Description:TECHNICAL FIELD
The present disclosure generally relates to non-invasive and invasive ventilators capable of assisting physiological respiration. In particular, the present disclosure relates to system and methods for simultaneously regulating gas pressure while maintaining fraction of Oxygen (FiO2) in the Oxygen-air mixture in the inspiratory line.

BACKGROUND
The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Ventilators are medical devices used to provide supplemental oxygen support to patients. The ventilators may include a source of pressurized Oxygen and an air source fluidly connected to the patient through a conduit, to supply Oxygen-air mixture to the patient. During a controlled inhalation phase, respiratory gas (for example, Oxygen and air mixture) is supplied to the patient.
Peak inspiratory pressure (PIP) is the highest level of pressure applied to the lungs of a patient during inspiratory (Inhalation) phase of the ventilator. Positive end expiratory pressure (PEEP) is the positive pressure that remains in the airways at the end of the expiratory cycle (end of exhalation). Both the PIP and PEEP should be maintained in the ventilator during inspiratory and expiratory phase of the ventilator respectively. Further, it may be important to maintain a predetermined fraction of Oxygen (FiO2) in the Oxygen-air mixture in the inspiratory line of the mechanical ventilators during both inspiratory and expiratory phases.
Some conventional techniques attempt to maintain Peak inspiratory pressure (PIP) and Positive end expiratory pressure (PEEP) during the inspiratory and expiratory phases of ventilator respectively, without considering the Oxygen level in the inspiratory line. In some other cases, proportional integral derivative (PID) gains of flow control valves for air and Oxygen are continuously varied based on a pre-determined relationship between the errors of pressure and Oxygen and the PID gains of flow control valves for air and Oxygen. In some other cases, values of PIP and PEEP are split into individual PIP and PEEP targets respectively for air and Oxygen based on required FiO2. In some other cases, proportional integral derivative (PID) gains of flow control valves for air and Oxygen are varied in stages corresponding to pressure and Oxygen errors. In some other cases, proportional integral derivative (PID) gains of flow control valves for air and Oxygen are varied based on the set parameters for example, PID gains of flow control valves for air and Oxygen are varied based on different values of required FiO2.
Therefore, it is desired to provide a system and method for regulating gas pressures as well as maintaining the desired FiO2 in a ventilator efficiently and effectively so as to reduce discomfort and potential harm to a user of the ventilator.

OBJECTS OF INVENTION
An object of the present invention is to provide a system and method for regulating gas pressure in a ventilator during inspiratory and expiratory phases.
Another object of the present invention is to provide a system and method for regulating gas pressure in a ventilator while maintaining the required fraction of Oxygen (FiO2).
Another object of the present invention is to provide a system for effectively and accurately regulating gas pressures in a ventilator.
Another object of the present invention is to provide a system that can dynamically adapt to changes in a user’s lung parameters as well as to dynamics of the ventilator.
Another object of the present invention is to provide a system that limits discomfort to a user.

SUMMARY
The present disclosure overcomes one or more shortcomings of the prior art and provides additional advantages discussed throughout the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In a first aspect, the present disclosure provides a system for regulating gas pressure in a ventilator. The system comprises an inspiratory module configured in the ventilator and adapted to supply a ventilating gas to a user of the ventilator. The inspiratory module comprises an Oxygen source, an air source, first and second flow control valves fluidically coupled to Oxygen source and air source respectively. The inspiratory module further comprises first and second flow sensors fluidically coupled to Oxygen source and air source respectively. The inspiratory module further comprises a mixing chamber fluidically coupled to the Oxygen source and the air source and configured to mix a supply of Oxygen from the Oxygen source and a supply of air from the air source to generate Oxygen-air mixture. The inspiratory module further comprises an inspiratory line configured to supply the Oxygen-air mixture from the mixing chamber to a user. Furthermore, a pressure sensor configured to measure the gas pressure within the inspiratory line is also provided in the inspiratory module. The system further comprises an expiratory module configured in the ventilator and adapted to receive an exhaled gas from the user during the expiratory phase of ventilator cycle and vent out at least a portion of the exhaled gas to an exterior of the ventilator. The expiratory module comprises an exhalation membrane valve, a third flow control valve configured to be fluidically coupled to the inspiratory line and being configurable between at least a first state and a second state. In the first state, the third flow control valve allows flow of Oxygen-air mixture from the inspiratory line to the exhalation membrane valve. In the second state, the third flow control valve prevents the flow of Oxygen-air mixture from the inspiratory line to the exhalation membrane valve. The system further comprises a controller communicably coupled to the inspiratory module and the expiratory module. The controller comprises a processor and a memory communicably coupled to the processor. The memory stores instructions executable by the processor. The controller is configured to receive a set of two values of pressures for the ventilator. The first of the two values correspond to a maximum pressure of the gas inhaled by the user during inspiratory phase of ventilator cycle. The second of the two values correspond to a minimum allowable pressure of the gas inside the ventilator at an end of expiratory phase of ventilator cycle. The controller is further configured to, during the inspiratory phase of ventilator cycle, configure the third flow control valve in the first state and iteratively open the second and first flow control valves one after the other simultaneously, such that the pressure in the ventilator rises to the first value. The controller is further configured to, during the transition of the ventilator cycle from the inspiratory phase to an expiratory phase, switch the third flow control valve from the first state to the second state until the pressure drops from the first value to a third value, wherein the third value is greater than the second value. The controller is further configured to, during the expiratory phase of the ventilator cycle, switch the third flow control valve from the second state to the first state at a variable switching rate and iteratively open the second and first flow control valves one after the other simultaneously, such that the pressure in the ventilator drops from the third value to the second value.
