Non-invasive method and apparatus for optimizing the respiration of atelectatic lungs

• US 20070068528A1
• Filed: 09/22/2006
• Published: 03/29/2007
• Est. Priority Date: 03/26/2004
• Status: Active Grant

• Current Assignee: Salvia medical GmbH & Co. KG
• Original Assignee: Stephan Bohm
• Inventors: Bohm, Stephan, Tusman, Gerardo
• Granted Patent: US 9,173,595 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• 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 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/202 partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)

Abstract

The invention concerns a method and apparatus for determining the status of a ventilated lung. For determining the status of a lung ventilated, which enables in real time optimal ventilatory settings for a recruitment maneuver of an ailing lung, the invention comprises a sensor for measuring a gas concentration in the expired gas during a single breath, an analog to digital converter for obtaining data samples of said gas concentration in the time domain, means for selecting a plurality of data samples, means for calculating a mean tracing value being sensitive to changes of alveolar dead space based on said samples, and a data processor which detects during a change of the airway of the ventilator from the resulting course of calculated mean tracing values the peak inspiratory pressure at which alveolar opening or lung overdistension occurs and/or the PEEP at which lung open condition or alveolar closing occurs.

Claims

1. Method for determining the status of a lung ventilated by an artificial ventilator, comprising the steps of:

a) obtaining data samples of a gas concentration of the expired gas over a single breath,

b) selecting a plurality of data samples from said obtained data samples,

c) calculating a mean tracing value being sensitive to changes of alveolar dead space on the basis of said selected data samples,

d) repeating steps a), b) and c) for obtaining a plurality of mean tracing values, and

e) changing the peak inspiratory pressure and the positive end expiratory pressure of the artificial ventilator, wherein from the observation of the resulting course of the plurality of calculated mean tracing values the peak inspiratory pressure at which alveolar opening or lung overdistension and/or the positive end expiratory pressure at which lung open condition or alveolar closing occurs are detected.

2. Method according to claim 1, wherein the gas concentration represents the CO₂ concentration.

3. Method according to claim 2, wherein the data samples according to step a) are obtained in the time domain.

4. Method according to claim 3, wherein the obtained data samples are converted from the time domain into the volumetric domain.

5. Method according to claim 2, wherein a first mean tracing value is represented by the endtidal mean slope of the CO₂ concentration in the expired gas during a single breath.

6. Method according to claim 5, wherein starting from alveolar closing the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein an alveolar opening of the lung is detected, if the resulting course of the plurality of determined first mean tracing values reaches a minimum.

7. Method according to claim 5, wherein starting from alveolar opening the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein a lung overdistension is detected, if the positive gradient of the resulting course of the plurality of determined first mean tracing values reaches a maximum.

8. Method according to claim 5, wherein starting from lung overdistension the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an open lung condition is detected, if the resulting course of the plurality of determined first mean tracing values reaches a minimum.

9. Method according to claim 5, wherein starting from an open lung condition the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an alveolar closing is detected, if the positive gradient of the resulting course of the plurality of determined first mean tracing values reaches a maximum.

10. Method according to claim 2, wherein a second mean tracing value is represented by the steepest mean slope of the CO₂ concentration in the expired gas during a single breath.

11. Method according to claim 10, wherein starting from alveolar closing the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein an alveolar opening of the lung is detected, if the resulting course of the plurality of determined second mean tracing values reaches a maximum.

12. Method according to claim 10, wherein starting from alveolar opening the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein a lung overdistension is detected, if the negative gradient of the resulting course of the plurality of determined second mean tracing values reaches a minimum.

13. Method according to claim 10, wherein starting from lung overdistension the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an open lung condition is detected, if the resulting course of the plurality of determined second mean tracing values reaches a maximum.

14. Method according to claim 10, wherein starting from an open lung condition the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an alveolar closing is detected, if the negative gradient of the resulting course of the plurality of determined second mean tracing values reaches a minimum.

15. Method according to claim 2, wherein a third mean tracing value is represented by the angle between the endtidal mean slope and the steepest mean slope of the CO₂ concentration in the expired gas during a single breath.

16. Method according to claim 15, wherein starting from alveolar closing the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein an alveolar opening of the lung is detected, if the resulting course of the plurality of determined third mean tracing values reaches a minimum.

17. Method according to claim 15, wherein starting from alveolar opening the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein a lung overdistension is detected, if the positive gradient of the resulting course of the plurality of determined third mean tracing values reaches a maximum.

18. Method according to claim 15, wherein starting from lung overdistension the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an open lung condition is detected, if the resulting course of the plurality of determined third mean tracing values reaches a minimum.

19. Method according to claim 15, wherein starting from an open lung condition the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an alveolar closing is detected, if the positive gradient of the resulting course of the plurality of determined third mean tracing values reaches a maximum.

