SYSTEMS AND METHODS FOR DETERMINING PATIENT EFFORT AND/OR RESPIRATORY PARAMETERS IN A VENTILATION SYSTEM

• US 20090301490A1
• Filed: 06/05/2009
• Published: 12/10/2009
• Est. Priority Date: 06/06/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Masic, Milenko
• Granted Patent: US 8,826,907 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• 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 and providing a measured pressure;

measuring an inlet flow and an outlet flow, and providing a measured net flow;

using 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 to provide a prediction of patient effort; and

updating an interim value based at least in part on the prediction of the patient effort.

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

5. The method of claim 4, wherein calculating the third value related to 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 (ε

), a filtered pressure value (z), a regression vector (φ

^T), and a current estimated value of a parameter vector (Θ

).

6. The method of claim 1, wherein the interim value includes one or more variables from the group selected from:

a time dependent signal, and a respiratory parameter.

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 parameters selected from:

lung compliance (C_L), patient resistance (R_P), tubing compliance (C_T), and leakage (λ

_LEAK).

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 (ε

), a filtered pressure value (z), a regression vector (φ

^T), 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 the regression form:

z=Θ

^Tφ

+φ

_d.

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

16. The method of claim 15, wherein the transfer function is derived from the model:

$\left[\begin{array}{c}{\stackrel{.}{p}}_Y\\ {\stackrel{.}{p}}_L\end{array}\right]=\left[\begin{array}{cc}-\frac{1}{C_T<br><br>R_P}& \frac{1}{C_T<br><br>R_P}\\ \frac{1}{C_L<br><br>R_P}& -\frac{1}{C_L<br><br>R_P}\end{array}\right][<br><br>\begin{array}{c}{p}_Y\\ p_L\end{array}]+\hspace{1em}<br><br>\left[\begin{array}{ccc}\frac{1}{C_T}& \frac{1}{C_T}& -\frac{1}{C_T}\\ 0& 0& 0\end{array}\right]<br><br>\left[\begin{array}{c}{q}_{\mathrm{AIR}}\\ q_{O<br><br><br><br>2}\\ q_E\end{array}\right]+\left[\begin{array}{ccc}0& -\frac{1}{C_T}& 0\\ 1& 0& -\frac{1}{C_T}\end{array}\right]<br><br>\left[\begin{array}{c}{\stackrel{.}{p}}_P\\ q_{\mathrm{Tleak}}\\ q_{\mathrm{Pleak}}\end{array}\right]$

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

).

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

mathematically combining at least the inlet flow and the outlet flow to yield the measured 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;

receive an inlet flow;

receive an outlet flow;

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

use 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 to provide a prediction of patient effort; and

update an interim value based at least in part on the prediction of the patient effort.

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 and providing a measured pressure;

measuring an inlet flow and an outlet flow, and providing a measured net flow;

using a relationship between a first value related to the measured pressure, a second value related to the measured net flow and the parameter set to provide a prediction of patient effort; and

updating an interim value based at least in part on the prediction of the patient effort.

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 provide a measured pressure value indicating a pressure in the tube;

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

a second flow sensor, wherein the second flow sensor is operable to provide an outlet flow value indicating a 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 value;

receive the inlet flow value;

receive the outlet flow value;

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

use a relationship between a first value related to the measured pressure value, a second value related to the measured net flow, and a third value related to patient effort to provide a prediction of patient effort; and

update an interim value based at least in part on the prediction of the patient effort.

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

measuring a pressure to generate a measured pressure;

measuring a flow to generate a measured flow;

using the dynamic model;

$\left[\begin{array}{c}{\stackrel{.}{p}}_Y\\ {\stackrel{.}{p}}_L\end{array}\right]=\left[\begin{array}{cc}-\frac{1}{C_T<br><br>R_P}& \frac{1}{C_T<br><br>R_P}\\ \frac{1}{C_L<br><br>R_P}& -\frac{1}{C_L<br><br>R_P}\end{array}\right][<br><br>\begin{array}{c}{p}_Y\\ p_L\end{array}]+\hspace{1em}<br><br>\left[\begin{array}{ccc}\frac{1}{C_T}& \frac{1}{C_T}& -\frac{1}{C_T}\\ 0& 0& 0\end{array}\right]<br><br>\left[\begin{array}{c}{q}_{\mathrm{AIR}}\\ q_{O<br><br><br><br>2}\\ q_E\end{array}\right]+\left[\begin{array}{ccc}0& -\frac{1}{C_T}& 0\\ 1& 0& -\frac{1}{C_T}\end{array}\right]<br><br>\left[\begin{array}{c}{\stackrel{.}{p}}_P\\ q_{\mathrm{Tleak}}\\ q_{\mathrm{Pleak}}\end{array}\right]$

to provide a prediction of a patient effort.

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

measuring a pressure to generate a measured pressure;

measuring a flow to generate a measured flow;

using the parameterized system input to output relationship in the regression form.