Respiratory profile parameter determination method and apparatus

• US 6,099,481 A
• Filed: 11/03/1997
• Issued: 08/08/2000
• Est. Priority Date: 11/03/1997
• Status: Expired due to Term

• Current Assignee: RIC INVESTMENTS LLC (Respironics Incorporated)
• Original Assignee: NTC Technology, Inc. (Dixtal Medical, Inc.)
• Inventors: DelFavero, John R., Jaffe, Michael B., Gunneson, Paul B., Daniels, Rich H., Feldman, Barry J., Wigforss, Eric P.
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): ASTORINO, MICHAEL C
• Application Number:
  US08/963,394
• Time in Patent Office: 1,009 Days
• Field of Search: 600/528-541, 128/719, 128/661.1, 128/204.12-204.23
• US Class Current: 600/538
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/021 operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2230/202 partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)

Abstract

A method of sampling one or more respiratory profile characteristics and monitoring a variety of respiratory profile parameters. The sampled respiratory characteristics include respiratory flow rate, respiratory pressure, and partial pressure of at least one constituent of a patient'"'"'s respiration. The method detects patient breaths, determines whether each breath is a spontaneous breath or a ventilator-induced breath, and calculates various respiratory profile parameters based on the sampled measurements. The method displays the respiratory profile parameters in graphic and numeric forms. Preferably, the method allows a user to select the displayed respiratory profile parameters.

Claims

1. A method, implementable at least in part in a computer-useable code, for determining a plurality of respiratory profile characteristics, the method comprising:

measuring respiratory flow;

generating data representative of said measured respiratory flow;

detecting at least one patient breath based on said respiratory flow data;

employing the computer-useable code to convert said respiratory flow data from a time domain to a volume domain to calculate a plurality of respiratory volume parameters;

employing the computer-useable code to calculate a plurality of respiratory pressure parameters based at least in part on said respiratory flow data in said volume domain; and

employing the computer-useable code to calculate at least one respiratory mechanics parameter based on at least one of said plurality of respiratory volume parameters and at least one of said plurality of respiratory pressure parameters.

2. The method of claim 1, wherein said detecting said at least one patient breath comprises:

analyzing said plurality of respiratory data; and

comparing said respiratory flow data to an inspiratory flow threshold and an expiratory flow threshold.

3. The method of claim 1, further comprising characterizing said at least one patient breath as either a spontaneous breath or as a ventilator-induced breath.

4. The method of claim 3, wherein said characterizing said at least one patient breath is effected by use of the computer-useable code and includes comparing selected ones of said plurality of respiratory pressure parameters to each other.

5. The method of claim 1, wherein said employing the computer-useable code to convert said respiratory flow data from said time domain to said volume domain comprises rectangular integration.

6. The method of claim 1, wherein said employing the computer-useable code to convert said respiratory flow data from said time domain to said volume domain comprises trapazoidal integration.

7. The method of claim 1, wherein said plurality of respiratory volume parameters are selected from the group consisting of:

inspiratory volumes, expiratory volumes, mean inspiratory volumes, mean expiratory volumes, alveolar tidal volumes, expired carbon dioxide volumes, inhaled carbon dioxide volumes, minute ventilation volumes, alveolar minute ventilation volumes, minute volumes of carbon dioxide, and average tidal volumes.

8. The method of claim 1, wherein said plurality of respiratory flow rate parameters are selected from the group consisting of:

peak inspiratory flow, peak expiratory flow, mean inspiratory flow, and mean expiratory flow.

9. The method of claim 1, wherein said plurality of respiratory phase duration parameters are selected from the group consisting of:

inspiratory time, expiratory time, total breath time, respiratory rates, and ratio of inspiratory time to expiratory time.

10. The method of claim 1, wherein said plurality of respiratory pressure parameters are selected from the group consisting of:

mean airway pressure, mean inspiratory pressure, peak inspiratory pressure, positive end-expiratory pressure, plateau pressure, auto-PEEP, initial inspiratory pressure, and initial expiratory pressure.

11. The method of claim 10, further comprising employing the computer-useable code to characterize said at least one patient breath as either a spontaneous breath or as a ventilator-induced breath.

12. The method of claim 11, wherein said employing the computer-useable code to characterize said at least one patient breath includes employing the computer-useable code to compare selected ones of said plurality of respiratory pressure parameters to each other.

13. The method of claim 12, wherein, if the mean inspiratory pressure for said patient breath is less than or equal to positive end-expiratory pressure for said patient breath, said patient breath is characterized as a spontaneous breath.

14. The method of claim 12, wherein, if the peak inspiratory pressure for said patient breath less the positive end-expiratory pressure for said patient breath is lower than a ventilator pressure threshold, said patient breath is characterized as a spontaneous breath.

15. The method of claim 1, further comprising employing the computer-useable code to calculate a plurality of dead space parameters.

16. The method of claim 15, wherein said plurality of dead space parameters are selected from the group consisting of:

airway dead space, alveolar dead space, anatomic dead space, and physiologic dead space.

17. The method of claim 1, further comprising:

measuring carbon dioxide;

generating data representative of said measured carbon dioxide; and

employing the computer-useable code to calculate a plurality of carbon dioxide-related parameters.

18. The method of claim 17, wherein said plurality of carbon dioxide-related parameters are selected from the group consisting of:

total volume of carbon dioxide expired, minute volume of carbon dioxide, mixed expired carbon dioxide, end tidal partial pressure of carbon dioxide, and carbon dioxide inhaled.