In some embodiments, the controller is further configured to determine a corresponding user and ventilator parameters indicative of the inspiratory and expiratory time constants.
In some embodiments, the controller is further configured to maintain a predetermined fraction of Oxygen in the Oxygen-air mixture in the inspiratory line while simultaneously maintaining the pressure, by controlling supply of Oxygen from the Oxygen source and supply of air from the air source.
In some embodiments, the iterative opening of the second flow control valve, during inspiratory phase of ventilator cycle, is based on the first value of pressure and PID control feedback corresponding to the pressure in the ventilator as measured by the pressure sensor.
In some embodiments, the iterative opening of the second flow control valve, during expiratory phase of ventilator cycle, is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator as measured by the pressure sensor.
In some embodiments, the iterative opening of the first flow control valve is based on the predetermined fraction of Oxygen (FiO2), flow rate of the air from the air source as measured by the second flow sensor, and PID control feedback corresponding to the flow rate of the Oxygen from the Oxygen source as measured by the first flow sensor.
In some embodiments, the controller is further configured to switch the third flow control valve between the second state and the first state in two phases during the expiratory phase of the ventilator cycle. A first of the two phases is based on a first switching rate and a second of the two phases is based on a second switching rate. The second of the two phases occur after the first of the two phases, and the second switching rate is faster than the first switching rate.
In some embodiments, the rate of the variable switching of the third flow control valve is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator as measured by the pressure sensor.
In a second aspect, the present disclosure provides a method for regulating, during inspiratory phase of ventilator cycle, a first pressure of gas in a ventilator. The first pressure of gas corresponds to a maximum pressure of gas inhaled by a user during inspiratory phase of ventilator cycle. The method comprises configuring, by a controller, a third flow control valve configured to be fluidically coupled to an inspiratory line, in a first state. In the first state, the third flow control valve allows flow of Oxygen-air mixture from the inspiratory line to an exhalation membrane valve. The method further comprises iteratively opening, by the controller, second and first flow control valves fluidically coupled to air source and Oxygen source respectively, one after the other, such that the pressure in the ventilator as measured by a pressure sensor rises to the first pressure of gas. The iterative opening of the second flow control valve is based on the first pressure of gas and PID control feedback corresponding to a pressure in the ventilator as measured by the pressure sensor. Iterative opening the first flow control valve is based on a predetermined fraction of Oxygen (FiO2), flow rate of air from an air source as measured by a second flow sensor, and PID control feedback corresponding to a flow rate of Oxygen from an Oxygen source as measured by a first flow sensor.
In a third aspect, the present disclosure provides a method for regulating, during expiratory phase of ventilator cycle, a second pressure of gas in a ventilator. The second pressure of gas corresponds to a minimum allowable pressure of gas inside the ventilator at an end of expiratory phase of ventilator cycle. The method comprises configuring, by a controller, a third flow control valve configured to be fluidically coupled to an inspiratory line, in a second state until pressure in the ventilator as measured by a pressure sensor drops from a first value to a third value. In the second state, the third flow control valve prevents the flow of Oxygen-air mixture from the inspiratory line to an exhalation membrane valve. The first value corresponds to a maximum pressure of gas inhaled by a user during inspiratory phase of ventilator cycle. The third value is greater than the second pressure of gas. The method further comprises iteratively operating, by the controller, third flow control valve, and second and first flow control valves fluidically coupled to air source and Oxygen source respectively by:
Switching the third flow control valve from the second state to a first state at a variable switching rate. In the first state, the third flow control valve allows flow of Oxygen-air mixture from the inspiratory line to the exhalation membrane valve. The rate of the variable switching of the third flow control valve is based on the second value of pressure and PID control feedback corresponding to the pressure as measured by the pressure sensor.
Iteratively opening the second and a first flow control valves fluidically coupled to the air source and the Oxygen source respectively, one after the other, such that the pressure in the ventilator as measured by the pressure sensor drops from the third value to the second pressure of gas. The iterative opening of the second flow control valve is based on the second pressure of gas and PID control feedback corresponding to a pressure in the ventilator as measured by the pressure sensor. Iterative opening the first flow control valve is based on a predetermined fraction of Oxygen (FiO2), flow rate of air from the air source as measured by a second flow sensor, and PID control feedback corresponding to a flow rate of Oxygen from the Oxygen source as measured by a first flow sensor.
Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, explain the principles of the present disclosure.
Figure 1 illustrates a schematic diagram for a system 100 for regulating gas pressure in a ventilator 102, according to an embodiment of the present disclosure;
Figure 2 illustrates a schematic block diagram of a controller 200 of the system 100 of Figure 1, according to an embodiment of the present disclosure;
Figure 3 illustrates a graphical representation of gas pressure in the ventilator 102 with respect to time in the system 100 of Figure 1;
Figure 4 illustrates a schematic flow diagram of a method for regulating during inspiratory phase of ventilator cycle, a first pressure of gas in the ventilator 102, according to an embodiment of the present disclosure; and
Figure 5 illustrates a schematic flow diagram of a method for regulating during expiratory phase of ventilator cycle, a second pressure of gas in a ventilator 102, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized, and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings. The following detailed description is, therefore, not to be taken as limiting the scope of the invention.
