Patent Description:
In general, medical ventilators are mechanical devices that are used to provide respiratory support to a patient. Typically, if a patient is weak or sedated, the patient may be unable to independently perform respiration functions. Hence, the medical ventilators are used for mechanical delivery of a breath to the patient. More specifically, the medical ventilators are used to deliver medical gas under a pressure that is sufficient to overcome patient's airway resistance to fill lungs in an inhalation phase. Further, in an exhalation phase, the medical ventilators may reduce the pressure of the medical gas, which in turn causes the delivered medical gas to flow out of the patient. These inhalation and exhalation phases are repeated alternately to mechanically deliver breath to the patient. In some examples, these medical ventilators may also be used to deliver anesthesia to the patient.

In conventional systems, the medical ventilators require a supply of pressurized medical gas to provide the respiratory support to the patient. In one system, pressurized supply tanks are used for supplying the medical gas to the medical ventilators. However, these supply tanks are also used for providing a drive gas that is used to actuate the medical ventilators. Hence, the supply tanks get used up frequently. Also, these pressurized supply tanks are expensive to use and cumbersome to transport. As a result, operating cost of the system may be substantially increased. In another system, a centralized unit is used for supplying the medical and drive gas. In particular, gas piping and connections are provided in each room in a hospital. Further, these gas connections are connected to the centralized unit to supply the pressurized medical gas to the medical ventilators. However, using the gas connections to supply the medical gas may restrict the mobility of the ventilators and may also increase the set-up cost and the maintenance cost of the system.

Thus, there is a need for an improved system and method for providing respiratory support to a patient. <CIT> discloses an artificial narcosis respiration unit which presents the drive gas for the dome, or for the dome and the control chamber of an overflow valve, with use of a double valve consisting of inhalation and exhalation valves. The unit further includes valves for switching the unit between narcosis and therapy modes of operation. <CIT> discloses a ventilatory system for providing ventilatory support to a patient without the need for an external source of pressurized drive gas. The ventilatory system comprises a drive pump and a controller such that the drive pump collects ambient air and may pressurize it to a pressure determined by the controller. The controller may signal to the drive pump to pressurize the collected ambient air to a first pressure for delivering ventilatory support to a patient and a second pressure for providing PEEP support to a patient. The controller may signal to the drive pump to deliver a targeted flow and/or volume of collected ambient air to the bellows to provide volumetric ventilatory support during inhalation and a PEEP support during exhalation.

In accordance with aspects of the present specification, a ventilator system for providing respiratory support to a patient according to claim <NUM> is presented. The ventilator system includes a controller configured to generate a first control signal for a first time-period and a second control signal for a second time-period during an inspiration time of a ventilation cycle. Also, the ventilator system includes a rotary pump electrically coupled to the controller and configured to change one of a pressure and a flow rate of the drive gas to a first value if the first control signal is received from the controller and change the one of the pressure and the flow rate of the drive gas to a second value if the second control signal is received from the controller, wherein the second value is greater than the first value. Further, the rotary pump is configured to deliver the drive gas to cause supply of a medical gas during the inspiration time, wherein the medical gas is supplied based on the one of the pressure and the flow rate of the drive gas delivered from the rotary pump.

In accordance with another embodiment useful for understanding the invention, a method for providing respiratory support to a patient is presented. The method includes generating, by a controller, a first control signal for a first time-period and a second control signal for a second time-period during an inspiration time of a ventilation cycle. Also, the method includes delivering, by a rotary pump, a drive gas to a bellow assembly. Further, the method includes changing, by the rotary pump, one of a pressure and a flow rate of the drive gas to a first value if the first control signal is received from the controller. In addition, the method includes changing, by the rotary pump, the one of the pressure and the flow rate of the drive gas to a second value if the second control signal is received from the controller, wherein the second value is greater than the first value. Furthermore, the method includes supplying, by the bellow assembly, a medical gas to the patient during the inspiration time based on the one of the pressure and the flow rate of the drive gas received from the rotary pump.

Further disclosed is a ventilator system for providing respiratory support The ventilator system includes a controller configured to generate a first control signal for a first time-period during an inspiration time of a ventilation cycle. Also, the ventilator system includes a rotary pump electrically coupled to the controller and configured to change one of a pressure and a flow rate of the drive gas to a first value based on the first control signal received from the controller. Further, the controller is configured to generate a second control signal for a second time-period during the inspiration time of the ventilation cycle. In addition, the rotary pump is configured to change the one of the pressure and the flow rate of the drive gas to a second value based on the second control signal received from the controller. The rotary pump is further configured to deliver the drive gas to cause supply of a medical gas during the inspiration time, wherein the medical gas is supplied based on the one of the pressure and the flow rate of the drive gas delivered from the rotary pump. Also, the controller is configured to generate a third control signal for a third time-period based on a pressure signal to maintain a pressure of the medical gas to a desired pressure value, wherein the third control signal is generated during an expiration time of the ventilation cycle. Additionally, the rotary pump is configured to change the pressure of the drive gas to a third value based on the third control signal received from the controller. Also, the rotary pump is further configured to deliver the drive gas to maintain the pressure of the medical gas at the desired pressure value during the expiration time of the ventilation cycle.

These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read regarding the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:.

As will be described in detail hereinafter, various embodiments of systems and methods for providing respiratory support to a patient are presented. The systems and methods presented herein employ a rotary pump and a controller to control one or more parameters of medical gas supplied to the patient. Moreover, the rotary pump may use ambient air as a drive gas for driving the medical gas to the patient. As the ambient air is used as the drive gas, pressurized supply tanks are used only for supplying the medical gas. This in turn reduces the usage of the pressurized supply tanks and reduces an operating cost of the system.

