Mechanical ventilation system utilizing bias valve

• US 20060249153A1
• Filed: 07/13/2006
• Published: 11/09/2006
• Est. Priority Date: 08/04/2003
• Status: Active Grant

• Current Assignee: Vyaire Medical 203 Incorporated (Cardinal Health, Inc.)
• Original Assignee: Pulmonetic Systems Incorporated (Cardinal Health, Inc.)
• Inventors: Allum, Todd, DeVries, Douglas F.
• Granted Patent: US 8,118,024 B2
• Time in Patent Office: Days
• US Class Current: 128/204.180
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0057 Pumps therefor
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 16/205 used for exhalation control
• CPC Class Codes: A61M 16/208 Non-controlled one-way valves, e.g. exhalation, check, pop-off non-rebreathing valves
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/003 with a flowmeter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/42 Reducing noise
• CPC Class Codes: F04C 18/126 with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type
• CPC Class Codes: F04C 2220/24 for metering throughflow
• CPC Class Codes: F04C 28/24 characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valvesF04C28/10 takes precedence
• CPC Class Codes: F04C 29/0035 Equalization of pressure pulses silencing F04C29/06

Abstract

A portable mechanical ventilator having a Roots blower is configured to provide a desired gas flow and pressure to a patient circuit. The mechanical ventilator includes a flow meter operative to measure gas flow produced by the Roots blower and an exhalation control module configured to operate an exhalation valve connected to the patient circuit. A bias valve connected between the Roots blower and the patient circuit is specifically configured to generate a bias pressure relative to the patient circuit pressure at the exhalation control module. The bias valve is further configured to attenuate pulsating gas flow produced by the Roots blower such that gas flowing to the mass flow meter exhibits a substantially constant pressure characteristic. The bias pressure facilitates closing of the exhalation valve at the start of inspiration, regulates positive end expiratory pressure during exhalation, and purges sense lines via a pressure transducer module.

Claims

1. A portable mechanical ventilator having a Roots blower for producing gas flow to a patient circuit, the mechanical ventilator comprising:

an exhalation control module configured to operate an exhalation valve connected to the patient circuit; and

a bias valve connected between the Roots blower and the patient circuit and being configured to provide a bias pressure to the exhalation control module.

2. The mechanical ventilator of claim 1 wherein the bias valve is configured to provide a substantially constant bias pressure across a flow range of the Roots blower.

3. The mechanical ventilator of claim 1 wherein:

the Roots blower is controlled by a blower control algorithm;

the bias valve and blower control algorithm collectively regulating flow into and out of the patient circuit during performance of at least one of the following user-activated maneuvers;

inspiratory-hold, expiratory-hold and regulation of mean inspiratory pressure/negative inspiratory force (MIP/NIF).

4. The mechanical ventilator of claim 1 further comprising:

a pressure transducer module fluidly connected to the bias valve and receiving the bias pressure therefrom;

at least one of an airway sense line and a flow sense line connected between the patient circuit and the pressure transducer module;

wherein;

the pressure transducer module is operative to purge the sense lines using the bias pressure.

5. The mechanical ventilator of claim 1 further comprising:

a flow meter interposed between the Roots blower and the bias valve and being operative to measure a gas flow rate of the Roots blower.

6. The mechanical ventilator of claim 5 wherein:

the gas flow produced by the Roots blower is a pulsating gas flow;

the poppet has a mass sufficient to generate inertial damping of the pulsating gas flow for measurement by the flow meter.

7. The mechanical ventilator of claim 5 wherein:

the bias valve includes a cylinder;

the poppet being configured to be reciprocatively slidable within the cylinder and defining a substantially narrow poppet clearance between the poppet and cylinder;

the poppet clearance being sized to generate viscous damping of the pulsating gas flow when gas passes through the poppet clearance during poppet reciprocation.

8. A bias valve for a mechanical ventilator having a Roots blower producing a gas flow, the mechanical ventilator having an exhalation control module fluidly connected to one side of the bias valve and a patient circuit fluidly connected to an opposite side thereof, the exhalation control module being configured to operate an exhalation valve connected to the patient circuit, the bias valve comprising:

a valve seat connected to the Roots blower;

a poppet engageable to the valve seat and being reciprocative between closed and open positions for respectively preventing and allowing gas to flow from the Roots blower to the patient circuit; and

a biasing member configured to bias the poppet against the valve seat such that a bias pressure is provided at the exhalation control module for regulation of the exhalation valve.

9. The bias valve of claim 8 wherein the biasing member has a spring constant sufficient to bias the poppet against the valve seat such that the bias pressure is substantially constant across a flow range of the Roots blower.