As used herein, an element or step recited in the singular and proceeded with the word a or an should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to one embodiment of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments comprising or having an element or a plurality of elements having a particular property may include additional such elements not having that property.
The present subject matter discloses system and methods of regulating pressure and simultaneously maintaining fraction of Oxygen (FiO2) in a ventilator system during inspiratory and expiratory phases of ventilator cycle using cascaded closed loop feedback system. First part of the cascaded loop maintains the pressure level and the second part maintains the Oxygen level in the ventilator. In each iteration, the pressure sensor’s feedback is given to the air valve which increases the air flow and the output from the air flow sensor and Oxygen flow sensor is fed to the Oxygen flow valve which targets to achieve the Oxygen level in the system. The method is iterative throughout the breath cycle i.e. in the inspiratory phase and expiratory phase of the ventilator cycle to maintain PIP and PEEP respectively. During the first iteration, set pressure target is applied to the air valve and the feedback is through the pressure sensor. This generates a certain Pulse-width modulation (PWM) and system pressure rises to a certain level, during this time instance, the flow from air valve is measured and required Oxygen flow to maintain the Oxygen level is calculated which is then given as target to the Oxygen valve and the feedback is through the Oxygen flow sensor. This increases the flow from Oxygen valve which maintains the Oxygen level to set Oxygen level within the tolerance throughout the cycle. As the flow from the Oxygen valve increases, this leads to the increase of pressure to a certain level in the system as well, as a result the pressure error in the system is reduced. These iterations are performed till the system achieves the set pressure and set Oxygen level in both inspiratory phase and expiratory phase of the ventilator cycle.
Figure 1 illustrates a schematic diagram for a system 100 for regulating gas pressure in a ventilator 102, according to an embodiment of the present disclosure. The ventilator 102 may be any ventilator adapted to supply a ventilating gas to a user 190. The ventilator 102 includes an inspiratory module 104 adapted to supply a ventilating gas to the user 190 of the ventilator 102. The ventilating gas generally is a gas mixture including oxygen and air. The ventilator 102 is generally used to provide ventilating gas to users who are not able to breath without assistance. This may be due to various reasons which may cause pulmonary function to be depressed or compromised, such as disease, medical procedures, age, etc. The inspiratory module 104 may include various components, such as, without limitations, an Oxygen source 106, an air source 110, a mixing chamber 114. The mixing chamber 114 is configured to mix the supply of Oxygen and air from the Oxygen source 106 and the air source 110 respectively to generate Oxygen-air mixture. The air source 110 is compressed air.
The inspiratory module 104 may further include a pressure regulator 107 positioned between the Oxygen source 106 and the mixing chamber 114, that may regulate the pressure of the Oxygen being supplied by the Oxygen source 106. Furthermore, a pressure regulator 111 may be provided and positioned between the air source 110 and the mixing chamber 114, that may regulate the pressure of the air being supplied by the air source 110.
The inspiratory module 104 may further include a flow control proportional valve 108 positioned between the pressure regulator 107 and the mixing chamber 114. Further, the inspiratory module 104 may include a flow control proportional valve 112 positioned between the pressure regulator 111 and the mixing chamber 114. The flow control proportional valve 108 and the flow control proportional valve 112 are configured to regulate the flow of Oxygen and air respectively.
Furthermore, the inspiratory module 104 may include a flow sensor 109 positioned between the flow control proportional valve 108 and the mixing chamber 114. Further, the inspiratory module 104 may include a flow sensor 113 positioned between the flow control proportional valve 112 and the mixing chamber 114. The flow sensor 109 and the flow sensor 113 are configured to measure the flow of Oxygen and air respectively.
Furthermore, the inspiratory module 104 may include an inspiratory line 118 configured to supply the Oxygen-air mixture from the mixing chamber 114 to the user 190. A pressure sensor 115 may be provided and configured to measure the gas pressure within the inspiratory line 118. It should be noted that the pressure sensor 115 may be selected from any conventional pressure sensors already known in the art.
Additionally, in some embodiments, the inspiratory module 104 may further include a humidifier 116. As will be appreciated by those skilled in the art, the Oxygen-air mixture may cause dryness in the respiratory tract of the user 190 if supplied directly to the user 190 as is. Therefore, the Oxygen-air mixture may be passed through the humidifier 116 before it is supplied to the user 190. The humidifier 116 may add humidity to the air Oxygen-air mixture, to reduce the dryness effect which may be otherwise caused by the dry Oxygen-air mixture. The construction and working of the humidifier 116 may be same as is being used in those already known in the art. Thereafter, the Oxygen-air mixture upon humidification may be supplied to the user 190. It should be noted that the various fluidic couplings, i.e., the fluidic coupling between the Oxygen source 106 and the mixing chamber 114, the fluidic coupling between the air source 110 and the mixing chamber 114, etc. may be implemented via various associated tubes.
