Systems and methods for triggering and cycling a ventilator based on reconstructed patient effort signal

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

providing a measured pressure;

calculating a net flow based on at least one measured inlet flow and at least one measured outlet 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;

updating an interim value based at least in part on the prediction of patient effort, wherein the interim value is one of a covariance matrix and a parameter vector;

calculating a computed patient effort based at least in part on the interim value; and

utilizing the computed patient effort to trigger a ventilation cycle.

2. The method of claim 1 , wherein the computed patient effort is a filtered patient effort signal.

3. The method of claim 1 , wherein the computed patient effort is a linear function of a derivative of actual patient effort.

4. The method of claim 3 , wherein the linear function includes a filter function.

5. The method of claim 1 , wherein utilizing the computed patient effort to trigger the ventilation cycle includes determining a negative zero crossing of the computed patient effort, and initiating the ventilation cycle based at least in part on the negative zero crossing of the computed patient effort.

6. The method of claim 1 , wherein utilizing the computed patient effort to trigger the ventilation cycle includes determining a positive zero crossing of the computed patient effort, and terminating the ventilation cycle based at least in part on the positive zero crossing of the computed patient effort.

7. The method of claim 1 , wherein utilizing the computed patient effort to trigger the ventilation cycle includes determining an onset condition related to the computed patient effort, and initiating the ventilation cycle based at least in part on the onset condition.

8. The method of claim 7 , wherein the computed patient effort is a function of a derivative of actual patient effort, and wherein determining the onset condition includes determining whether the computed patient effort passes through a threshold value with a negative slope.

9. The method of claim 8 , wherein determining the onset condition occurs outside of an inspiration cycle.

10. The method of claim 8 , wherein the threshold value is zero.

11. The method of claim 1 , wherein utilizing the computed patient effort to trigger the ventilation cycle includes determining an end condition, and terminating the ventilation cycle based at least in part on the end condition.

12. The method of claim 11 , wherein the computed patient effort is a function of a derivative of actual patient effort, and wherein determining the end condition includes determining whether the computed patient effort passes through a threshold value with a positive slope.

13. The method of claim 12 , wherein determining the end condition occurs during an inspiration cycle.

14. The method of claim 12 , wherein the threshold value is zero.

15. 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 at least one of an inlet flow and an outlet flow;

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

update an interim value based at least in part on the prediction of patient effort, wherein the interim value is one of a covariance matrix and a parameter vector;

calculate a computed patient effort based at least in part on the interim value; and

initiate a ventilation cycle based at least in part on the computed patient effort.

16. The system of claim 15 , wherein initiating the ventilation cycle includes determining an end condition, and terminating the ventilation cycle based at least in part on the end condition.

17. The system of claim 16 , wherein the computed patient effort is a function of a derivative of actual patient effort, and wherein determining the end condition includes determining whether the computed patient effort passes through a threshold value with a positive slope.

18. The system of claim 15 , wherein initiating the ventilation cycle includes determining an onset condition, and triggering the ventilation cycle based at least in part on the onset condition.

19. The system of claim 18 , wherein the computed patient effort is a function of a derivative of actual patient effort, and wherein determining the onset condition includes determining whether the computed patient effort passes through a threshold value with a negative slope.

20. 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 net flow 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, a second value related to the net flow and a third value related to patient effort to provide a prediction of patient effort;

update an interim value based at least in part on the prediction of patient effort, wherein the interim value is one of a covariance matrix and a parameter vector;

calculate a computed patient effort based at least in part on the interim value; and

initiate a ventilation cycle based at least in part on the computed patient effort.

21. The ventilator as in claim 20 wherein the initiate a ventilation cycle comprises transitioning from exhalation to inhalation.

22. The ventilator as in claim 20 wherein the initiate a ventilation cycle comprises transitioning from inhalation to exhalation.