DESC:FIELD OF TECHNOLOGY
The present disclosure relates to pressure-controlled ventilation techniques, and more particularly, to a system and method to deliver a desired quantity of fraction of inspired oxygen (FiO2) to a patient.

BACKGROUND
Ventilation systems are used in medical field to provide breathing support and assistance to patients having breathing and respiratory disorders. Nowadays, mechanical ventilators are most commonly integrated with computer technologies to meet individual requirements in providing breathing assistance to patients. The most common types of mechanical ventilation system are volume-controlled and pressure controlled. The pressure-controlled ventilation system delivers air and/or oxygen till a target airway pressure limit is reached. For pressure controlled ventilation, the volume of air delivered to airways and/or lungs may vary based on the airway resistance and lung capacity.

In the conventional art, the pressure-controlled ventilator system usually delivers a mixture of air and oxygen to the patient, wherein the percentage of oxygen in the mixture is referred as fraction of inspired oxygen (FiO2). The value of FiO2 in an air mixture may vary from 21% to 100%. The target FiO2 that needs to be delivered to a patient depends on the criticality of the patient, as more oxygen would be required for severely critical patient. Particularly in conventional ventilation systems, the target FiO2 is achievable only in multiple breathing cycles, i.e., it may take a long time to meet the target FiO2. This may be disadvantageous to patients’ health, in cases of extreme emergency because of the delay in providing desired concentration of oxygen at the right time.

Furthermore, patient circuits or the tube assembly connected to a patient, may vary depending on different patient categories such as neonatal, pediatric and adults. This is because tube diameter and tube length can influence, the flow rate, volume, pressure and other similar factors. Furthermore, different patients have different lung compliance factor, thus the ventilator usually provides different settings and modes, to adapt to a patients’ needs. These settings are either adjusted manually by the doctor or are dependent on the doctor’s inputs/instructions to the ventilator.

Therefore, in light of the above, there exists a long felt need to overcome the aforementioned challenges associated with existing ventilation techniques.

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 disclosure.

It is to be understood that the aspects and embodiments of the disclosure described below may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

In one non-limiting embodiment, the present disclosure provides a pressure-controlled ventilation method for delivery of oxygen to a patient. The method comprises providing an air chamber and an oxygen chamber both connected to a mixing chamber in such a manner that the air chamber is connected to the mixing chamber via a first proportional valve and a first flow sensor and the oxygen chamber is connected to the mixing chamber via a second proportional valve and a second flow sensor. The method further comprises monitoring an air flow rate of air and an oxygen flow rate of the oxygen while the air and the oxygen are flowing from the air chamber and the oxygen chamber respectively to the mixing chamber. Then a current air partial pressure and a current oxygen partial pressure is computed based on the air flow rate and the oxygen flow rate and a current total pressure in the mixing chamber. The method further comprises computing a desired air partial pressure and a desired oxygen partial pressure from a total target pressure and a target oxygen level. The method further comprises generating a first control signal based on deviation of the current air partial pressure from the desired air partial pressure, and generating a second control signal based on deviation of the current oxygen partial pressure from the desired oxygen partial pressure. The first proportional valve and the second proportional valve are adjusted based on the first control signal and on the second control signal respectively such that the mixing chamber generates an air mixture by mixing the air and the oxygen received from the air chamber and the oxygen chamber respectively. The air mixture is delivered via an inspiration tube to the patient, where the inspiration tube connects to the mixing chamber and wherein a concentration of the oxygen in the air mixture meets the target oxygen level.