The ventilator 102 further includes an expiratory module 120 adapted to receive exhaled gas from the user 190 during the expiratory phase of ventilator cycle and vent out the exhaled gas out of the ventilator 102. In some embodiments, the exterior may be an ambient atmosphere. The expiratory module 120 may include various components, such as, without limitations, an exhalation membrane valve 122 and a flow control valve 121 fluidically coupled to the inspiratory line 118. The flow control valve 121 may be configurable between at least a first state and a second state. The flow control valve 121 may, in the first state allow flow of Oxygen-air mixture from the inspiratory line 118 to the exhalation membrane valve 122 which causes the exhalation membrane valve 122 to close, whereas the flow control valve 121 may, in the second state prevent the flow of Oxygen-air mixture from the inspiratory line 118 to the exhalation membrane valve 122 which causes the exhalation membrane valve 122 to open, thereby allowing exhaled gases (generated during the expiratory phase of breathing) to escape out of the ventilator 102. The exhalation membrane valve 122 may be configured to close during inspiratory phase due to pressure differential across the exhalation membrane valve 122. The exhalation membrane valve 122, in some example embodiments, may include an air pressure sensitive membrane, which depending on the pressure across it, may cause the open or close the flow of gas across the exhalation membrane valve 122. The expiratory module 120 may further include a flow sensor 123 adapted to measure the flow of exhaled gas from the user 190.
The flow control valve 121 may include multiple ports – a first port 121-1, a second port 121-2, and a third port 121-3. In some embodiments, the first port 121-1 may be fluidically coupled with the inspiratory line 118 to receive the Oxygen-air mixture therefrom. The second port 121-2 may be fluidically coupled with the exhalation membrane valve 122 of the expiratory module 120. The third port 121-3 may be configured to be open to the atmosphere. The first port 121-1, the second port 121-2, and the third port 121-3 may be selectively and individually opened and closed, for example based on a control signal. In an embodiment, the flow control valve 121 may be configured to proportionally distribute the Oxygen-air mixture received from the first port 121-1 between the second port 121-2 and the third port 121-3 based on a control signal. The proportional distribution of the Oxygen-air mixture helps in controlling the amount of Oxygen-air mixture supplied from the inspiratory line 118 to the exhalation membrane valve 122.
Therefore, in the first state, both the first port 121-1 and the second port 121-2 are open to thereby allow flow of the Oxygen-air mixture from the inspiratory line 118 to the exhalation membrane valve 122. It should be noted that the flow control valve 121 may be configured in the first state during inspiratory phase of ventilator cycle. It should be further noted that the flow control valve 121 may be configured to switch from the first state to the second state, in response to transition of the ventilator cycle from the inspiratory phase to an expiratory phase. In the second state, at least one of the first port 121-1 and the second port 121-2 may be closed to thereby prevent flow of the Oxygen-air mixture between the inspiratory line 118 and the exhalation membrane valve 122. In other words, in the second state, the flow of Oxygen-air mixture from the inspiratory line 118 to the exhalation membrane valve 122 is prevented. In an embodiment, in the second state, the flow control valve 121 may be configured to direct the flow of entire Oxygen-air mixture received at the first port 121-1 to the third port 121-3 and thereby prevent flow of the Oxygen-air mixture between the inspiratory line 118 and the exhalation membrane valve 122.
The inspiratory module 104 and the expiratory module 120 may be coupled to the user 190 and to each other through a Y-piece 117. The Y-piece 117 may include multiple ports, for example, a port coupled with the inspiratory line 118, a port coupled with the expiratory module 120, and another port coupled with a user 190 (a patient). The inspiratory line 118 may be therefore configured to supply the Oxygen-air mixture from the mixing chamber 114 to the user 190.
The ventilator 102 is communicably coupled to a controller 200 configured to operate the inspiratory module 104 and expiratory module 120 of the ventilator 102. The controller 200 is configured to regulate a gas pressure within the ventilator 102 while it is being used by the user 190.
Figure 2 illustrates a schematic block diagram of the controller 200 of the system 100, according to an embodiment of the present disclosure. Referring now to figure 1 and figure 2, the controller 200 includes the processor 202 communicably coupled with the memory 204. The memory 204 stores instructions (not shown) executable by the processor 202, such that the controller 200 is configured to regulate the gas pressure in the ventilator 102.
In some embodiments, the processor 202 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and/or any devices that process data based on operational instructions. Among other capabilities, the processor 202 may be configured to fetch and execute computer-readable instructions stored in the memory 204 for facilitating the system 100 to regulate gas pressure in the ventilator 102. Any reference to a task in the present disclosure may refer to an operation being or that may be performed on data. The memory 204 may be configured to store one or more computer-readable instructions or routines in a non-transitory computer readable storage medium for regulating the gas pressure in the ventilator 102. The memory 204 may include any non-transitory storage device including, for example, volatile memory such as RAM, or non-volatile memory such as EPROM, flash memory, and the like. In some embodiments, the controller 200 may include an interface 206. The interface 206 may include a variety of interfaces, for example, interfaces for data input and output devices, referred to as I/O devices, storage devices, and the like. The interface 206 may also provide a communication pathway for one or more components of the controller 200. Examples of such components may include but are not limited to a database 250.