In the following specification and the claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the term "or" is not meant to be exclusive and refers to at least one of the referenced components being present and includes instances in which a combination of the referenced components may be present, unless the context clearly dictates otherwise.

As used herein, the terms "may" and "may be" indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of "may" and "may be" indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while considering that in some circumstances, the modified term may sometimes not be appropriate, capable, or suitable.

In some embodiments, a ventilator system for providing respiratory support is presented. The ventilator system includes a controller configured to generate a first control signal for a first time-period and a second control signal for a second time-period during an inspiration time of a ventilation cycle. Also, the ventilator system includes a rotary pump electrically coupled to the controller and configured to change one of a pressure and a flow rate of the drive gas to a first value if the first control signal is received from the controller. Further, the rotary pump is configured to change the one of the pressure and the flow rate of the drive gas to a second value if the second control signal is received from the controller, wherein the second value is greater than the first value. Furthermore, the rotary pump further is configured to deliver the drive gas to cause supply of a medical gas during the inspiration time, wherein the medical gas is supplied based on the one of the pressure and the flow rate of the drive gas delivered from the rotary pump.

Turning now to the drawings and referring to <FIG>, a block diagram of a ventilator system <NUM> for providing respiratory support to a patient <NUM>, in accordance with aspects of the present specification, is depicted. The ventilator system <NUM> is used for mechanical delivery of a medical gas to the patient <NUM>. In one example, the medical gas includes air, oxygen, nitrogen, helium, nitrous oxide, anesthetic agent, drug aerosol, and/or any other gas breathed by the patient.

In general, the ventilator system <NUM> is operated in a cycle known as a respiratory cycle or a ventilation cycle that includes an inhalation phase and an exhalation phase. In the inhalation phase, the ventilator system <NUM> is operated to deliver medical gas under a pressure that is sufficient to overcome patient's airway resistance to fill lungs of the patient <NUM>. It may be noted that a time duration of the inhalation phase is referred to as an "inspiration time" of the ventilation cycle. Further, in the exhalation phase, the ventilator system <NUM> is operated to reduce the pressure of the medical gas, which in turn causes a pressure difference between the delivered medical gas in the lungs of the patient <NUM> and the medical gas in the ventilator system <NUM>. As a result, the delivered medical gas in the patient <NUM> flows out of the patient <NUM>. It may be noted that a time duration of the exhalation phase is referred to as an "expiration time" of the ventilation cycle. Also, the ventilation cycle may be repeated to continuously deliver breath to the patient <NUM>.

In the presently contemplated configuration, the ventilator system <NUM> may be operated in a volume control ventilation (VCV) mode or a pressure control ventilation (PCV) mode based on the requirement or condition of the patient <NUM>. The VCV mode is referred to as a mode of operating the ventilator system <NUM> to control a flow rate of the medical gas supplied to the patient <NUM>. Similarly, the PCV mode is referred to as a mode of operating the ventilator system <NUM> to control a pressure of the medical gas supplied to the patient <NUM>. The aspect of operating the ventilator system <NUM> in the VCV mode or the PCV mode is explained in greater detail with reference to <FIG>. It may be noted that the ventilator system <NUM> may be operated in other modes, and is not limited to the VCV and PCV modes. Also, the method for providing the respiratory support using the ventilator system <NUM> may be performed in other modes, and is not limited to the VCV and PCV modes.

As depicted in <FIG>, the ventilator system <NUM> includes a rotary pump <NUM>, a bellow assembly <NUM>, and a controller <NUM>. It may be noted that the ventilator system <NUM> may include other components and is not limited to the components shown in <FIG>. The rotary pump <NUM> is operatively coupled to the bellow assembly <NUM> and the controller <NUM>. In one example, the rotary pump <NUM> may be a centrifugal pump, an axial pump, a positive displacement pump, or combinations thereof. The rotary pump <NUM> is configured to pressurize ambient air and supply the pressurized ambient air as drive gas to the bellow assembly <NUM>. It may be noted that the drive gas may be referred to as gas that is used for forcing or pushing the medical gas from the bellow assembly <NUM> to the patient <NUM>. Also, the drive gas may be used for actuating an exhaust valve (shown in <FIG>). In one embodiment, the drive gas may include other gases and is not limited to the ambient air as shown in <FIG>. In one example, the rotary pump <NUM> includes a centrifugal blower that is operated at a desired rotary speed to supply a desired volumetric flow rate of the drive gas at a desired pressure to the bellow assembly during the inhalation phase. Also, the rotary speed of the blower may be varied to change the flow rate and/or pressure of the drive gas over the course of the inhalation phase. It may be noted that the terms "rotary speed" and "speed" may be used interchangeably in the below description.

In a presently contemplated configuration, the bellow assembly <NUM> is operatively coupled to the rotary pump <NUM> and the patient <NUM>. Also, the bellow assembly <NUM> is configured to receive a flow of the drive gas from the rotary pump <NUM>. Further, this flow of drive gas actuates or compresses bellows (shown in <FIG>) in the bellow assembly <NUM> so that medical gas within the bellows is supplied to the patient <NUM>.

