Compensation for unmeasurable inspiratory flow in a critical care ventilator

Patent metadata

Field	Value
Publication number	US-9358356-B2
Application number	US-201314023975-A
Country	US
Kind code	B2
Filing date	Sep 11, 2013
Priority date	Jan 28, 2010
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

A system and method for operating a ventilator to compensate for external gas flow reaching a patient from an external device, such as a nebulizer. A control unit of the ventilator monitors the gas flow rate from the ventilator and compares the gas flow rate from the ventilator to an expired gas flow rate from the patient. The difference between the inspired flow rate and the expired flow rate is due to the external device. The control unit modifies the operation of the ventilator to compensate for the external gas flow rate such that the flow of gas reaching the patient is maintained at a desired level.

First claim

We claim:

1. A method of operating a ventilator to provide an inspiratory gas flow to a patient including an external gas flow from a medical device that operates separately and independently from the operation of the ventilator and without communication with the ventilator, the method comprising the steps of:
setting a desired inspiratory flow rate in a control unit of the ventilator;
monitoring a flow of gas from only the ventilator in the control unit of the ventilator utilizing an inspiratory sensor of the ventilator;
monitoring an expiratory flow of gas from the patient in the control unit of the ventilator utilizing an expiratory sensor of the ventilator;
determining an external flow rate from the medical device in the control unit of the ventilator based on the difference between the expiratory flow rate and the ventilator flow rate; and
operating the control unit of the ventilator to reduce the ventilator flow rate based upon the determined external flow rate such that the combination of the reduced ventilator flow rate and the external flow rate provides the desired inspiratory flow rate to the patient.

2. The method of claim 1 wherein the flow of gas from the ventilator and the expiratory flow of gas are determined by the inspiratory sensor and the expiratory sensor contained within the ventilator.

3. The method of claim 2 wherein the external gas flow is injected into the flow of gas from the ventilator downstream from the inspiratory sensor contained within the ventilator.

4. The method of claim 1 wherein the external gas is provided by a nebulizer that provides a nebulized agent in a nebulizer gas flow.

5. The method of claim 1 wherein the desired inspiratory flow rate for the patient is determined in the control unit of the ventilator based upon user input.

6. The method of claim 5 wherein the desired inspiratory flow rate is determined through the user input entered into a user input device of the ventilator, wherein the user input device is coupled to the control unit.

7. A method of adjusting a flow rate from a ventilator to compensate for a gas flow from a nebulizer that operates separately and independently from the operation of the ventilator and without communication with the ventilator to provide a desired inspiratory flow rate to a patient, comprising the steps of:
setting a desired inspiratory flow rate in a control unit of the ventilator;
monitoring the flow of gas from only the ventilator in the control unit of the ventilator utilizing an inspiratory sensor of the ventilator;
monitoring an expiratory flow of gas from the patient utilizing an expiratory sensor of the ventilator;
determining a nebulizer flow rate in the control unit of the ventilator based upon the difference between the expiratory flow rate and the ventilator flow rate; and
operating the control unit of the ventilator to reduce the ventilator flow rate such that the combination of the nebulizer flow rate and the ventilator flow rate reaches the desired inspiratory flow rate.

8. The method of claim 7 wherein the flow of gas from the ventilator and the expiratory flow are determined by the inspiratory sensor and the expiratory sensor contained within the ventilator.

9. The method of claim 8 wherein the nebulized agent is injected into the flow of gas from the ventilator downstream from the inspiratory sensor contained within the ventilator.

10. The method of claim 7 wherein the desired inspiratory flow rate for the patient is determined in the control unit of the ventilator based upon user input.

11. The method of claim 10 wherein the desired inspiratory flow rate is determined based on a desired breath volume entered into a user input device of the ventilator, wherein the user input device is coupled to the control unit.

12. The method of claim 7 further comprising the steps of:
assigning a reference flow rate to the nebulizer flow rate prior to determination of the nebulizer flow rate;
reducing the flow rate from the ventilator by the reference flow rate; and
providing the reduced ventilator flow rate to the patient prior to determining the nebulizer flow rate.

Assignees

• Gen Electric

Inventors

• Hunsicker Paul
• Stephenson Matthew Michael
• Payne Jessica B

Classifications

• A61M11/00

  Sprayers or atomisers specially adapted for therapeutic purposes (in general B05B; {aerosol containers B65D83/14}) · CPC title

• A61M16/024

  including calculation means, e.g. using a processor · CPC title

• A61M16/0057

  Pumps therefor · CPC title

• A61M16/14

  by mixing different fluids, one of them being in a liquid phase · CPC title

• A61M2016/0042

  in the expiratory circuit · CPC title