19. The method of claim 1, wherein said at least one respiratory mechanics parameter is selected from the group consisting of:

dynamic compliance (C_dyn), static compliance (C_st), airway resistance during inspiration, airway resistance during expiration, compliance over the last twenty percent of a patient breath (C₂₀), (C₂₀ /C_dyn), ventilator work of breathing, and respiratory shallow breathing index.

20. A method, implementable in computer-useable code, for determining a plurality of respiratory profile characteristics, the method comprising:

measuring respiratory flow;

generating data representative of said measured respiratory flow;

detecting at least one patient breath based on said respiratory flow data;

employing the computer-useable code to convert said respiratory pressure data from a time domain to a volume domain to determine a plurality of respiratory volume parameters, a plurality of respiratory phase duration parameters, and a plurality of respiratory flow rate parameters;

employing the computer-useable code to calculate a plurality of respiratory pressure parameters based at least in part on said respiratory flow data in said volume domain; and

employing the computer-useable code to calculate at least one respiratory mechanics parameter based on at least one of said plurality of respiratory volume parameters and at least one of said plurality of respiratory pressure parameters.

21. The method of claim 20, wherein said employing the computer-useable code to detect said at least one patient breath comprises:

analyzing respiratory pressure data and respiratory volume data;

comparing said respiratory pressure data to an inspiratory pressure threshold and an expiratory pressure threshold; and

comparing said respiratory volume data to an inspiratory volume threshold and an expiratory volume threshold.

22. A method of displaying data of a plurality of respiratory profile parameters, comprising:

in response to a signal, displaying a numeric value of a partial pressure of arterial carbon dioxide, an indicator of arterial blood oxygen saturation, a pulse rate, a respiratory rate, a partial pressure of end tidal carbon dioxide, and data of at least one other selected one of the plurality of respiratory profile parameters.

23. The method of claim 22, wherein said data is indicative of a respiratory profile parameter selected from the group consisting of:

respiratory pressure parameters, respiratory phase duration parameters, respiratory flow rate parameters, respiratory volume parameters, carbon dioxide-related parameters, dead space parameters, and respiratory mechanics parameters.

24. The method of claim 22, further comprising displaying a graphical representation of a selected one of the plurality of respiratory profile parameters in response to said signal.

25. The method of claim 22, further comprising displaying a warning in response to said signal.

26. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a respiratory volume parameter.

27. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a respiratory pressure parameter.

28. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a respiratory flow parameter.

29. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a respiratory phase duration parameter.

30. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a respiratory mechanics parameter.

31. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a dead space parameter.

32. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of a minute volume parameter.

33. The method of claim 22, wherein said data of said at least one other selected one of the plurality of respiratory profile parameters is indicative of an alveolar minute volume parameter.

34. The method of claim 24, wherein said graphical representation comprises a capnogram.

35. The method of claim 24, wherein said graphical representation comprises a plethysmogram.

36. The method of claim 24, wherein said graphical representation comprises a flow waveform.

37. The method of claim 24, wherein said graphical representation comprises a pressure waveform.

38. The method of claim 24, wherein said graphical representation comprises a flow volume loop.

39. The method of claim 24, wherein said graphical representation comprises a pressure volume loop.

40. The method of claim 24, wherein said graphical representation comprises a bar graph representative of a recent history.

41. The method of claim 40, wherein said bar graph includes a series of bars, each representing a discrete time interval of said recent history.

42. The method of claim 41, wherein each of said discrete time intervals is equal.

43. The method of claim 40, wherein said recent history is from about twenty minutes to about twenty-four hours.

44. The method of claim 40, wherein said data of said selected one of the plurality of respiratory profile parameters comprises alveolar minute ventilation data.

45. The method of claim 40, wherein said data of said selected one of the plurality of respiratory profile parameters comprises carbon dioxide production data.

46. The method of claim 40, wherein said data of said selected one of the plurality of respiratory profile parameters comprises tidal volume data.

47. The method of claim 25, wherein said warning indicates that at least one of the plurality of respiratory profile parameters has exceeded or fallen below a set threshold.

48. The method of claim 47, wherein said data of at least one other of the plurality of respiratory profile parameters is indicative of a respiratory profile parameter selected from the group consisting of:

end tidal partial pressure of carbon dioxide, respiration rate, SpO₂, and pulse rate.

52. The method of claim 24, wherein said displaying said graphical representation comprises displaying a multi-component bar graph including a plurality of bars, selected ones of said bars each including a first component and a discrete second component adjacent said first component.

53. The method of claim 52, wherein said first component represents a portion of a breath effected by a mechanical ventilator.

54. The method of claim 52, wherein said second component represents a portion of a breath effected spontaneously by a patient.

49. A computer system which determines a plurality of respiratory profile characteristics, comprising:

a logic circuit for detecting a patient breath;

a logic circuit for converting said plurality of respiratory pressure data from a time domain to a volume domain to determine a plurality of respiratory volume parameters, a plurality of respiratory phase duration parameters, and a plurality of respiratory flow rate parameters;

a logic circuit for determining a plurality of respiratory pressure parameters;

a logic circuit for determining a plurality of carbon dioxide-related parameters; and

a logic circuit for determining a plurality of dead space parameters.

50. The computer according to claim 49, wherein said logic circuit for detecting a patient breath comprises:

a logic circuit for analyzing a plurality of respiratory pressure data and a plurality of respiratory volume data;

a logic circuit for comparing said respiratory pressure data to an inspiratory pressure threshold and an expiratory pressure threshold; and

a logic circuit for comparing said respiratory volume data to an inspiratory volume threshold and an expiratory volume threshold.

51. The computer according to 49, further comprising a logic circuit for determining a plurality of respiratory mechanics parameters.