In some embodiments, the controller 200 includes the processing engine 210. The processing engine 210 may be implemented as either programming instructions or a combination of hardware and programmable instructions to implement one or more functionalities of the processing engine 210. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing engine 210 may be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing engine 210 may include a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium (memory 204) may store instructions that, when executed by the processing resource 202, implement the processing engine 210.
The processing engine 210 includes a pressure values engine 212, a user and ventilator parameters engine 214, an inspiration operation engine 216, an expiratory operation engine 218, and other engine(s) 220. The other engine(s) 220 may include engines configured to perform one or more functions ancillary functions associated with the processing engine 210.
The pressure values engine 212 is configured to receive a set of values of pressure for the ventilator 102. The set of values of pressures may include first and second values. The first value may correspond to a maximum pressure of the gas inhaled in the ventilator 102 at an end of inspiratory phase of ventilator cycle. In some embodiments, the first value may be designated peak inspiratory pressure (PIP). The PIP may be a pressure required to force ventilating gas into lungs of the user 190. The second value may correspond to a minimum allowable pressure of the gas inside the ventilator 102 at an end of expiratory phase of ventilator cycle. In some embodiments, the second value may be designated positive end expiratory pressure (PEEP). The PEEP may be a minimum pressure to be maintained in the ventilator 102 so as to prevent collapse of the lungs of the user 190.
The user and ventilator parameters engine 214 is configured to determine user and ventilator parameters during operation of ventilator 102. The user and ventilator parameters are indicative of inspiratory and expiratory time constants of the user 190 and the ventilator 102.
The inspiration operation engine 216 is configured to, during the inspiratory phase of ventilator cycle, configure the flow control valve 121 in the first state and iteratively open the flow control valves 112 and 108 one after the other simultaneously, such that the pressure in the ventilator 102 as measured by the pressure sensor 115 rises to the first value. The iterative opening of the flow control valve 112 is based on the first value of pressure and proportional–integral–derivative (PID) control feedback corresponding to the pressure in the ventilator 102 as measured by the pressure sensor 115. The iterative opening of the flow control valve 112 maintains the required pressure level. The iterative opening of the flow control valve 108 is based on the predetermined fraction of Oxygen (FiO2), flow rate of air from the air source 110 as measured by the flow sensor 113, and PID control feedback corresponding to the flow rate of Oxygen from the Oxygen source 106 as measured by the flow sensor 109. The iterative opening of the flow control valve 108 maintains the Oxygen level in the inspiratory line 118, the required Oxygen flow is calculated by –
Required Oxygen flow= (air flow *(predetermined FiO2– 21)/(100 – predetermined FiO2))
The expiratory operation engine 218 is configured to, during the transition of the ventilator cycle from an inspiratory phase to an expiratory phase, switch the flow control valve 121 from the first state to the second state until the pressure in the ventilator 102 as measured by the pressure sensor 115 drops from a first value to a third value, where the third value is greater than the second value. The expiratory operation engine 218 is further configured to, during the expiratory phase of the ventilator cycle, switch the flow control valve 121 from the second state to the first state at a variable switching rate and iteratively open the flow control valves 112, 108 one after the other simultaneously, such that the pressure in the ventilator 102 as measured by the pressure sensor 115 drops from the third value to the second value. The rate of the variable switching of the flow control valve 121 is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator 102 as measured by the pressure sensor 115. The iterative opening of the flow control valve 112 is based on the second value of pressure and proportional–integral–derivative (PID) control feedback corresponding to the pressure in the ventilator 102 as measured by the pressure sensor 115. The iterative opening of the flow control valve 112 maintains the required pressure level. The iterative opening of the flow control valve 108 is based on the predetermined fraction of Oxygen (FiO2), flow rate of the air from the air source 110 as measured by the flow sensor 113, and PID control feedback corresponding to the flow rate of the Oxygen from the Oxygen source 106 as measured by the flow sensor 109. The iterative opening of the flow control valve 108 maintains the Oxygen level in the inspiratory line 118, the required Oxygen flow is calculated by –
Required Oxygen flow= (air flow *(predetermined FiO2– 21)/(100 – predetermined FiO2))
The switching the flow control valve 121 from the second state to the first state may be in response to pressure in the inspiratory line 118 falling below a predetermined pressure level. The variable switching between the second state and the first state in two phases. A first of the two phases (i.e., a first phase) may be based on a first switching rate. A second of the two phases (i.e., a second phase) may be based on a second switching rate. Further, the second phase may occur after the first phase. Furthermore, the second switching rate may be faster than the first switching rate. In other words, the rate of switching from the second state to the first state may vary such that the rate of switching may be slower initially (i.e., during the first phase) and the rate of switching may later become faster (i.e., during the second phase).
Figure 3 illustrates an exemplary plot 300 depicting a graphical representation 300 of the flow with respect to time in the ventilator 102 and the corresponding gas pressure in the ventilator 102 with respect to time is illustrated, in accordance with some embodiments of the present disclosure. The graph 300 depicts the pressure (along y-axis) with respect to time (along x-axis). The graphical representation 300 is obtained based on the operation of the flow control valves 112, 108 and 121.