In another non-limiting embodiment, the present disclosure provides a pressure-controlled ventilation system for delivery of oxygen to a patient. The system comprises an air chamber and an oxygen chamber both connected to a mixing chamber in such a manner that the air chamber is connected to the mixing chamber via a first proportional valve and a first flow sensor and the oxygen chamber is connected to the mixing chamber via a second proportional valve and a second flow sensor. Further, the system comprises a microcontroller unit configured to monitor an air flow rate of air and an oxygen flow rate of the oxygen while the air and the oxygen are flowing from the air chamber and the oxygen chamber respectively to the mixing chamber. The micro controller unit computes a current air partial pressure and a current oxygen partial pressure based on the air flow rate and the oxygen flow rate and a current total pressure in the mixing chamber. The microcontroller unit computes a desired air partial pressure and a desired oxygen partial pressure from a total target pressure and a target oxygen level. The micro controller unit is further configured to generate a first control signal based on deviation of the current air partial pressure from the desired air partial pressure. The microcontroller unit generates a second control signal based on deviation of the current oxygen partial pressure from the desired oxygen partial pressure. The microcontroller unit adjusts the first proportional valve and the second proportional valve based on the first control signal and the second control signal respectively such that the mixing chamber generates an air mixture by mixing the air and the oxygen received from the air chamber and the oxygen chamber. The system comprises an inspiration tube connected to the mixing chamber delivers the air mixture to the patient, wherein a concentration of the oxygen in the air mixture meets the target oxygen level.

In another embodiment, the air flow rate and the oxygen flow rate are detected by the first flow sensor and the second flow sensor respectively.

In another embodiment, the current total pressure is determined by a pressure sensor connected to the mixing chamber.

In another embodiment, the total target pressure is a sum of a target Peak Inspiratory Pressure (PIP) and a target Positive end-expiratory pressure (PEEP) and wherein the total target pressure varies based on the patient.

In another embodiment, the target oxygen level is a fraction of inspired oxygen (FiO2) in the air mixture.

The present disclosure is able to achieve desired FiO2 percentage for ventilated patients from a first breathing cycle of the ventilation system.

The present disclosure provides an efficient pressure-controlled ventilation system for faster delivery of target FiO2 to the patients. The present disclosure provides a control loop mechanism to achieve accurate concentration of FiO2 at the right time.

The present disclosure is adaptable to the changing needs of patients having respiratory and breathing disorders thereby requiring minimum effort on part of the doctor or respiratory therapists.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure Error! Reference source not found. illustrates a block diagram of a pressure-controlled ventilation system 100 that delivers desired quantity of oxygen to a patient, in accordance with aspects of the present disclosure.

Figure 2 illustrates exemplary block diagram of a pressure-controlled ventilation system 200 that delivers desired quantity of oxygen to a patient, in accordance with aspects of the present disclosure.

Figure 3 illustrates a flowchart of a pressure-controlled ventilation method 300 that delivers desired oxygen to patient, in accordance with aspects of the present disclosure.

It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION
In the present document, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or implementation of the present subject matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

The terms like “multiple” and “plurality” may be used interchangeably throughout the description. The terms like “ventilator device” and “ventilation system”, may be used interchangeably throughout the description.

In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration of specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.

Those skilled in the art, are aware that a pressure-controlled ventilation, (PCV) is a mechanical ventilation technique wherein two pressure levels are maintained during a breathing cycle. A breathing cycle of a ventilation system primarily includes two distinct phases. The first phase is called inspiration or inhalation. During inhalation, the pressure inside the lungs decreases, thereby causing air to rush in and fill the lungs. The second phase is called expiration or exhalation. During exhalation, the pressure within the lungs increases, thereby causing the lungs to contract and force the air out. During the breathing cycle air is pushed into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe or requires assistance. Ventilators may comprises of variety of features such as controlled volume delivery, controlled respiratory rate, patient trigger, pressure support, volume support, etc.