10. The bias valve of claim 8 wherein the bias valve is configured to provide a bias pressure sufficient to prevent flow into and out of the patient circuit during performance of at least one of the following user-activated maneuvers:

inspiratory-hold, expiratory-hold and regulation of mean inspiratory pressure/negative inspiratory force (MIP/NIF).

11. The bias valve of claim 8 further comprising:

a pressure transducer module fluidly connected to the bias valve and receiving the bias pressure therefrom;

at least one of an airway and flow sense line connected between the patient circuit and the pressure transducer module and being configured to measure pressure and flow at the patient circuit;

wherein;

the pressure transducer module is operative to purge the sense lines using the bias pressure.

12. The bias valve of claim 8 wherein:

the mechanical ventilator further includes a flow meter interposed between the Roots blower and the bias valve and being operative to measure a gas flow rate of the Roots blower.

13. The bias valve of claim 12 wherein:

the gas flow produced by the Roots blower is a pulsating gas flow;

the poppet having a mass sufficient to provide inertial damping of the pulsating gas flow for measurement by the flow meter.

14. The bias valve of claim 12 further comprising:

a mass element attached to the poppet;

wherein;

the poppet reacts against the pulsating gas flow at a forcing frequency;

the poppet and biasing member being reciprocative at a poppet natural frequency;

the poppet and mass element being sized and configured to maximize inertial damping when the forcing frequency is substantially higher than the poppet natural frequency.

15. The bias valve of claim 14 wherein the bias valve is configured to provide viscous damping of the pulsating gas flow for measurement by the flow meter.

16. The bias valve of claim 15 wherein the bias valve is configured to maximize viscous damping when the forcing frequency is substantially equal to the poppet natural frequency.

17. The bias valve of claim 12 wherein the flow meter is configured as a heated wire mass flow meter.

18. A bias valve for attenuating pulsating gas flow produced by a Roots blower for a mechanical ventilator having an exhalation control module fluidly connected to one side of the bias valve and a patient circuit fluidly connected to an opposite side thereof, the exhalation control module being configured to operate an exhalation valve connected to the patient circuit, the mechanical ventilator having a mass flow meter interposed between the Roots blower and the bias valve and being configured to measure gas flow from the Roots blower, the bias valve comprising:

a housing assembly having an annular housing chamber opening to a housing outlet fluidly connected to the patient circuit and a housing inlet fluidly connected to the Roots blower, the housing assembly including;

a housing having a housing sidewall and a housing end wall, the housing inlet being formed on an end of the elbow housing opposite the housing end wall and being connected to the Roots blower, the housing outlet being formed on the housing sidewall;

a hollow cylinder fixedly mounted within the elbow housing and having a cylinder end wall and a cylinder sidewall, the cylinder sidewall being disposed in spaced coaxial relation to the housing sidewall to define the housing chamber therebetween, the cylinder being open on an end coincident with the housing inlet; and

an annular valve seat fixedly mounted to the housing inlet and having a seat interface;

a poppet slidably disposed within the cylinder and reciprocatively moveable therewithin and having a poppet side and opposing poppet ends, a cylinder chamber being defined between the cylinder end wall and one of the poppet ends, the other one of the poppet ends being configured to be sealingly engageable to the seat interface and defining a seat area; and

a biasing member having a spring preload sufficient to bias the poppet toward the seat interface;

wherein;

the seat area and spring preload being sized and configured to provide a predetermined bias pressure at the exhalation control module.

19. The bias valve of claim 18 wherein the poppet has a mass sufficient to generate inertial damping of the pulsating gas flow from the Roots blower for measurement by the mass flow meter.

20. The bias valve of claim 19 further comprising:

a mass element attached to the poppet;

wherein;

the poppet reacts against the pulsating gas flow at a forcing frequency;

the poppet and biasing member being reciprocative at a poppet natural frequency;

the poppet and mass element being sized and configured to maximize inertial damping when the forcing frequency is substantially higher than the poppet natural frequency.

21. The bias valve of claim 20 wherein the bias valve is configured to provide viscous damping of the pulsating gas flow for measurement by the flow meter.

22. The bias valve of claim 21 wherein the bias valve is configured to maximize viscous damping when the forcing frequency is substantially equal to the poppet natural frequency.

23. The bias valve of claim 21 wherein:

the poppet and cylinder define a substantially narrow poppet clearance therebetween for generating the viscous damping when gas passes through the poppet clearance between the cylinder chamber and the housing chamber during poppet reciprocation.

24. The bias valve of claim 18 wherein the biasing member has a spring constant sufficient to generate a substantially constant bias pressure across a flow range of the Roots blower.