As shown in Figure 3, the inspiratory phase of ventilator cycle extends from time t2 to time t3, during which the pressure in the ventilator 102 gradually rises, as per the curve between time t2 to time t3, in the graph 300. During the inspiratory phase of ventilator cycle, the flow control valve 121 is configured to operate in the first state. In the first state, the entire flow of the Oxygen-air mixture received at the port 121-1 of the valve 121 is directed towards the exhalation membrane valve 122 via port 121-2. This flow of the Oxygen-air mixture may cause the exhalation membrane valve 122 to close and thus prevent the flow of gases out of the ventilator 102. The controller 200, during the inspiratory phase, operate the flow control valves 112 and 108 in an iterative manner. During the first iteration, the first pressure value (PIP) is applied to the flow control valve 112 and the feedback is through the pressure sensor 115. The pressure in the inspiratory line 115 rises to a certain level, during this time instance, the required Oxygen flow to maintain the Oxygen level is calculated based on the output of the flow sensor 113 which is then given as target to the flow control valve 108 and the feedback is through the flow sensor 109. This increases the flow from flow control valve 108 to maintain the Oxygen level to predetermined FiO2. As the flow from the flow control valve 108 increases, the pressure in the inspiratory line 118 also increases to a certain, as a result the pressure error in the system is reduced. These iterations are performed till the system achieves the first pressure value (PIP) and predetermined FiO2 level.
Once the inspiration phase of ventilator cycle is over, at time t3, the expiration phase of ventilator cycle starts. At time t3, the flow control valve 121 may be configured to switch to the second state from the first state. In the second state, the entire flow of the Oxygen-air mixture received at the port 121-1 of the flow control valve 121 is directed towards port 121-3. This results in reduction in a pressure drop across the exhalation membrane valve 122 causing the exhalation membrane valve 122 to open. The opening of the exhalation membrane valve 122 causes the exhaled gases from the user 190 to freely escape from the ventilator 102 in the atmosphere resulting in a sudden drop in the pressure in the inspiratory line 118.
At point A (time tA), the pressure in the system may be just above the second value of pressure (PEEP). At this point, the controller 200 starts operating the flow control valves 112 and 108 iteratively such that the supply of the Oxygen-air mixture to the user 190 via the inspiratory line 118 may be started such that a desired FiO2% is maintained in the supplied Oxygen-air mixture.
At point B, when the pressure in the system has fallen below the second value of pressure (PEEP), the controller 200 switches the flow control valve 121 into the first state at a variable switching rate i.e. a certain proportion of the Oxygen-air mixture received at the port 121-1 is directed towards the exhalation membrane valve 122 via the port 121-2. The supply of Oxygen-air mixture causes the exhalation membrane valve 122 to gradually close. Once the exhalation membrane valve 122 starts closing, the dropping of pressure stops, and the pressure starts rising (as is depicted by the curve between time tB to time tD). As stated earlier, in the first state, the flow control valve 121 allows entire flow of Oxygen-air mixture from the inspiratory line 118 to the exhalation membrane valve 122. This supply of the Oxygen-air mixture from the inspiratory line 118 may cause the exhalation membrane valve 122 to close.
In some embodiments, the flow control valve 121 may be switched between the second state and the first state in two phases. In the first phase, the transition of the flow control valve 121 from the second state to the first state may take place at a first switching rate. The first phase may last from time tB to time tC.
At point C (time tC), the second phase of the transition of the flow control valve 121 from the second state to the first state may start. The second phase may take place at a second switching rate. The second phase may extend from time tC to time tD. As such, the second phase occurs after the first phases. In some embodiments, the second switching rate may be faster than the first switching rate. In other words, the switching of the flow control valve 121 from the second state to the first state may first take place via a slower transition (first phase, first switching rate) followed by a faster transition (second phase, second switching rate).
At point D (time tD), the switching of the flow control valve 121 from the second state to the first state may be complete. In the first state, the flow control valve 121 may therefore keep the exhalation membrane valve 122 closed, thereby preventing the drop of the pressure in the system. The pressure at time tD onwards is therefore maintained at the second value of pressure (PEEP). (It should be noted that the illustrated graph between point A and point D is merely for the purpose of explanation and the scale of the illustrated graph may not be in exact correspondence with actual use-case scenario graph.)
Figure 4 illustrates a schematic flow diagram of a method 400 for regulating during inspiratory phase of ventilator cycle, a first pressure of gas in a ventilator 102, according to an embodiment of the present disclosure. The first pressure of gas corresponds to a maximum pressure of gas inhaled by a user 190 during inspiratory phase of ventilator cycle. At step 402, the method 400 includes configuring, by the controller 200, a flow control valve 121 in a first state. In the first state, the flow control valve 121 allows flow of Oxygen-air mixture from an inspiratory line 118 to an exhalation membrane valve 122. At step 404, the method 400 further includes iteratively opening, by the controller 200, flow control valves 112 and 108 one after the other, such that the pressure in the ventilator 102 as measured by a pressure sensor 115 rises to the first pressure of gas. The iterative opening of the flow control valve 112 is based on the first pressure of gas and PID control feedback corresponding to a pressure in the ventilator 102 as measured by the pressure sensor 115. The iterative opening the flow control valve 108 is based on a predetermined fraction of Oxygen (FiO2), flow rate of air from the air source 110 as measured by a flow sensor 113, and PID control feedback corresponding to a flow rate of Oxygen from an Oxygen source 106 as measured by a flow sensor 109.