20. Method according to claim 2, wherein a plurality of different types of mean tracing values are calculated in parallel and wherein from the resulting course of the plurality of different types of mean tracing values the peak inspiratory pressure at which alveolar opening or lung overdistension and/or the positive end expiratory pressure at which lung open condition or alveolar closing occurs are detected.

21. Method according to claim 2, wherein during a recruitment maneuver of the lung the peak inspiratory pressure is set above the peak inspiratory pressure at which alveolar opening has been detected and the positive end-expiratory pressure is set above the positive end expiratory pressure at which alveolar closing has been detected.

22. Apparatus for determining the status of a lung ventilated by an artificial ventilator, comprising:

a sensor for measuring a gas concentration in the expired gas during a single breath,

an analog to digital converter for obtaining data samples of said gas concentration of the expired gas over a single breath in the time domain,

means for selecting a plurality of data samples from said obtained data samples,

means for calculating a mean tracing value being sensitive to changes of alveolar dead space on the basis of said selected data samples, and

a data processor which detects during a change of the airway pressure of the artificial ventilator from the resulting course of a plurality of calculated mean tracing values the peak inspiratory pressure at which alveolar opening or lung overdistension occurs and/or the positive end expiratory pressure at which lung open condition or alveolar closing occurs.

23. Apparatus according to claim 22, wherein the gas concentration represents the CO₂ concentration.

24. Apparatus according to claim 23, wherein the analog to digital converter converts the data samples in the time domain.

25. Apparatus according to claim 23, further comprising a means for assessing a volumetric rate of the expired gas and a means for converting the obtained data samples from the time domain to the volumetric domain.

26. Apparatus according to claim 23, wherein a first mean tracing value is represented by the endtidal mean slope of the CO₂ concentration in the expired gas during a single breath.

27. Apparatus according to claim 26, wherein starting from alveolar closing the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein an alveolar opening of the lung is detected, if the resulting course of the plurality of determined first mean tracing values reaches a minimum.

28. Apparatus according to claim 26, wherein starting from alveolar opening the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein a lung overdistension is detected, if the positive gradient of the resulting course of the plurality of determined first mean tracing values reaches a maximum.

29. Apparatus according to claim 26, wherein starting from lung overdistension the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an open lung condition is detected, if the resulting course of the plurality of determined first mean tracing values reaches a minimum.

30. Apparatus according to claim 26, wherein starting from an open lung condition the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an alveolar closing is detected, if the positive gradient of the resulting course of the plurality of determined first mean tracing values reaches a maximum.

31. Apparatus according to claim 23, wherein a second mean tracing value is represented by the steepest mean slope of the CO₂ concentration in the expired gas during a single breath.

32. Apparatus according to claim 31, wherein starting from alveolar closing the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein an alveolar opening of the lung is detected, if the resulting course of the plurality of determined second mean tracing values reaches a maximum.

33. Apparatus according to claim 31, wherein starting from alveolar opening the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein a lung overdistension is detected, if the negative gradient of the resulting course of the plurality of determined second mean tracing values reaches a minimum.

34. Apparatus according to claim 31, wherein starting from lung overdistension the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an open lung condition is detected, if the resulting course of the plurality of determined second mean tracing values reaches a maximum.

35. Apparatus according to claim 31, wherein starting from an open lung condition the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an alveolar closing is detected, if the negative gradient of the resulting course of the plurality of determined second mean tracing values reaches a minimum.

36. Apparatus according to claim 23, wherein a third mean tracing value is represented by the angle between the endtidal mean slope and the steepest mean slope of the CO₂ concentration in the expired gas during a single breath.

37. Apparatus according to claim 36, wherein starting from alveolar closing the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein an alveolar opening of the lung is detected, if the resulting course of the plurality of determined third mean tracing values reaches a minimum.

38. Apparatus according to claim 36, wherein starting from alveolar opening the peak inspiratory pressure of the artificial ventilator is increased stepwise breath by breath and wherein a lung overdistension is detected, if the positive gradient of the resulting course of the plurality of determined third mean tracing values reaches a maximum.

39. Apparatus according to claim 36, wherein starting from lung overdistension the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an open lung condition is detected, if the resulting course of the plurality of determined third mean tracing values reaches a minimum.

40. Apparatus according to claim 36, wherein starting from an open lung condition the positive end expiratory pressure of the artificial ventilator is decreased stepwise breath by breath and wherein an alveolar closing is detected, if the positive gradient of the resulting course of the plurality of determined third mean tracing values reaches a maximum.

41. Apparatus according to claim 23, wherein a plurality of different types of mean tracing values are calculated in parallel and wherein from the resulting course of the plurality of different types of mean tracing values the peak inspiratory pressure at which alveolar opening or lung overdistension and/or the positive end expiratory pressure at which lung open condition or alveolar closing occurs are detected.

42. Apparatus according to claim 23, wherein during a recruitment maneuver of the lung the peak inspiratory pressure is set above the peak inspiratory pressure at which alveolar opening has been detected and the positive end-expiratory pressure is set above the positive end expiratory pressure at which alveolar closing has been detected.