Further, the controller <NUM> is configured to generate one or more control signals to control one or more parameters of the drive gas supplied to the bellow assembly <NUM>. In general, the parameters of the drive gas are controlled to control the flow of medical gas supplied to the patient <NUM>. The parameters of the drive gas may include a pressure of the drive gas and a flow rate of the drive gas. In one example, the controller <NUM> may include one or more microprocessors or microcontrollers capable of performing parallel processing. Further, as depicted in <FIG>, the controller <NUM> may receive a pressure signal and a flow signal from sensors positioned at suitable locations between the bellow assembly <NUM> and the patient <NUM>. The pressure signal may indicate a pressure of the medical gas supplied from the bellow assembly <NUM> to the patient <NUM>. Similarly, the flow signal may indicate a flow rate of the medical gas supplied from the bellow assembly <NUM> to the patient <NUM>. The controller <NUM> uses the pressure signal and/or the flow signal along with a pre-stored data to control the parameters of the drive gas. In one example, the pre-stored data may include clinician input data, such as respiration rate, a ratio of the inspiration time to the expiration time (I:E ratio), a Positive End Expiratory Pressure (PEEP) value, a tidal volume etc. In one embodiment, the pre-stored data may include other ventilator inputs such as previously provided inputs by the clinician or user to adjust one or more controls of the ventilator system <NUM>.

During the ventilation cycle of the ventilator system <NUM>, the controller <NUM> generates first and second control signals to control the pressure and/or flow rate of the drive gas produced by the rotary pump <NUM>. In particular, the controller <NUM> generates a first control signal for a first time-period at the beginning of the inspiration time of the ventilation cycle. Further, the controller <NUM> generates a second control signal for a second time-period that is after the first time-period during the inspiration time of the ventilation cycle. In one example, the first time-period may be in a range from about <NUM> to about <NUM>. Similarly, the second time-period may be in a range from about <NUM> to about <NUM>.

Further, the controller <NUM> transmits the first control signal to the rotary pump <NUM> for the first time-period. The first control signal is a pulse width modulation (PWM) signal having a constant pulse width that is used to run the rotary pump <NUM> at an intermediate speed for the first time-period. In one embodiment, the rotary pump <NUM> may include a brushless direct current (BLDC) motor. The controller <NUM> may have poor performance to directly ramp up the rotary pump <NUM> to the required speed to supply the drive gas at a desired pressure value or a desired flow rate value to the bellow assembly <NUM>. To overcome this problem, the PWM signal having the constant pulse width is provided to the BLDC motor to run the BLDC motor at the intermediate speed for the first time-period. By running the BLDC motor at the intermediate speed, the controller <NUM> may have better performance to ramp up the BLDC motor from the intermediate speed to the required speed instantaneously for delivering the drive gas at the desired pressure value or the desired flow rate value to the bellow assembly <NUM>. Also, by operating the BLDC motor at the constant speed, the rotary pump <NUM> may change the pressure and/or the flow rate of the drive gas to a first value. In one example, the rotary pump <NUM> includes the centrifugal blower that is operated by the BLDC motor at the constant speed so that the pressure and/or the flow rate of the drive gas is increased to the first value. For example, the pressure of the drive gas is increased from <NUM> to <NUM> H<NUM><NUM>. Similarly, the flow rate of the drive gas is increased from <NUM> to <NUM> lpm.

After the first time-period of the inspiration time, the controller <NUM> transmits the second control signal to the rotary pump <NUM>. The second control signal is a pulse width modulation (PWM) signal having a varying pulse width that is used to vary the speed of the rotary pump <NUM>. The controller <NUM> uses the pressure signal and/or the flow signal along with the pre-stored data to generate the second control signal.

Upon receiving the second control signal, the rotary pump <NUM> is operated to change the pressure or the flow rate of the drive gas to a second value within a shorter time-period. In one example, the shorter time-period is about <NUM>. It may be noted that the second value of the drive gas may correspond to a predetermined value of the medical gas provided by a clinician or an operator to the ventilator system <NUM>. Also, the second value of the drive gas is modified to maintain the predetermined value of the medical gas. In one example, the pulse width of the PWM signal is varied to modify the second value of the drive gas and maintain the predetermined value of the medical gas till the end of the second time-period. Moreover, the second value is greater than the first value. For example, in the PCV mode, the pressure of the drive gas is increased to a value that is in a range from about <NUM> H<NUM><NUM> to about <NUM> H<NUM><NUM>. Similarly, in the VCV mode, the flow rate of the drive gas is increased to a value that is in a range from about <NUM> lpm to about <NUM> lpm. Further, the rotary pump <NUM> may supply this drive gas to the bellow assembly <NUM>. Based on the change in the pressure or the flow rate of the drive gas, the bellow assembly <NUM> is configured to supply the medical gas to the patient <NUM> during the inspiration time of the ventilation cycle. More specifically, with the increase in the pressure and/or the flow rate of the drive gas, the bellows in the bellow assembly <NUM> is compressed so that the medical gas within the bellows is delivered to the patient <NUM>. Also, the pressure of this medical gas may be sufficient to overcome patient's airway resistance to fill lungs of the patient <NUM>.

During the expiration time of the ventilation cycle, the controller <NUM> may generate and transmit a third control signal to the rotary pump <NUM> to reduce the pressure of the drive gas to a third value. The controller <NUM> may use the pressure signal at the end of the inspiration time to generate the third control signal. In one example, the speed of the rotary pump <NUM> is decreased to reduce the pressure and/or the flow rate of the drive gas. Also, the drive gas is stopped from flowing to the bellow assembly <NUM>. As a result, the pressure of the medical gas in the bellows is reduced, which in turn causes a pressure difference between the delivered medical gas in the lungs of the patient <NUM> and the medical gas in the ventilator system <NUM>. As a result, the delivered medical gas in the patient <NUM> flows out of the patient <NUM> and may flow back to the bellows. In one embodiment, the drive gas having the pressure of the third value is supplied to an exhaust valve (shown in <FIG>) to reduce the pressure of the medical gas in the lungs to a desired pressure value or the PEEP value. This pressure of the medical gas in the lungs serves to keep the patient's lungs partially inflated and open. Furthermore, after the expiration time, the ventilator system <NUM> moves to a next ventilation cycle to repeat inhalation and exhalation of the patient. Also, the ventilation cycle may be repeated to continuously deliver breath to the patient.

