Systems and methods for determining patient effort and/or respiratory parameters in a ventilation system

• US 9,925,345 B2
• Filed: 08/08/2014
• Issued: 03/27/2018
• Est. Priority Date: 06/06/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Masic, Milenko
• Primary Examiner(s): Ho, (Jackie) Tan-Uyen T
• Assistant Examiner(s): Paciorek, Jonathan
• Application Number:
  US14/455,472
• Publication Number:
  US 20140345616A1
• Time in Patent Office: 1,327 Days
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0057 Pumps therefor
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 2016/0015 inhalation detectors
• CPC Class Codes: A61M 2016/0018 electrical
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit
• CPC Class Codes: A61M 2205/3303 Using a biosensor
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: G01F 1/00 Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow measuring a proportion of the volume flow G01F5/00
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure

Abstract

Various embodiments of the present disclosure provide systems, methods and devices for respiratory support. As one example, a method for respiratory support is described that includes measuring a pressure, providing a measured pressure, measuring an inlet flow and an outlet flow, and providing a measured net flow. A relationship between a first value related to the measured pressure, a second value related to the measured net flow and a third value related to patient effort is used to provide a prediction of patient effort. An interim value is updated based at least in part on the prediction of the patient effort.

Claims

1. A method for respiratory support, the method comprising:

measuring a pressure;

measuring an inlet flow and an outlet flow;

based on the inlet flow and the outlet flow, calculating a net flow;

predicting patient effort based at least in part on a relationship between a first value related to the measured pressure, a second value related to the net flow, and a third value related to patient effort; and

updating an interim value based at least in part on the prediction of the patient effort, wherein the interim value does not directly correspond to a respiratory parameter.

2. The method of claim 1, wherein the third value related to patient effort is an actual patient effort.

3. The method of claim 1, wherein the third value related to patient effort is a derivative of patient effort.

4. The method of claim 1, wherein the method further comprises:

calculating patient effort based at least in part on the interim value.

5. The method of claim 4, wherein calculating the patient effort includes estimating patient effort based on a combination of one or more values selected from a group consisting of:

an estimated normalized prediction error, a filtered pressure value, a regression vector, and a current estimated value of a parameter vector.

6. The method of claim 1, wherein the interim value is a time dependent signal.

7. The method of claim 1, wherein the interim value includes a respiratory parameter set, and wherein the respiratory parameter set is a vector including a combination of one or more respiratory parameters selected from:

lung compliance, patient resistance, tubing compliance, and leakage.

8. The method of claim 1, wherein the interim value includes a time dependent estimator of patient effort.

9. The method of claim 8, wherein the time dependent estimator of the patient effort is an estimate of patient effort.

10. The method of claim 9, wherein the estimate of patient effort is based on a combination of one or more values selected from a group consisting of:

an estimated normalized prediction error, a filtered pressure value, a regression vector, and a current estimated value of a parameter vector.

11. The method of claim 1, wherein the second value is selected from a group consisting of:

a filtered version of the measured net flow, and the measured net flow.

12. The method of claim 1, wherein the first value is selected from a group consisting of:

a filtered version of the measured pressure and the measured pressure.

13. The method of claim 1, wherein the relationship is a parameterized system input to output relationship.

14. The method of claim 13, wherein the parameterized system input to output relationship is a regression form:

z=Θ

φ

+φ

_d, wherein z is a filtered pressure value, Θ

is a current estimated value of a parameter vector, φ

is at least a part of a regression vector, and φ

_d is a filtered patient effort.

15. The method of claim 14, wherein the parameterized system input to output relationship is derived from a transfer function.

16. The ventilation system of claim 15, wherein the transfer function is derived from a model comprising:

17. The method of claim 1, wherein an estimate of the prediction patient effort is calculated using the approximation:

φ

_d≈

e<sup>−

s·

dt</sup>(z−

Θ

^Tφ

), wherein φ

_d is a filtered patient effort, z is a filtered pressure value, Θ

^T is a current estimated parameter vector, φ

is at least a part of regression vector, t is a variable of time, and s is a spatial variable.

18. The method of claim 1, wherein providing the net flow includes:

mathematically combining at least the inlet flow and the outlet flow to yield the net flow.

19. A ventilation system, the ventilation system comprising:

a processor communicably coupled to a computer readable medium, wherein the computer readable medium includes instructions executable by the processor to;

receive a pressure;

calculate a net flow based at least in part on an inlet flow and an outlet flow;

predict patient effort based at least in part on a relationship between a first value related to the pressure, a second value related to the net flow, and a third value related to patient effort; and

update an interim value based at least in part on the predicted patient effort, wherein the interim value does not directly correspond to a respiratory parameter.

20. The system of claim 19, wherein the computer readable medium further includes instructions executable by the processor to:

calculate a patient effort value based at least in part on the interim value.

21. A method for respiratory support, the method comprising:

receiving a parameter set of one or more parameters;

measuring a pressure;

determining a net flow;

predicting patient effort based at least in part on a relationship between a first value related to the measured pressure, a second value related to the net flow, and the parameter set; and

updating an interim value based at least in part on the prediction of the patient effort, wherein the interim value does not directly correspond to an identifiable respiratory parameter.

22. The method of claim 21, wherein the parameter set comprises a parameter related to a circuit resistance.

23. The method of claim 21, wherein the parameter set comprises a parameter related to a circuit compliance.

24. A patient ventilator, the ventilator comprising:

a gas inlet;

a gas outlet;

a tube coupling the gas inlet and the gas outlet;

a pressure sensor, wherein the pressure sensor is operable to measure a pressure in the tube;

a first flow sensor, wherein the first flow sensor is operable to measure an inlet flow associated with the gas inlet;

a second flow sensor, wherein the second flow sensor is operable to measure an outlet flow associated with the gas outlet; and

a processor communicably coupled to a computer readable medium, wherein the computer readable medium includes instructions executable by the processor to;

receive the measured pressure;

receive the inlet flow;

receive the outlet flow;

calculate a net flow value based at least in part on the inlet flow and the outlet flow;

predict patient effort based at least in part on a relationship between the measured pressure, the net flow, and a value related to patient effort; and

update an interim value based at least in part on the predicted patient effort, wherein the interim value does not directly correspond to an identifiable respiratory parameter.

25. A method for respiratory support, the method comprising:

measuring a pressure;

calculating a net flow;

using a dynamic model;