The two pressure levels maintained in PCV include a lower pressure level also known as Positive end-expiratory pressure (PEEP), and a higher-pressure level which is also known as peak inspiratory pressure (PIP). PEEP is the positive pressure that remains in the airways and/or lungs of the patient at the end of the breathing cycle, i.e., at the end of exhalation. PIP is the highest level of pressure applied to the lungs during inhalation. In mechanical ventilation a positive pressure is usually measured in centimeters of water pressure (cmH2O). A pressure-controlled ventilator system controls these two pressure levels for every breathing cycle of the patient, in addition to maintaining other ventilator settings. These ventilator settings may be inputted into the ventilator system by the doctor based on the patient’s needs. The ventilator settings may correspond to tidal volume, respiratory rate and Fraction of Inspired Oxygen (FiO2). FiO2 is the amount of oxygen required during the breathing cycle.

Ventilators also comprises distinct respiratory lines known as inspiratory line and expiratory line. The inspiratory line pushes air into the lungs of the patients. The inspiratory line may be invasive in nature, i.e., its passes through the nasal cavity or throat of the patient to provide air to the lungs of the patient.

Ventilators are complex devices that need to be administered by highly trained professionals. Typically, the trained professionals provide input to the ventilator devices by manually adjusting the ventilator settings. As known in the art, in conventional ventilators, a healthcare professional constantly monitors a ventilator setting such as an FiO2 level. In case, there is a requirement for adjusting the FiO2 level, the healthcare professional in turn adjusts the oxygen coming from an oxygen chamber via a mechanical knob. The mechanical knob is coupled to a mechanical valve to allow the flow of oxygen from the oxygen cylinder to the patient.

However, due to a manual procedure, the desired FiO2 level required by the patient is achieved after several breathing cycles. In case, the patient is in a critical state, the conventional ventilation system may be disadvantageous to the health of the patient because of the delay in achieving the required oxygen level. The present disclosure provides pressure-controlled ventilation system and method that provides desired quantity of oxygen to a patient from a first breathing cycle.

Referring to Figure 1, the present disclosure provides a pressure-controlled ventilation system 100 that provides efficient and fast delivery of desired quantity of oxygen to patients with breathing or respiratory disorders. An air chamber 102 is provided to store a pre-determined quantity of air with a pre-set pressure. Usually atmospheric air contains 21% of oxygen. Further, an oxygen chamber 126 is provided to deliver a desired concentration of oxygen to the patients. The air and oxygen are intermixed in a mixing chamber 114 to obtain a gas mixture. The objective of the disclosure is to achieve the target FiO2 level in the gas mixture. The gas mixture is then supplied to the patient, through an inspiration tube 118.

The system further comprises a first proportional valve 106 and a second proportional valve 122. The proportional valves are control valve that will open and close the respective air and oxygen chambers based on one or more control signals.

The system also comprises a first pressure regulator 104 and a second pressure regulator 124, connected to the air chamber 102 and oxygen chamber 126 respectively. The pressure regulators aid in maintaining a required quantity of pressure in the respective air chamber 102 and oxygen chamber 126. The required quantity of pressure may be pre-set in the ventilator or may be received as an input from an operator.

In another embodiment, the air chamber 102 may be connected with a blower configured to extract ambient air from surroundings and deliver it to the mixing chamber 114. The blower is configured to compress the air to a pre-determined pressure. The air chamber 102 may also comprise one or more filters to filter and purify the air in the air chamber 102.

In another embodiment, the system comprises a first flow sensor 108 and a second flow sensor 120 arranged such that to detect flow-rates of the respective gases flowing into the mixing chamber 114. The first flow sensor 108 detects an air flow rates of the air flowing from the air chamber 102 to the mixing chamber 114. The second flow sensor 120 detects an oxygen flow rate of the oxygen flowing from the oxygen chamber 126 to the mixing chamber 114. Within the scope of the present disclosure, the ventilator system 100 discloses comprise two flow paths, namely, an air path and an oxygen path . In accordance with the present disclosure, the air path traverses the flow of air from the air chamber 102 to the mixing chamber 114 and the oxygen path traverses the flow of oxygen from the oxygen chamber 126 to the mixing chamber 114. The mixing chamber is adapted to be coupled to the air chamber 102 and the oxygen chamber 126 such that the air path and the oxygen path merge with each other at the mixing chamber 114 to provide a desired quantity of air-oxygen mixture to the patient.