Referring to <FIG>, a diagrammatical representation of the ventilator system <NUM>, in accordance with some aspects of the present specification, is depicted. The ventilator system <NUM> includes a rotary pump <NUM>, a controller <NUM>, a bellow assembly <NUM>, a flow sensor <NUM>, a pressure sensor <NUM>, an electrical valve <NUM>, an exhaust valve <NUM>, an overpressure valve <NUM>, and a pop-off valve <NUM>.

The rotary pump <NUM> is configured to receive ambient air via an inlet <NUM> and convey the pressurized ambient air as a drive gas via an outlet <NUM> of the rotary pump <NUM>. In one example, an intake filter may be placed at the inlet <NUM> of the rotary pump <NUM> to filter the ambient air. As depicted in <FIG>, the rotary pump <NUM> is operatively coupled to the electrical valve <NUM> and the exhaust valve <NUM>. In one example, the rotary pump is coupled to the electrical valve <NUM> via a first conduit <NUM> and to the exhaust valve <NUM> via a portion of the first conduit <NUM> and a second conduit <NUM>. Also, the rotary pump <NUM> is electrically coupled to the controller <NUM>. In one embodiment, the rotary pump <NUM> includes an electric motor <NUM> that is configured to receive one or more control signals from the controller <NUM>. Further, based on the received control signals, the electric motor <NUM> may vary the speed of the rotary pump <NUM> to control one or more parameters of the drive gas. The parameters may include a pressure of the drive gas and a flow rate of the drive gas. In one example, the electric motor <NUM> may be a BLDC motor.

Further, the electrical valve <NUM> is configured to convey the drive gas to the bellow assembly <NUM>. As depicted in <FIG>, the electrical valve <NUM> is coupled to the bellow assembly <NUM> via a third conduit <NUM>. Also, the electrical valve <NUM> is electrically coupled to the controller <NUM> to receive an activation signal or a deactivation signal. In particular, the electrical valve <NUM> is activated or opened if the activation signal is received from the controller <NUM>. Upon activating or opening the electrical valve <NUM>, the drive gas that is supplied from the rotary pump <NUM> is conveyed to the bellow assembly <NUM>. Similarly, the electrical valve <NUM> is deactivated or closed if the deactivation signal is received from the controller <NUM>. Upon deactivating or closing the electrical valve <NUM>, the supply of drive gas to the bellow assembly <NUM> is ceased or stopped. In one example, the electrical valve <NUM> may include a solenoid valve. It may be noted that activation and deactivation of the electrical valve <NUM> is controlled by the controller <NUM> based on the ventilation cycle of the ventilator system <NUM>.

Furthermore, the overpressure valve <NUM> is operatively coupled to the third conduit <NUM> to maintain the pressure of the drive gas within a threshold pressure value. In particular, the overpressure valve <NUM> is used to vent any excess pressure of the drive gas to the ambient air so that the safety of the patient <NUM> is maintained during ventilation. It may be noted that the excess pressure may be any pressure that is above the threshold pressure value. In one example, the threshold pressure value may be in a range from about <NUM> cmH<NUM>O to <NUM> cmH<NUM>O.

In the illustrated embodiment, the bellow assembly <NUM> includes a bellows chamber <NUM> and a bellows <NUM>. As depicted in <FIG>, the bellows chamber <NUM> is operatively coupled to the third conduit <NUM> to receive the drive gas. Also, the bellows <NUM> is used to store the medical gas that needs to be delivered to the patient <NUM>. In one embodiment, the bellows <NUM> may receive the medical gas from an external gas storage unit (not shown) via an anesthetic and humidifier unit (not shown). In one example, one or more flow control valves may be used between the external gas storage unit (not shown) and the anesthetic and humidifier unit (not shown) to control a flow of medical gas to the bellows <NUM>. Further, the bellows <NUM> may compress or expand based on pressure of the drive gas in the bellows chamber <NUM>. In one example, the external gas storage unit may include one or more pressurized supply tanks. Since the ambient air is used as the drive gas and the pressurized supply tanks are used for supplying only the medical gas, the pressurized supply tanks may be used for a longer period. As a result, operating cost of the ventilator system <NUM> is substantially reduced.

Further, in the inspiration time of the ventilation cycle, the drive gas that is received from the third conduit <NUM> may pressurize the bellows chamber <NUM> and compresses the bellows <NUM> to direct the medical gas within the bellows <NUM> to the patient <NUM> via a fourth conduit <NUM>. In one embodiment, the fourth conduit <NUM> may be coupled to the patient <NUM> through a patient interface unit (not shown) to deliver the medical gas from the bellows <NUM> to the patient <NUM>. In a similar manner, in the expiration time of the ventilation cycle, the pressure of the medical gas in bellows <NUM> is reduced, which in turn causes a pressure difference between the delivered medical gas in the lungs of the patient <NUM> and the medical gas in the ventilator system <NUM>. As a result, the delivered medical gas in the patient <NUM> flows out of the patient <NUM> and may flow back to the bellows <NUM> via the fourth conduit <NUM>. As a result, the bellows <NUM> may expand within the bellow assembly <NUM> to displace or release the drive gas from the bellows chamber <NUM> to the exhaust valve <NUM> via a fifth conduit <NUM> that is coupled between the bellow assembly and the exhaust valve <NUM>. Also, during the expiration time, a portion of the medical gas in the bellows <NUM> may be released to the pop-off valve <NUM> via a sixth conduit <NUM> that is coupled between the bellows <NUM> and the pop-off valve <NUM>. Moreover, if the patient lung pressure is above the set PEEP and the bellows <NUM> is at its topmost position and unable to move further in the bellow assembly <NUM>, the pop-off valve <NUM> opens to convey this portion of the medical gas to the exhaust valve <NUM> via a seventh conduit <NUM> that is coupled between the pop-off valve <NUM> and the exhaust valve <NUM>.

