet openings provides ventilation support to the patient.

14. A method of controlling a ventilation system attached to a patient, the method comprising: delivering a gas mixture to the patient at a first pressure level via a patient airway interface and a gas flow path of the ventilation system; receiving a patient pressure signal of the patient using a patient pressure sensor disposed along the gas flow path proximate a negative pressure region generated by the delivery of the gas mixture; determining a differential signal based on the patient pressure signal; determining a smoothed differential signal by applying a predetermined smoothing factor to the patient pressure signal and / or the differential signal; and extracting one or more pressure triggers based on the smoothed differential signal by applying a predetermined gradient limit, a predetermined minimum inspiration duration, and / or a predetermined minimum peak distance to the smoothed differential signal to generate the one or more pressure triggers, each pressure trigger corresponding to an active inspiration phase of the patient's breathing; and changing a pressure level of the gas mixture being delivered to the patient over a period of time based on the one or more pressure triggers The method, wherein the pressure level is changed by increasing the pressure level of the gas mixture being delivered to the patient from a first pressure level to a higher inspiratory airway positive pressure over the period of time.

15. The method of claim 14, wherein the patient pressure signal is continuously received from the patient pressure sensor over a plurality of breathing cycles of the patient, the one or more pressure triggers are generated for each active inspiration phase of the plurality of breathing cycles of the patient, and the delivery of the gas mixture is changed within 500 milliseconds of each active inspiration phase of the plurality of breathing cycles of the patient.

Images