Systems and methods for respiratory effort detection utilizing signal distortion

1. A method for triggering inhalation during spontaneous or assisted ventilation of a patient on a mechanical ventilator, comprising:

monitoring, during an exhalation phase, a physiologic parameter signal of a patient receiving ventilation on a mechanical ventilator;

tracking a distortion indicator in the physiologic parameter signal, wherein the distortion indicator comprises a deviation of a residual value of the physiologic parameter signal from a residual base;

applying a sensitivity check to the distortion indicator;

detecting a patient inhalation effort in response to the sensitivity check; and

triggering an inhalation by the mechanical ventilator in response to the detected patient inhalation effort.

2. The method of claim 1 , wherein applying the sensitivity check comprises comparing the distortion indicator to a sensitivity threshold.

3. The method of claim 1 , further comprising receiving measurements of a physiologic parameter from one or more sensors coupled to the ventilator, the measurements forming the physiologic parameter signal.

4. The method of claim 3 , wherein the physiologic parameter comprises flow or pressure.

5. The method of claim 3 , wherein the one or more sensors are non-invasive.

6. The method of claim 1 , further comprising, after applying the sensitivity check, setting a flag indicating a presence of the detected patient inhalation effort.

7. The method of claim 1 , further comprising displaying the distortion indicator versus time on a graph with a pressure or flow waveform.

8. The method of claim 1 , wherein the residual value and residual base are dynamically updated during exhalation.

9. The method of claim 1 , wherein detecting the patient inhalation effort occurs before an exhalation flow or pressure has crossed a trigger baseline.

10. The method of claim 1 , further comprising:

further monitoring the physiologic parameter signal during an inhalation phase;

applying a second sensitivity check to the distortion indicator;

detecting a patient exhalation effort in response to the second sensitivity check; and

cycling the mechanical ventilator to exhalation in response to the detected patient exhalation effort.

11. The method of claim 1 , wherein the residual value is a difference between a current value of the physiologic parameter signal and an averaged value of a defined number of recent values of the physiologic parameter signal.

12. The method of claim 1 , wherein the residual base is equal to a prior residual value.

13. A method for triggering inhalation during spontaneous or assisted ventilation of a patient on a mechanical ventilator, comprising:

monitoring, during an exhalation phase, a flow or pressure signal of a patient receiving ventilation on a mechanical ventilator;

tracking a distortion indicator in the flow or pressure signal, wherein the distortion indicator comprises a deviation of a residual value of the flow or pressure signal from a residual base;

dynamically updating the distortion indicator during the exhalation phase;

detecting, from the distortion indicator, an occurrence of a distortion indicative of an inhalation effort before the flow or pressure signal has crossed a trigger baseline; and

triggering an inhalation by the mechanical ventilator as a result of the detected occurrence of the distortion.

14. The method of claim 13 , further comprising displaying the distortion indicator on a display screen of the mechanical ventilator.

15. The method of claim 13 , wherein the residual value is a difference between a current value of the flow or pressure signal and an averaged value of a defined number of recent values of the flow or pressure signal.

16. The method of claim 13 , wherein the residual base is equal to a prior residual value.

17. A method for triggering inspiration during spontaneous or assisted ventilation of a patient on a ventilator, comprising:

monitoring, from one or more non-invasive sensors during exhalation, a physiological parameter signal of a patient receiving ventilation from a ventilator;

determining, by a microprocessor, a first residual value and a signal-to-noise ratio of the physiological parameter signal;

determining, by the microprocessor, that the signal-to-noise ratio exceeds a noise threshold;

based on the signal-to-noise ratio exceeding the noise threshold, setting, by the microprocessor, a residual base equal to the first residual value;

determining, by the microprocessor, a second residual value of the physiological parameter signal;

determining, by the microprocessor, that a deviation between the second residual value and the residual base satisfies a trigger condition;

detecting, in response to the satisfied trigger condition, a patient effort to inhale; and

triggering inspiration in response to the detection of the patient effort.

18. The method of claim 17 , wherein the trigger condition comprises a sensitivity threshold.

19. The method of claim 17 , wherein the first residual value and the second residual value occur within an exhalation phase of a breath.