In a presently contemplated configuration, the exhaust valve <NUM> is used to direct any medical gas from the pop-off valve <NUM> and the drive gas from the bellows chamber <NUM> to a scavenging unit <NUM>. Further, the scavenging unit <NUM> is configured to remove any medical gases that may be harmful to clinicians or others in the room with the patient <NUM> if these medical gases were allowed to exhaust into the room. In one embodiment, the scavenging unit <NUM> vents the medical gases out of the hospital or care facility where these medical gases are diluted to non-harmful concentrations in the environment.

In addition, the exhaust valve <NUM> may be configured to control the pressure of the gas in the bellows <NUM> and correspondingly the pressure of the medical gas in the patient's lungs. It may be noted that the pressure of the medical gas in the patient's lungs at the end of the expiration time is known as a positive end expiratory pressure (PEEP). In particular, the pressure of the drive gas supplied to the exhaust valve <NUM> is maintained at the PEEP value so that the patient's exhalation reaches a pressure equilibrium with the medical gas within the bellows <NUM> at the PEEP, thus maintaining the pressure within the patient's lungs. In one embodiment, by controlling the PEEP during patient exhalation, the patient's lungs are not returned to the ambient pressure, but instead are held at a pressure above the ambient pressure that is determined by the clinician. The PEEP serves to keep the patient's lungs partially inflated and open.

Furthermore, the pressure sensor <NUM> may be coupled to the bellow assembly <NUM> to determine the pressure of the medical gas supplied from the bellows <NUM> to the patient <NUM>. In the embodiment of <FIG>, the pressure sensor <NUM> may be coupled to the fourth conduit <NUM>. Further, the pressure sensor <NUM> may transmit a pressure signal to the controller <NUM>. The pressure signal indicates or represents the pressure of the medical gas supplied from the bellows <NUM> to the patient <NUM>. In a similar manner, the flow sensor <NUM> may be coupled to the bellow assembly <NUM> to determine the volume of the medical gas supplied from the bellows <NUM> to the patient <NUM>. It may be noted that the volume of the medical gas per unit time supplied from the bellows is referred to as a flow rate of the medical gas. In the embodiment of <FIG>, the flow sensor <NUM> may be coupled to the fourth conduit <NUM>. Further, the flow sensor <NUM> may transmit a flow signal to the controller <NUM>. The flow signal indicates or represents the flow rate of the medical gas supplied from the bellows <NUM> to the patient <NUM>.

During the operation of the ventilator system <NUM>, the controller <NUM> may begin the ventilation cycle by generating the first control signal for the first time-period of the inspiration time. The controller <NUM> generates the first control signal based on the pre-stored data. In one example, the pre-stored data may include information that is associated with the patient <NUM>. Some of the information includes respiration rate, a ratio of the inspiration time to the expiration time (I:E ratio), a Positive End Expiratory Pressure (PEEP) value, and a tidal volume. In one embodiment, the clinician may provide this information as per the requirement of the patient <NUM>.

Further, the controller <NUM> transmits the first control signal to the rotary pump <NUM> to operate the rotary pump <NUM> at an intermediate speed for the first time-period. The first control signal is a pulse width modulation (PWM) signal having a constant pulse width. In one embodiment, the controller <NUM> may have poor performance to directly ramp up the rotary pump <NUM> to the required speed to supply the drive gas at a desired pressure value or a desired flow rate value to the bellow assembly <NUM>. To overcome this problem, the PWM signal having the constant pulse width is provided to the electric motor to run the electric motor at the intermediate speed for the first time-period. By running the electric motor at the intermediate speed, the controller <NUM> may have better performance to ramp-up the electric motor from the intermediate speed to the required speed for delivering the drive gas at the desired pressure value or the desired flow rate value to the bellow assembly <NUM>.

Also, by operating the rotary pump <NUM> at the constant speed, the pressure and/or flow rate of the drive gas is changed to the first value. Further, the controller <NUM> may concurrently or alternately transmit the activation signal to the electrical valve <NUM> to activate or open the electrical valve <NUM> so that the drive gas is conveyed from the rotary pump <NUM> to the bellow assembly <NUM>.

After operating the rotary pump <NUM> at the constant speed for the first time-period, the controller <NUM> generates the second control signal for the second time-period. The second time-period is after the first time-period of the inspiration time. In particular, the controller <NUM> may receive the pressure signal indicating the pressure of the medical gas from the pressure sensor <NUM>. Also, the controller <NUM> may receive the flow signal indicating the flow rate of the medical gas from the flow sensor <NUM>. Further, the controller <NUM> generates the second control signal based on the pressure and/or the flow rate of the medical gas supplied to the patient <NUM>. More specifically, if the ventilator system <NUM> is operated in the VCV mode, the controller <NUM> generates the second control signal based on the flow rate of the medical gas supplied to the patient <NUM>. Similarly, if the ventilator system <NUM> is operated in the PCV mode, the controller <NUM> generates the second control signal based on the pressure of the medical gas supplied to the patient <NUM>.

