System for measuring respiratory function

• US 20020120207A1
• Filed: 09/10/2001
• Published: 08/29/2002
• Est. Priority Date: 04/23/1999
• Status: Active Grant

• Current Assignee: Trustees of Tufts College
• Original Assignee: Trustees of Tufts College
• Inventors: Hoffman, Andrew
• Granted Patent: US 6,723,055 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/0878 using temperature sensing means
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise
• CPC Class Codes: A61D 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

The present invention relates to a system for measuring respiratory function of living organisms. More particularly, signals indicative of the change in lung volume, defined as active and passive work, required to breathe and the airflow through the respiratory system of the living organism are obtained and processed as waveforms to provide a signal indicative of the respiratory restriction. The methods of the present invention measure clinical forms of airway obstruction, airway reactivity and lung volume and may be used to continuously or intermittently monitor patients with compromised respiratory function. In a preferred embodiment, a head-out, breath in respiratory plethysmograph system provides the signals indicative of change in lung volume as related to pressure changes in a chamber. Further, flowmetric variables are generated that provide a characterization of airway obstructions.

Claims

1. A method for measuring airway reactivity of a living organism, comprising the steps:

obtaining a first input signal from a first sensor indicative of a change in lung volume during breathing by said living organism;

obtaining a second input signal from a second sensor indicative of airflow through the respiratory system of said living organism during the change in lung volume; and

processing said first input signal and said second input signal to calculate a third signal indicative of respiratory restriction of said living organism.

2. The method according to claim 1, wherein the processing step comprises the step of comparing said first input signal to said second input signal.

3. The method according to claim 2, wherein the step of comparing said first and second input signals comprises analyzing the phase and magnitude differences between said first and second signals in the same time domain.

4. The method according to claim 3, wherein the step of comparing said first and second input signals further comprises the step of subtracting said second input signal from said first input signal.

5. The method according to claim 1, further comprising of obtaining the first input signal through use of respiratory induction plethysmography.

6. The method according to claim 1, further comprising of obtaining the first input signal through use of a piezoelectric device.

7. The method according to claim 1, further comprising of obtaining the first input signal through use of impedance plethysmography.

8. The method according to claim 1, further comprising of obtaining the first input signal through use of at least one of a head out, breath in plethysmograph, an optoelectronic plethysmograph and a fiber optic respiration plethysmograph.

9. The method according to claim 1, further comprising of obtaining the second input signal through use of a pneumotachographic measurement device.

10. The method according to claim 1, further comprising of obtaining the second input signal through use of an ultrasonic device.

11. The method according to claim 1, further comprising of obtaining the second input signal through use of a thermistor.

12. The method according to claim 1, further comprising of obtaining the second input signal through use of a breath-sound intensity device.

13. The method according to claim 1, further comprising the step of calibrating first input signal.

14. The variables associated with the expiratory phase of breathing method according to claim 1, further comprising the step of calibrating second input signal.

15. The method according to claim 1, further comprising the step of displaying said first input signal and said first second input signal as digital waveforms.

16. The method according to claim 1, further comprising the steps of:

obtaining a signal through respiratory inductance plethysmography of a chest of said living organism;

obtaining a signal through respiratory inductance plethysmography of an abdomen of said living organism;

summing said chest signal and said abdomen signal to form said first input signal;

converting said first input signal from an analog signal to a digital signal;

taking the derivative of said digital first input signal;

converting said second signal from an analog to a digital signal; and

subtracting said second input signal from said digital derivative of first input signal to obtain said third signal.

17. The method according to claim 16, wherein the steps of converting an input signal from analog to digital signal, taking the derivative of, converting signal from an analog to digital signal and subtracting said second input signal from digital derivative of first input signal, uses at least one of the signal of the chest, the signal of the abdomen or the;

first input signal indicative of the sum of the chest and abdomen signal.

18. The method according to claim 1, further comprising the step of administering a medication to the living organism to alter the respiratory function.

19. The method according to claim 18, further comprising of administering a bronchoconstrictor medication.

20. A method for measuring clinical airway obstruction of a living organism comprising the steps of:

obtaining a first input signal from a first sensor indicative of a change in lung volume during breathing by said living organism;

obtaining a second input signal from a second sensor indicative of airflow through the respiratory system of said living organism during the change in lung volume; and

processing said first input signal and said second input signal to calculate a third signal indicative of respiration restriction of said living organism.

21. The method according to claim 20, wherein the processing step comprises the step of comparing said first input signal to said second input signal.

22. The method according to claim 21, wherein the step of comparing said first and second input signals comprises analyzing phase and magnitude differences between said first and second signals in the same time domain.

23. The method according to claim 22, wherein the step of comparing said first and second input signals further comprises the step of subtracting said second input signal from said first input signal.