The mixing chamber 114 deliver the gas mixture to the patient, via an inspiration tube 118. The system 100 further comprises a pressure sensor 116 configured to measure a run-time pressure value of the gas mixture contained in the mixing chamber 114.

The system comprises a microcontroller unit 112 configured to monitor the air flow rate and the oxygen flow rate. Further, the microcontroller 112 is configured to compute a current air partial pressure and a current oxygen partial pressure based on the air flow rate and the oxygen flow rate and the run-time pressure value. It is known in the art that a flow rate can be deduced as the volume of gas at a particular instant of time. The current air partial pressure and a current oxygen partial pressure are computed by integrating the air flow rate and oxygen flow rate in a unit of time, respectively.

The run-time pressure value referred here as P_T is used in the computation. The pressure sensor 116 detects pressure of the gas mixture present in the mixing chamber 114. The moles of air or oxygen, i.e., moles_air and moles_o2 at a particular instant of time are calculated based on the following equation:
moles_(air or o2)=(?(Flow rate?_(air or o2)×dt)×(mass_density of air or o2) )/((molecular mass of air or o2))
Here, the mass_density of air and oxygen; and the molecular mass of air and oxygen are constants known in the art. Accordingly, partial pressures are calculated based on the the following equation:
P_air= ?moles?_air/(?moles?_air+ ?moles?_o2 ) ×P_total
P_o2= ?moles?_o2/(?moles?_air+ ?moles?_o2 ) ×P_total
The microcontroller unit 112 is configured to compute a desired air partial pressure and a desired oxygen partial pressure from a total target pressure and a target oxygen level. The total target pressure to be achieved is, is determined as follows:
P_total= ?PIP?_ + ?PEEP?_

The total target pressure is a sum of target PIP and target PEEP.

Therefore, the required partial pressures of both the air and oxygen can be calculated using following equations:
P_(air req.)=(( (100-set_fio2 )* (PIP+PEEP))/79)
P_(O2 req.)=P_(total )-P_(air req.)

The above desired partial pressure of oxygen is computed based on the understanding that pressures of two gases can be added up to form a combined pressure of the air mixture.
P_total= P_air+ P_O2
where P_air=Partial pressure of air in the mixture,
P_O2=Partial pressure of Oxygen in the mixture
where set_fio2 is the target FiO2 that needs to be achieved by the ventilation system.
The P_(air req.) is desired air partial pressure and P_(O2 req.)desired oxygen partial pressure. The difference between P_(air req.) and P_air is known as the error value e_air (t). This error value is then used in adjusting the first proportional valve 106 of air chamber 102. Similarly, the difference between P_(O2 req.) and P_o2 is known as the error value e_O2 (t), which is utilized in adjusting the second proportional valve 122 of oxygen chamber 126.

The present disclosure thus utilizes the instantaneous flow rate to determine whether the run-time partial pressures of the air and oxygen meet the target partial pressures and aims to achieve the desired oxygen concentration as well as maintain the target pressure parameters (PIP and PEEP) in the patients’ airway.

In another embodiment, the doctor or trained professional operating the ventilator system 100 may input the target peak inspiratory pressure (PIP) value and the target positive end-expiratory pressure (PEEP) value via the ventilator interface 110.

In another embodiment, microcontroller unit 112 generates control signals such as a first control signal and a second control signal based on the error values computed. The control signals may be in digital form. Pulse width modulation (PWM) is performed on the signals generated from the microcontroller unit 112 for conversion into analog signals. These analog signals are then applied to the proportional valves, i.e. a first proportional valve 106 and a second proportional valve 122.