Further, the controller <NUM> transmits the second control signal to the rotary pump <NUM> to change the pressure and/or flow rate of the drive gas to the second value. It may be noted that the second value of the drive gas may correspond to a predetermined value of the medical gas provided by a clinician or an operator to the ventilator system <NUM>. Also, the second value of the drive gas is modified to maintain the predetermined value of the medical gas. More specifically, if the ventilator system <NUM> is operated in the VCV mode, the rotary pump <NUM> is operated to change the flow rate of the drive gas from the first value to the second value. In a similar manner, if the ventilator system <NUM> is operated in the PCV mode, the rotary pump <NUM> is operated to the change the pressure of the drive gas from the first value to the second value. The second control signal is a PWM signal that is transmitted to the electric motor <NUM> in the rotary pump <NUM>. The PWM signal is used to vary the rotary speed of the rotary pump <NUM> so as to rapidly increase the pressure and/or flow rate of the drive gas to the second value. Also, the PWM signal is varied to modify the second value of the drive gas and maintain the predetermined value of the medical gas till the end of the second time-period.

As the pressure and/or flow rate of the drive gas is increased to the second value, the drive gas supplied to the bellow assembly <NUM> is pressurized in the bellows chamber <NUM>. As a result, the bellows <NUM> are compressed to direct the medical gas within the bellows <NUM> to the patient <NUM> via the fourth conduit <NUM>. The sum of the first and second time-periods may correspond to total inhalation time set by the clinician. It may be noted that any excess pressure of the drive gas is released to the ambient air via the overpressure valve <NUM> to maintain the safety of the patient <NUM> during the inspiration time of the ventilation cycle.

At the end of the inspiration time, the controller <NUM> may receive the pressure signal from the pressure sensor <NUM>. Further, at the beginning of the expiration time of the ventilation cycle, the controller <NUM> may generate the third control signal based on the pressure of the medical gas supplied to the patient <NUM>. Also, the controller <NUM> transmits the deactivation signal to the electrical valve <NUM> to deactivate or close the electrical valve <NUM> so as to cease the flow of drive gas to the bellow assembly <NUM>. Additionally, upon closing the electrical valve <NUM>, the drive gas is supplied from the rotary pump <NUM> to the exhaust valve <NUM> via the portion of the first conduit <NUM> and the second conduit <NUM>, as depicted in <FIG>.

Furthermore, the controller <NUM> transmits the third control signal to the rotary pump <NUM> to change the pressure of the drive gas to the third value. It may be noted that the third value of the drive gas is same as the PEEP value or a desired pressure value of the medical gas supplied to the patient <NUM>. More specifically, the controller <NUM> transmits the third control signal to the rotary pump <NUM> to reduce the pressure of the medical gas in the patient <NUM> to the PEEP value or the desired value. Also, the exhaust valve <NUM> receives the drive gas having the pressure of the third value from the rotary pump <NUM>. Further, the exhaust valve <NUM> maintains the pressure of the medical gas at the desired pressure value as a result of the drive gas having the pressure of the third value received from the rotary pump <NUM>. Therefore, the pressure of the medical gas is maintained at the desired pressure value during the expiration time of the ventilation cycle. In one embodiment, the third control signal may be a PWM signal that is used to vary the speed of the rotary pump <NUM> so that the pressure of the drive gas is reduced from the second value to the third value.

At the end of the expiration time of the ventilation cycle, the controller <NUM> along with the exhaust valve <NUM> reduces the pressure of the medical gas to the PEEP value or the desired value. In one embodiment, if the ventilator system <NUM> is operated in the VCV mode, the controller <NUM> continues to generate the third control signal till the end of the expiration time to maintain the pressure of the medical gas to the PEEP value or the desired value. However, if the ventilator system <NUM> is operated in the PCV mode, the pressure of the medical gas is reduced to the PEEP value or the desired value at least before a fourth time-period at an end of the expiration time of the ventilation cycle. In one example, the fourth time-period is in a range from about <NUM> to about <NUM>. In one embodiment, the electric motor <NUM> in the rotary pump <NUM> may be unable to ramp up to a predefined speed instantaneously. As a consequence, the rotary pump <NUM> may have a slow response time to supply the drive gas at a desired pressure value or a desired flow rate value to the bellow assembly <NUM> during the inspiration time. To improve a response time of the rotary pump <NUM>, the controller <NUM> generates a fourth control signal for the fourth time-period at the end of the expiration time. Further, the rotary pump <NUM> receives the fourth control signal and changes the pressure of the drive gas to a fourth value. The fourth value is greater than the third value and less than the first value. Also, when the ventilator system <NUM> starts the next ventilation cycle, the controller <NUM> generates the first control signal to increase the pressure of the drive gas from the fourth value to the first value. As a result, the electric motor <NUM> in the rotary pump <NUM> is already operating at an intermediate speed corresponding to the fourth value and therefore electric motor <NUM> takes shorter time-period to go to the speed required to increase the pressure of the drive gas to the second value. In one example, the shorter time-period may be about <NUM>.

Turing now to <FIG>, a block diagram of a controller <NUM> employed in the ventilator system <NUM> to control one or more parameters of medical gases, in accordance with aspects of the present specification, is depicted. The controller <NUM> includes a processing unit <NUM>, a memory <NUM>, a first drive card <NUM>, and a second drive card <NUM>. The memory <NUM> includes pre-stored data associated with the patient <NUM>. Also, the memory <NUM> may be used to store other data provided by the clinician or the user via an interface unit (not shown). Further, the memory <NUM> is electrically coupled to the processing unit <NUM>.

As depicted in <FIG>, the processing unit <NUM> is electrically coupled to the first drive card <NUM> and the second drive card <NUM>. Also, the processing unit <NUM> is electrically coupled to the flow sensor <NUM> and the pressure sensor <NUM>. It may be noted that the processing unit <NUM> and/or the first drive card <NUM> may include a proportional-integral-derivative (PID) controller that is used to generate PWM signals. In one embodiment, the processing unit <NUM> may receive power supply from a power unit <NUM> that is positioned external to the controller <NUM>. It may be noted that the power unit <NUM> may be positioned within the controller <NUM> or outside the controller <NUM>. In one example, the processing unit <NUM> may receive a voltage that is in a range from about <NUM> V to about <NUM> V from the power unit <NUM>.