24. The method according to claim 20, further comprising of obtaining the first input signal through use of at least one of respiratory induction plethysmography;

head out, breath in plethysmograph, an optoelectronic plethysmograph and a fiber optic respiration plethysmograph.

25. The method according to claim 20, further comprising of obtaining the first input signal through use of a piezoelectric device.

26. The method according to claim 20, further comprising of obtaining the first input signal through use of impedance plethysmography.

27. The method according to claim 20, further comprising of obtaining the second input signal through use of a pneumotachographic measurement device.

28. The method according to claim 20, further comprising of obtaining the second input signal through use of an ultrasonic device.

29. The method according to claim 20, further comprising of obtaining the second input signal through use of a thermistor.

30. The method according to claim 20, further comprising of obtaining the second input signal through use of a breath-sound intensity device.

31. The method according to claim 20, further comprising the step of calibrating first input signal.

32. The method according to claim 20, further comprising the steps of:

obtaining a signal through respiratory inductance plethysmography of a chest of said living organism;

obtaining a signal through respiratory inductance plethysmography of an abdomen of said living organism;

summing said chest signal and said abdomen signal to form said first input signal;

converting said first input signal from an analog signal to a digital signal;

displaying said first input signal and said first second input signal as digital waveforms.

taking the derivative of said digital first input signal;

converting said second signal from an analog to a digital signal; and

subtracting said second input signal from said digital derivative of first input signal to obtain said third signal.

33. The method according to claim 20, further comprising the step of administering a medication to the living organism to alter the respiratory function.

34. The method according to claim 20, further comprising of administering a bronchodilators medication.

36. The method according to claim 35, wherein the processing step comprises the step of comparing said first input signal to said second input signal.

37. The method according to claim 36, wherein the step of comparing said first and second input signals comprises analyzing phase and magnitude differences between said first and second signals in the same time domain.

38. The method according to claim 37, wherein the step of comparing said first and second input signals further comprises the step of subtracting said second input signal from said first input signal.

39. The method according to claim 35, further comprising of obtaining the first input signal through use of at least one of respiratory induction plethysmography;

head out, breath in plethysmograph, an optoelectronic plethysmograph and a fiber optic respiration plethysmograph.

40. The method according to claim 35, further comprising of obtaining the first input signal through use of a piezoelectric device.

41. The method according to claim 35, further comprising of obtaining the first input signal through use of impedance plethysmography.

42. The method according to claim 35, further comprising of obtaining the second input signal through use of a pneumotachographic measurement device.

43. The method according to claim 35, further comprising of obtaining the second input signal through use of an ultrasonic device.

44. The method according to claim 35, further comprising of obtaining the second input signal through use of a thermistor.

45. The method according to claim 35, further comprising of obtaining the second input signal through use of a breath-sound intensity device.

46. The method according to claim 35, further comprising the step of calibrating first input signal.

47. The method according to claim 35, further comprising the steps of:

obtaining a signal through respiratory inductance plethysmography of a chest of said living organism;

obtaining a signal through respiratory inductance plethysmography of an abdomen of said living organism;

summing said chest signal and said abdomen signal to form said first input signal;

converting said first input signal from an analog signal to a digital signal;

displaying said first input signal and said first second input signal as digital waveforms.

taking the derivative of said digital first input signal;

converting said second signal from an analog to a digital signal; and

subtracting said second input signal from said digital derivative of first input signal to obtain said third signal.

48. The method according to claim 35, further comprising the step of administering a medication to the living organism to alter the respiratory function.

49. The method according to claim 35, further comprising of administering a bronchodilators medication.

50. The method according to claim 35, wherein the plurality of signals indicative of respiratory restriction comprise at least one of functional residual capacity, airway resistance, peak and area differences during expiration, peak and area differences during inspiration and corrected values thereof.

51. The method according to claim 35, further comprising the steps of:

obtaining a first input signal indicative of a change in lung volume as related to a pressure change in a head out, breath in plethysmograph chamber;

converting said first input signal from an analog signal to a digital signal;

taking the derivative of said digital first input signal to generate a signal indicative of thoracic flow;

converting the second input signal from an analog to a digital signal;

taking the derivative of the second input signal to generate a signal indicative of nasal airflow; and

dynamically comparing the signals indicative of thoracic flow and nasal airflow.

35. A method for characterizing airway obstruction of a living organism, comprising the steps of:

obtaining a first input signal from a first sensor indicative of a change in lung volume as related to a pressure change in a chamber during breathing by said living organism;

obtaining a second input signal from a second sensor indicative of airflow through the respiratory system of said living organism during the change in lung volume; and

processing said first input signal and said second input signal to calculate a plurality of signals indicative of respiration restriction of said living organism.