In another embodiment, the microcontroller unit may comprise a proportional integral derivative (PID) controller 202 that operates on the error values of the instantaneous partial pressures. The PID controller 202 combines proportional control with additional integral and derivative adjustments and compensates for the. The PID controller in the present disclosure adjusts or tunes the error values to achieve the target oxygen level. The PID controller 202 works in a control loop mechanism by iteratively adjusting the error values through proportional, integral and derivative computations to adjust an output signal such as ug (??). The following equations are used in the PID controller 202. The PID Controller 202 is similar in function to the PID controller 202’.

Proportional (P) control Equation 1: ??? * ??g (??) adjusts the output ug (??) based on the current error ??g (??).

Integral (I) control Equation 2: ???? * (??(??g (??)))/???? adjusts the output ug (??) based on the accumulated error ??g (??) over time.

Derivative (D) control Equation 3: ????*?( ??g (??)???? based on the rate of change of the error ??g (??)

??? , ???? , and ???? are constants and ??g is the error value of the gases i.e., air or oxygen.

In another embodiment, the output signal ug (??) may be adjusted to obtain the control signal provided to the respective proportional valves. The first pressure regulator 104 may be adapted to regulate pressure of the air in the air chamber 102 based on a user input or patient’s feedback. The second pressure regulator 124 may be adapted to regulate pressure of the oxygen in the oxygen chamber 126 based on a user input or patient’s feedback. In one embodiment, the user input is received through an input device for example a display unit In an embodiment, the patient’s feedback may be detected by a plurality of sensors for example, a Oxygen saturation (SPO2) sensor or oximeter attached to the patient. SpO2 sensor measures how much oxygen patient’s blood is carrying as a percentage of the maximum it could carry.

In an embodiment, the target parameters: PIP, PEEP and FiO2 are received as inputs using the ventilator interface. Further these parameters can be easily changed, as required by the respiratory therapist or doctor. In another embodiment, the mixing chamber 114 connects to an inspiration tube 118 that provides the path of flow of air mixture with the required quantity of oxygen to the patient. The inspiration tube forms part of the inhalation side of a breathing circuit of the ventilation system. In another embodiment, the ventilation system 100 may also comprise one of an endotracheal (ET) tube, ventilator face mask, or nasal mask connected to the inspiration tube 118 as a part of the patient breathing assembly.

Furthermore, the feature of dynamic computation of partial pressures of the gases and run-time adjustment of oxygen concentration, makes the present mechanism suitable for different categories of patients such as infant, neonatal, pediatric and adult.

Further, the present disclosure is not limited to an isothermal state of the ventilation system. The performance of the present system remains unaffected by the changes in temperature that in turn affects the density of the gases. The process for computing the pressure variable for the oxygen gas and air nullifies or cancels the variations in the density of the gases, in case of temperature variations. Following is the theoretical analysis of the same. It is known in the art that ideal gas equation gives us the relation of density (?) with total gas pressure (P) and temperature (T).

P/?=(R ×T)/M
The molar mass (M) and ideal gas constant (R) are constant for a particular gas i.e., air or oxygen. Thus, the equation is further expressed as:
?=k × P/T
k=M/R
Further, moles (n) inducted inside the lung per unit time is expressed in terms of volume flow rate (Q) as
n=(Q × ?)/M
Further moles of air (n_air) and O2 (n_O2) and mole fractions (?x_air,x?_O2) are subsequently computed as following based on the above relations. P is the total pressure of a gas mixture (air and oxygen).
n_air=(Q_air×?_air)/M_air =Q_air×P/T×1/R
n_O2=(Q_O2×?_O2)/M_O2 =Q_O2×P/T×1/R
x_air=n_air/(n_air+ n_O2 )=Q_air/(Q_air+Q_O2 )×((P/(R×T)))/((P/(R×T)) )=Q_air/(Q_air+Q_O2 )
x_O2=n_O2/(n_air+ n_O2 )=Q_O2/(Q_air+Q_O2 )×((P/(R×T)))/((P/(R×T)) )=Q_O2/(Q_air+Q_O2 )
Thus, density change due to change in pressure has no effect in the final moles calculation.