In a similar manner, the first drive card <NUM> and the second drive card <NUM> may receive the power supply from the power unit <NUM>. In one example, the first and second drive cards <NUM>, <NUM> may receive a voltage that is in a range from about <NUM> V to about <NUM> V from the power unit <NUM>. Also, the first drive card <NUM> is electrically coupled to the rotary pump <NUM> and configured to drive or control the speed of the rotary pump <NUM>. Similarly, the second drive card <NUM> is electrically coupled to the electrical valve <NUM> and configured to activate and deactivate the electrical valve <NUM>.

In one embodiment, the processing unit <NUM> generates a first low voltage signal. In one example, the magnitude of the first low voltage signal is in a range from about <NUM> V to about 8V. Further, the processing unit <NUM> transmits the first low voltage signal to the first drive card <NUM>. Also, the first drive card <NUM> receives the voltage from the power unit <NUM>. In one example, the magnitude of the voltage received from the power unit <NUM> is about <NUM> V. Thereafter, the first drive card <NUM> generates a PWM signal having a varying pulse width based on the first low voltage signal and the voltage received from the power unit <NUM>. More specifically, the pulse width of the PWM signal is varied based on the magnitude of the first low voltage signal received from the processing unit <NUM>. Also, the magnitude of the PWM signal is selected corresponding to the magnitude of the voltage received from the power unit <NUM>. Furthermore, the first drive card <NUM> transmits the generated PWM signal having the varying pulse width as a control signal to the rotary pump <NUM> to control the speed of the rotary pump <NUM>. The control signal may be one of the first control signal, the second control signal, the third control signal, and the fourth control signal as referred to in <FIG>.

In another embodiment, the processing unit <NUM> generates a PWM signal having a varying pulse width. In one example, the magnitude of the PWM signal is about <NUM> V. Further, the PWM signal having the varying pulse width is transmitted to the first drive card <NUM>. Also, the first drive card <NUM> receives the voltage from the power unit <NUM>. In one example, the magnitude of the voltage received from the power unit <NUM> is about <NUM> V. Thereafter, the first drive card <NUM> amplifies or increases the magnitude of the PWM signal that is corresponding to the magnitude of the voltage received from the power unit <NUM>. In one example, the magnitude of the PWM signal varies from <NUM> V to <NUM> V. Furthermore, the first drive card <NUM> transmits the amplified PWM signal having the varying pulse width and the varying magnitude as a control signal to the rotary pump <NUM> to control the speed of the rotary pump <NUM>.

In yet another embodiment, the processing unit <NUM> generates and transmits a PWM signal having a predefined or constant pulse width to the first drive card <NUM>. Further, the first drive card <NUM> varies the magnitude of the PWM signal based on the magnitude of the voltage received from the power unit. Furthermore, the first drive card <NUM> transmits the PWM signal having a varying magnitude and constant pulse width as a control signal to the rotary pump <NUM> to control the speed of the rotary pump <NUM>.

In a similar manner, the processing unit <NUM> generates a second low voltage signal. In one example, the magnitude of the second low voltage signal is in a range from about <NUM> V to about 5V. Also, the processing unit <NUM> transmits the second low voltage signal to the second drive card <NUM>. Further, the second drive card <NUM> uses the voltage received from the power unit <NUM> to amplify the second low voltage signal and transmits the amplified second low voltage signal as an activation signal or a deactivation signal to the electrical valve <NUM> to open or close the electrical valve <NUM>. In one example, the magnitude of the activation signal or the deactivation signal is in a range from about <NUM> V to about <NUM> V.

Referring to <FIG>, a time chart <NUM> of a ventilator system <NUM> operated in a volume control ventilation (VCV) mode, in accordance with aspects of the present specification, is depicted. Reference numeral <NUM> represents the ventilation cycle of the ventilator system <NUM>. Further, reference numeral <NUM> represents an inspiration time of the ventilation cycle <NUM>. Also, reference numeral <NUM> represents an expiration time of the ventilation cycle <NUM>.

Further, reference numeral <NUM> represents the first time-period of the inspiration time <NUM>. In the first time-period <NUM>, the controller <NUM> generates a first control signal to operate the rotary pump <NUM> at a constant speed. Also, the flow rate of the drive gas is increased to a first value. Similarly, reference numeral <NUM> represents the second time-period of the inspiration time <NUM>. In the second time-period <NUM>, the controller <NUM> generates a second control signal to increase and maintain the flow rate of the drive gas to a second value.

In the expiration time <NUM> of the ventilation cycle <NUM>, reference numeral <NUM> represents a third time-period where the controller <NUM> generates a third control signal to reduce the pressure of the drive gas to a third value. Also, in the third time-period <NUM>, the pressure of the medical gas supplied to the patient <NUM> is reduced or maintained at a desired pressure value or a PEEP value.

Referring to <FIG>, a time chart <NUM> of a ventilator system <NUM> operated in a pressure control ventilation (PCV) mode, in accordance with aspects of the present specification, is depicted. Reference numeral <NUM> represents the ventilation cycle of the ventilator system <NUM>. Further, reference numeral <NUM> represents an inspiration time of the ventilation cycle <NUM>. Also, reference numeral <NUM> represents an expiration time of the ventilation cycle <NUM>.

Further, reference numeral <NUM> represents the first time-period of the inspiration time <NUM>. In the first time-period <NUM>, the controller <NUM> generates a first control signal to operate the rotary pump <NUM> at a constant speed. Also, the pressure of the drive gas is increased to a first value. Similarly, reference numeral <NUM> represents the second time-period of the inspiration time <NUM>. In the second time-period <NUM>, the controller <NUM> generates a second control signal to increase and maintain the pressure of the drive gas to a second value.