Figure 5 illustrates a schematic flow diagram of a method 500 for regulating during expiratory phase of ventilator cycle, a second pressure of gas in a ventilator 102, according to an embodiment of the present disclosure. The second pressure of gas corresponds to a minimum allowable pressure of gas inside the ventilator 102 at an end of expiratory phase of ventilator cycle. At step 502, the method 500 includes configuring, by the controller 200, a flow control valve 121 in a second state until pressure in the ventilator 102 as measured by a pressure sensor 115 drops from a first value to a third value. In the second state, the flow control valve 121 prevents flow of Oxygen-air mixture from an inspiratory line 118 to an exhalation membrane valve 122. The third value is greater than the second pressure of gas. The first value corresponds to a maximum pressure of gas inhaled by a user 190 during inspiratory phase of ventilator cycle. At step 504, the method 500 further includes iteratively operating, by the controller 200, flow control valve 121 and flow control valves 112 and 108 by –
Switching the flow control valve 121 from the second state to a first state at a variable switching rate. In the first state, the flow control valve 121 allows flow of Oxygen-air mixture from the inspiratory line 118 to the exhalation membrane valve 122. The rate of the variable switching of the flow control valve 121 is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator 102 as measured by the pressure sensor 115.
Iteratively opening the flow control valves 112 and 108 one after the other, such that the pressure in the ventilator 102 as measured by a pressure sensor 115 drops from the third value to the second pressure of gas. Iterative opening of the flow control valve 112 is based on the second pressure of gas and PID control feedback corresponding to the pressure as measured by the pressure sensor 115. Iterative opening the flow control valve 108 is based on a predetermined fraction of Oxygen (FiO2), flow rate of air from an air source 110 as measured by a flow sensor 113, and PID control feedback corresponding to a flow rate of Oxygen from an Oxygen source 106 as measured by a flow sensor 109.
It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF INVENTION
The present invention provides a system and method for regulating gas pressure in a ventilator during inspiratory and expiratory phases.
The present invention provides a system and method for regulating gas pressure in a ventilator while maintaining the required fraction of Oxygen (FiO2).
The present invention provides a system for effectively and accurately regulating gas pressures in a ventilator.
The present invention provides a system that can dynamically adapt to changes in a user’s lung parameters as well as to dynamics of the ventilator.
The present invention provides a system that limits discomfort to a user. , Claims:1. A system (100) for regulating gas pressure in a ventilator (102), the system (100) comprising:
an inspiratory module (104) configured in the ventilator (102), and adapted to supply a ventilating gas to a user (190) of the ventilator (102), the inspiratory module (104) comprising:
an Oxygen source (106);
an air source (110);
flow control valves (108, 112) fluidically coupled to the Oxygen source (106) and the air source (110) respectively;
flow sensors (109, 113) fluidically coupled to the Oxygen source (106) and the air source (110) respectively;
a mixing chamber (114) fluidically coupled to the Oxygen source (106) and the air source (110) and configured to mix a supply of Oxygen from the Oxygen source (106) and a supply of air from the air source (110), to generate Oxygen-air mixture;
an inspiratory line (118) configured to supply the Oxygen-air mixture from the mixing chamber (114) to the user (190); and
a pressure sensor (115) configured to measure the gas pressure within the inspiratory line (118);
an expiratory module (120) configured in the ventilator (102), and adapted to receive an exhaled gas from the user (190) during the expiratory phase of ventilator cycle, and vent out at least a portion of the exhaled gas to an exterior of the ventilator (102), the expiratory module (120) comprising:
an exhalation membrane valve (122); and
a flow control valve (121) configured to be fluidically coupled to the inspiratory line (118), the flow control valve (121) being configurable between at least a first state and a second state,
wherein in the first state, the flow control valve (121) allows flow of Oxygen-air mixture from the inspiratory line (118) to the exhalation membrane valve (122), and
wherein in the second state, the flow control valve (121) prevents the flow of Oxygen-air mixture from the inspiratory line (118) to the exhalation membrane valve (122); and
a controller (200) communicably coupled to the inspiratory module (104) and the expiratory module (120), the controller (200) comprising a processor (202) and a memory (204) communicably coupled to the processor (202), the memory (204) storing instructions executable by the processor (202), the controller (200) configured to:
receive a set of two values of pressures for the ventilator (102), wherein the first of the two values correspond to a maximum pressure of the gas inhaled by the user (190) during inspiratory phase of ventilator cycle, and the second of the two values correspond to a minimum allowable pressure of the gas inside the ventilator (102) at an end of expiratory phase of ventilator cycle;
during the inspiratory phase of ventilator cycle, configure the flow control valve (121) in the first state, and iteratively open the flow control valves (112, 108) one after the other simultaneously, such that the pressure in the ventilator (102) rises to the first value; and
during the transition of ventilator cycle from the inspiratory phase to an expiratory phase, switch the flow control valve (121) from the first state to the second state until the pressure in the ventilator (102) as measured by the pressure sensor (115) drops from a first value to a third value, wherein the third value is greater than the second value, and
during the expiratory phase of the ventilator cycle, switch the flow control valve (121) from the second state to the first state at a variable switching rate and iteratively open the flow control valves (112, 108) one after the other simultaneously, such that the pressure in the ventilator (102) as measured by the pressure sensor (115) drops from the third value to the second value.