Referring to Figure 3, a method 300 of pressure-controlled ventilation for delivery of oxygen to a patient. In block 302 the method includes providing an air chamber 102 and an oxygen chamber 126 both connected to a mixing chamber 114 in such a manner that the air chamber 102 is connected to the mixing chamber 114 via a first proportional valve 106 and a first flow sensor 108 and the oxygen chamber 126 is connected to the mixing chamber 114 via a second proportional valve 122 and a second flow sensor 120.

At block 304, the method includes monitoring an air flow rate of air and an oxygen flow rate of the oxygen while the air and the oxygen are flowing from the air chamber 102 and the oxygen chamber 126 respectively to the mixing chamber 114.

At block 306, the method includes computing a current air partial pressure and a current oxygen partial pressure based on the air flow rate and the oxygen flow rate and a current total pressure in the mixing chamber 114.

Further at block 308, the method includes computing a desired air partial pressure and a desired oxygen partial pressure from a total target pressure and a target oxygen level. In another embodiment, the total target pressure is a sum of a target Peak Inspiratory Pressure (PIP) and a target Positive end-expiratory pressure (PEEP) and wherein the total target pressure varies based on the patient.

At block 310, the method includes generating a first control signal based on deviation of the current air partial pressure from the desired air partial pressure. At block 312, the method includes generating a second control signal based on deviation of the current oxygen partial pressure from the desired oxygen partial pressure. In another embodiment, the target oxygen level is a fraction of inspired oxygen (FiO2) in the air mixture.

At block 314, the method includes adjusting the first proportional valve 106 and the second proportional valve 122 based on the first control signal and on the second control signal respectively such that the mixing chamber 114 generates an air mixture by mixing the air and the oxygen received from the air chamber 102 and the oxygen chamber 126 respectively.

At block 316, the method includes delivering the air mixture via an inspiration tube 118 to the patient, wherein the inspiration tube 118 connects to the mixing chamber 114 and wherein a concentration of the oxygen in the air mixture meets the target oxygen level.

The various blocks of the method 300 shown in Figure 3 have been arranged in a generally sequential manner for ease of explanation. However, it is to be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with the method 300 (and the blocks shown in Figure 3) can occur in a different order (for example, where at least some of the processing associated with the blocks is performed in parallel and/or in an event-driven manner). Additionally, individual blocks may be deleted from the methods without departing from the spirit and scope of the subject matter described herein. Furthermore, the methods can be implemented in any suitable hardware, software, firmware, or combination thereof.

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s). Generally, where there are operations illustrated in Figures, those operations may have corresponding counterpart means-plus-function components.

In a non-limiting embodiment of the present disclosure, one or more non-transitory computer-readable media may be utilized for implementing the embodiments consistent with the present disclosure. A computer-readable media refers to any type of physical memory on which information or data readable by a processor may be stored. Certain non-limiting embodiments may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer readable media having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain non-limiting embodiments, the computer program product may include packaging material.

As used herein, a phrase referring to “at least one” or “one or more” of a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c. The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise.

A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the disclosed methods and systems.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the disclosure be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present disclosure are intended to be illustrative, but not limiting, of the scope of the disclosure, which is set forth in the appended claims

Reference Numerals used
Air Chamber 102
First Pressure Regulator 104
First Proportional Valve 106
First Flow Sensor 108
Ventilator Interface 110
Microcontroller Unit 112
Mixing Chamber 114
Pressure Sensor 116
Inspiration Tube 118
Second Flow Sensor 120
Second Proportional Valve 122
Second Pressure Regulator 124
Oxygen Chamber 126 ,CLAIMS:We Claim:

1. A pressure-controlled ventilation method for delivery of oxygen to a patient, the method comprising:
providing an air chamber (102) and an oxygen chamber (126) both connected to a mixing chamber (114) in such a manner that the air chamber (102) is connected to the mixing chamber (114) via a first proportional valve (106) and a first flow sensor (108) and the oxygen chamber (126) is connected to the mixing chamber via a second proportional valve (122) and a second flow sensor (120);
monitoring an air flow rate of air and an oxygen flow rate of the oxygen while the air and the oxygen are flowing from the air chamber (102) and the oxygen chamber (126) respectively to the mixing chamber (114);
computing a current air partial pressure and a current oxygen partial pressure based on the air flow rate and the oxygen flow rate and a current total pressure in the mixing chamber (114);
computing a desired air partial pressure and a desired oxygen partial pressure from a total target pressure and a target oxygen level;
generating a first control signal based on deviation of the current air partial pressure from the desired air partial pressure;
generating a second control signal based on deviation of the current oxygen partial pressure from the desired oxygen partial pressure;
adjusting the first proportional valve (106) and the second proportional valve (122) based on the first control signal and on the second control signal respectively such that the mixing chamber (114) generates an air mixture by mixing the air and the oxygen received from the air chamber (102) and the oxygen chamber (126) respectively; and
delivering the air mixture via an inspiration tube to the patient, wherein the inspiration tube connects to the mixing chamber (114) and wherein a concentration of the oxygen in the air mixture meets the target oxygen level.

2. The method as claimed in claim 1, wherein the air flow rate and the oxygen flow rate are detected by the first flow sensor (108) and the second flow sensor (120) respectively.

3. The method as claimed in claim 1, wherein the current total pressure is determined by a pressure sensor connected to the mixing chamber (114).

4. The method as claimed in claim 1, wherein the total target pressure is a sum of a target Peak Inspiratory Pressure (PIP) and a target Positive end-expiratory pressure (PEEP) and wherein the total target pressure varies based on the patient.

5. The method as claimed in claim 1, wherein the target oxygen level is a fraction of inspired oxygen (FiO2) in the air mixture.

6. A pressure-controlled ventilation system for delivery of oxygen to a patient comprising an air chamber (102) and an oxygen chamber (126) both connected to a mixing chamber (114) in such a manner that the air chamber (102) is connected to the mixing chamber (114) via a first proportional valve (106) and a first flow sensor (108) and the oxygen chamber (126) is connected to the mixing chamber (114) via a second proportional valve (122) and a second flow sensor (120), the system comprises:
a microcontroller unit (112) configured to:
monitor an air flow rate of air and an oxygen flow rate of the oxygen while the air and the oxygen are flowing from the air chamber (102) and the oxygen chamber (126) respectively to the mixing chamber (114);
compute a current air partial pressure and a current oxygen partial pressure based on the air flow rate and the oxygen flow rate and a current total pressure in the mixing chamber (114);
compute a desired air partial pressure and a desired oxygen partial pressure from a total target pressure and a target oxygen level;
generate a first control signal based on deviation of the current air partial pressure from the desired air partial pressure;
generate a second control signal based on deviation of the current oxygen partial pressure from the desired oxygen partial pressure; and
adjust the first proportional valve (106) and the second proportional valve (122) based on the first control signal and the second control signal respectively such that the mixing chamber (114) generates an air mixture by mixing the air and the oxygen received from the air chamber (102) and the oxygen chamber (126); and
an inspiration tube connected to the mixing chamber (114) delivers the air mixture to the patient, wherein a concentration of the oxygen in the air mixture meets the target oxygen level.

7. The system as claimed in claim 6, wherein the air flow rate and the oxygen flow rate are detected by the first flow sensor (108) and the second flow sensor (120) respectively.

8. The system as claimed in claim 6, wherein the current total pressure is determined by a pressure sensor connected to the mixing chamber (114).

9. The system as claimed in claim 6, wherein the total target pressure is a sum of a target Peak Inspiratory Pressure (PIP) and a target Positive end-expiratory pressure (PEEP), wherein the total target pressure varies based on the patient.

10. The system as claimed in claim 6, wherein the target oxygen level is a fraction of inspired oxygen (FiO2) in the air mixture