In the expiration time <NUM> of the ventilation cycle <NUM>, reference numeral <NUM> represents a third time-period where the controller <NUM> generates a third control signal to reduce the pressure of the drive gas to a third value. Also, in the third time-period <NUM>, the pressure of the medical gas supplied to the patient <NUM> is reduced or maintained at a desired pressure value or PEEP value. Further, reference numeral <NUM> represents a fourth time-period at the end of the expiration time <NUM>. In the fourth time-period <NUM>, the controller <NUM> generates a fourth control signal to change the pressure of the drive gas from the third value to a fourth value. In one example, the fourth value is greater than the third value and less than the first value.

Referring to <FIG>, a flow chart illustrating a method <NUM> for providing respiratory support to a patient, in accordance with aspects useful for understanding the invention. For ease of understanding, the method <NUM> is described with reference to the components of <FIG>. The method <NUM> begins with generating, by a controller, a first control signal for a first time-period and a second control signal for a second time-period during an inspiration time of a ventilation cycle, as shown in step <NUM>. The controller may generate the first control signal at the beginning of the inspiration time. In one embodiment, the first control signal is generated based on the pre-stored data associated with the patient. Similarly, the controller may generate the second control signal after the first time-period of the inspiration time. In one embodiment, the second control signal is generated based on the pressure signal and/or the flow signal received by the controller.

Subsequently, at step <NUM>, the method includes delivering, by a rotary pump, a drive gas to a bellow assembly. More specifically, the rotary pump is operatively coupled to the bellow assembly and the controller. Further, the rotary pump is configured to pressurize ambient air and supply the pressurized ambient air as drive gas to the bellow assembly.

In addition, at step <NUM>, the method includes changing, by the rotary pump, one of a pressure and a flow rate of the drive gas to a first value if the first control signal is received from the controller. The rotary pump receives the first control signal for the first time-period of the inspiration time. Further, based on the first control signal, the rotary pump is operated at an intermediate speed to improve the controller performance for delivering a proper supply of the drive gas to the bellow assembly. Also, by operating the rotary pump at the intermediate speed, the rotary pump may change the pressure and/or the flow rate of the drive gas to a first value.

Furthermore, at step <NUM>, the method includes changing, by the rotary pump, the one of the pressure and the flow rate of the drive gas to a second value if the second control signal is received from the controller, wherein the second value is greater than the first value. The rotary pump receives the second control signal for the second time-period of the inspiration time. Further, the rotary pump is operated to change and maintain the pressure and/or the flow rate of the drive gas to a second value. The second value is greater than the first value. Further, the rotary pump may supply this drive gas to the bellow assembly.

In addition, at step <NUM>, the method includes supplying, by the bellow assembly, a medical gas to the patient during the inspiration time based on the one of the pressure and the flow rate of the drive gas received from the rotary pump. More specifically, with the increase in the pressure and/or the flow rate of the drive gas, the bellows in the bellow assembly is compressed so that the medical gas within the bellows is delivered to the patient. Also, the pressure of this medical gas is sufficient to overcome patient's airway resistance to fill the lungs of the patient.

Moreover, at step <NUM>, the method includes generating, by the controller, a third control signal for a third time-period during an expiration time of the ventilation cycle. The controller receives a pressure signal associated with the pressure of the medical gas from the pressure sensor at an end of the inspiration time of the ventilation cycle. Further, the controller generates the third control signal for a third time-period based on the pressure signal to reduce and maintain the pressure of the medical gas to a desired pressure value.

Subsequently, at step <NUM>, the method includes maintaining, by an exhaust valve <NUM>, the pressure of the medical gas at a desired pressure value during the expiration time of the ventilation cycle. More specifically, the rotary pump changes the pressure of the drive gas to a third value based on the third control signal received from the controller. Further, the exhaust valve receives the drive gas having the pressure of the third value from the rotary pump. Thereafter, the exhaust valve maintains or reduces the pressure of the medical gas at the desired pressure value based on the drive gas having the pressure of the third value received from the rotary pump.

The various embodiments of the exemplary systems and methods presented hereinabove aid in providing respiratory support to a patient. Also, the exemplary systems and methods presented hereinabove uses the ambient air as a drive gas for supplying the medical gas to the patient. As the ambient air is used as the drive gas, pressurized supply tanks are used only for supplying the medical gas. This in turn minimizes usage of the pressurized supply tanks and reduces the operating cost of the system.

Claim 1:
A ventilator system for providing respiratory support, the ventilator system comprising:
a controller (<NUM>) configured to generate a first control signal for a first time-period based on a pre-stored data, and a second control signal for a second time-period during an inspiration time of a ventilation cycle based on at least one of a pressure and a flow rate of the medical gas supplied from the bellow assembly to the patient during the inspiration time of the ventilation cycle, wherein the second time-period is after the first time-period during the inspiration time and wherein the first control signal is a pulse width modulation signal having a constant pulse width and the second control signal is a pulse width modulation signal having a varying pulse width;
a bellow assembly (<NUM>);
a rotary pump (<NUM>) electrically coupled to the controller and configured to:
run an intermediate speed to change one of a pressure and a flow rate of a drive gas to a first value if the first control signal is received from the controller; and
vary the speed of the pump to change the one of the pressure and the flow rate of the drive gas to a second value if the second control signal is received from the controller, wherein the second value is greater than the first value; and
the rotary pump further configured to deliver the drive gas to the bellow assembly (<NUM>), wherein the bellow assembly is configured to supply a medical gas during the inspiration time based on the one of the pressure and the flow rate of the drive gas delivered from the rotary pump.