2. The system (100) as claimed in claim 1, wherein the controller (200) is further configured to determine a corresponding user and ventilator parameters indicative of the inspiratory and expiratory time constants.

3. The system (100) as claimed in claim 1 or 2, wherein the controller (200) is further configured to maintain a predetermined fraction of Oxygen (FiO2) in the Oxygen-air mixture in the inspiratory line (118) while simultaneously maintaining the pressure in the ventilator (102) as measured by the pressure sensor (115), by controlling supply of Oxygen from the Oxygen source (106) and supply of air from the air source (110).

4. The system (100) as claimed in claim 3, wherein the iterative opening of the flow control valve (112), during inspiratory phase of ventilator cycle, is based on the first value of pressure and PID control feedback corresponding to the pressure in the ventilator (102) as measured by the pressure sensor (115).

5. The system (100) as claimed in claim 3, wherein the iterative opening of the flow control valve (112), during expiratory phase of ventilator cycle, is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator (102) as measured by the pressure sensor (115).

6. The system (100) as claimed in claim 5, wherein the iterative opening of the flow control valve (108) is based on the predetermined fraction of Oxygen (FiO2), flow rate of the air from the air source (110) as measured by the flow sensor (113), and PID control feedback corresponding to the flow rate of the Oxygen from the Oxygen source (106) as measured by the flow sensor (109).

7. The system (100) as claimed in claim 6, wherein the controller (200) is further configured to switch the flow control valve (121) between the second state and the first state in two phases during the expiratory phase of the ventilator cycle,
wherein a first of the two phases is based on a first switching rate and a second of the two phases is based on a second switching rate,
wherein the second of the two phases occurs after the first of the two phases, and
wherein the second switching rate is faster than the first switching rate.

8. The system (100) as claimed in claim 6 or 7, wherein the rate of the variable switching of the flow control valve (121) is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator (102) as measured by the pressure sensor (115).

9. A method (400) for regulating, during inspiratory phase of ventilator cycle, a first pressure of gas in a ventilator (102), wherein the first pressure of gas corresponds to a maximum pressure of gas inhaled by a user (190) during inspiratory phase of ventilator cycle, the method (400) comprising:
configuring (402), by a controller (200), a flow control valve (121) in a first state, wherein in the first state, the flow control valve (121) allows flow of Oxygen-air mixture from an inspiratory line (118) to an exhalation membrane valve (122); and
iteratively opening (404), by the controller (200), flow control valves (112, 108) one after the other, such that the pressure in the ventilator (102) as measured by a pressure sensor (115) rises to the first pressure of gas,
wherein the iterative opening of the flow control valve (112) is based on the first pressure of gas and PID control feedback corresponding to a pressure in the ventilator (102) as measured by the pressure sensor (115), and
wherein the iterative opening the flow control valve (108) is based on a predetermined fraction of Oxygen (FiO2), flow rate of air from an air source (110) as measured by a flow sensor (113), and PID control feedback corresponding to a flow rate of Oxygen from an Oxygen source (106) as measured by a flow sensor (109).

10. A method (500) for regulating, during expiratory phase of ventilator cycle, a second pressure of gas in a ventilator (102), wherein the second pressure of gas corresponds to a minimum allowable pressure of gas inside the ventilator (102) at an end of expiratory phase of ventilator cycle, the method (500) comprising:
configuring (502), by a controller (200), a flow control valve (121) in a second state until pressure in the ventilator (102) as measured by a pressure sensor (115) drops from a first value to a third value,
wherein in the second state, the flow control valve (121) prevents flow of Oxygen-air mixture from an inspiratory line (118) to an exhalation membrane valve (122),
wherein the third value is greater than the second pressure of gas, and
wherein the first value corresponds to a maximum pressure of gas inhaled by a user (190) during inspiratory phase of ventilator cycle;
iteratively operating (504) by the controller (200), flow control valve (121) and flow control valves (112, 108) by:
switching the flow control valve (121) from the second state to a first state at a variable switching rate, wherein in the first state, the flow control valve (121) allows flow of Oxygen-air mixture from the inspiratory line (118) to the exhalation membrane valve (122),
wherein the rate of the variable switching of the flow control valve (121) is based on the second value of pressure and PID control feedback corresponding to the pressure in the ventilator (102) as measured by the pressure sensor (115); and
iteratively opening the flow control valves (112, 108) one after the other, such that the pressure in the ventilator (102) as measured by the pressure sensor (115) drops from the third value to the second pressure of gas,
wherein iterative opening of the flow control valve (112) is based on the second pressure of gas and PID control feedback corresponding to a pressure in the ventilator (102) as measured by the pressure sensor (115), and
wherein iterative opening the flow control valve (108) is based on a predetermined fraction of Oxygen (FiO2), flow rate of air from an air source (110) as measured by a flow sensor (113), and PID control feedback corresponding to a flow rate of Oxygen from an Oxygen source (106) as measured by a flow sensor (109).

11. The method (500) as claimed in claim 10, wherein the variable switching of the flow control valve (121) between the second state and the first state occur in two phases,
wherein a first of the two phases is based on a first switching rate and a second of the two phases is based on a second switching rate,
wherein the second of the two phases occur after the first of the two phases, and
wherein the second switching rate is faster than the first switching rate.