Side-stream respiratory gas monitoring system and method

• US 8,459,261 B2
• Filed: 11/16/2006
• Issued: 06/11/2013
• Est. Priority Date: 11/16/2005
• Status: Active Grant

• Current Assignee: TreyMed, Inc.
• Original Assignee: TreyMed, Inc.
• Inventors: Ricciardelli, Robert H., Marking, Michael J.
• Primary Examiner(s): Dixon, Annette
• Application Number:
  US11/560,462
• Publication Number:
  US 20070107728A1
• Time in Patent Office: 2,399 Days
• Field of Search: 128/200.24, 128/203.12, 128/203.17, 128/203.26, 128/203.27, 128/204.18, 128/204.21, 128/204.23, 600/504, 600/486, 600/526, 600/529, 600/532, 600/538, 73/232, 422/84, 702/45, 702/53, 702/66, 702/67, 702/100, 702/104, 702/189
• US Class Current: 128/204.23
• CPC Class Codes: A61B 2560/0247 for compensation or correction of the measured physiological value
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take 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 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

A side-stream respiration monitoring system includes a sensor, a monitor, and a display. The sensor is constructed to engage respiration flows having a variable flow amounts and acquire a respiration sample from the flow. The monitor is connected to the sensor and configured to determine the amount of respiration flow as well as the amount of several constituents of the respiration flow such as oxygen, carbon dioxide, water, and nitrous oxide. The monitor is also configured to adjust the determined values for ambient environment variations and is self-calibrating with respect to the ambient conditions. The monitor temporally aligns the acquired data to account for dead-space respiration events and physiological respiration modifications such as cardiac events. Information generated by the monitor is communicated to an operator via a display configured to display the real-time respiration performance.

Claims

1. A side-stream respiration monitoring system comprising:

a flow sensor constructed to be disposed in a respiration flow path; and

a controller connected to the flow sensor and configured to

1) determine a respiration flow value through the respiration flow path and at least a portion of a composition of the respiration flow on a breath-by-breath basis that includes pulsatile effect respiration data; and

2) temporally associate in a time-domain each of the determined respiration flow value and the determined portion of the composition to account for at least two of flow path resistances, dead-space volumes, and flow composition for approximately each breath.

2. The system of claim 1 wherein the portion of the composition includes at least one of a concentration of oxygen and a concentration of carbon dioxide.

3. The system of claim 2 wherein the concentration of oxygen and the concentration of carbon dioxide is determined for each inspiration and expiration.

4. The system of claim 1 wherein the respiration flow value is pressure based.

5. The system of claim 1 wherein the controller further comprises an analyzer connected to the controller and configured to automatically adjust operation of the controller in response to ambient conditions.

6. The system of claim 5 wherein the analyzer includes a carbon dioxide sensor that is stable for gain and an oxygen sensor that is stable for offset.

7. The system of claim 1 further comprising a display configured to output the temporally associated respiration flow value and the portion of the composition on a common ordinate and abscissa.

8. The system of claim 7 wherein the controller offsets an ordinate scale of an oxygen value by an inspired oxygen value such that the output of the oxygen value is generally a mirror image of a carbon dioxide value.

9. The system of claim 7 wherein the controller calculates and inverses an oxygen deficit from the composition of the flow such that the output of the oxygen value is generally a mirror image of a carbon dioxide value.

10. The system of claim 1 wherein the controller includes a first input for fluidly connecting with the sensor and a second input for fluidly connecting the controller to a gas source.

11. The system of claim 10 wherein the gas source is one of another flow sensor, a Douglas gas, and a gas bottle.

12. The system of claim 1 further comprising a physiological detector connected to the controller for receiving a physiological signal, the controller configured to temporally associate physiological signal with the respiration flow value and the portion of the composition.

13. The system of claim 12 wherein the physiological detector is a heart beat monitor.

14. The system of claim 1 further comprising an adapter for engaging the flow sensor and configured to allow a first portion of a respiration flow to bypass the flow sensor so that the first portion of the respiration flow is a multiple of the flow through the flow sensor.

15. A respiration monitoring system comprising:

a flow sensor constructed to detect a respiration flow and acquire a side-stream sample of the flow;

an analyzer constructed to determine an amount of a gas carried on the respiration flow; and

a controller configured to automatically calibrate the analyzer to address a first deviation of a first sensor and address a second deviation that is different than the first deviation for a second sensor.

16. The system of claim 15 wherein the gas includes any gas from the group of carbon dioxide, oxygen, and nitrous oxide.

17. The system of claim 15 wherein the controller is configured to monitor an ambient condition and adjust operation of the analyzer in response to the ambient condition.

18. The system of claim 17 wherein the ambient condition is at least one of ambient oxygen content, ambient carbon dioxide content, ambient nitrous oxide content, ambient temperature, ambient air humidity, and barometric pressure.

19. The system of claim 15 wherein the controller is configured to repeat a calibration process periodically without interrupting operation of the system.

20. The system of claim 15 wherein the analyzer is configured to monitor oxygen and carbon dioxide levels in the side-stream flow and the controller is configured to associate the amount of oxygen and carbon dioxide to a volume of the respiration flow.

21. The system of claim 15 further comprising a housing constructed to enclose the controller and the analyzer and having the flow sensor fluidly connected therethrough and a display connectable to the housing.

22. The system of claim 15 wherein the controller is configured to adjust for dead-space associated with an aspiration flow path.

23. The system of claim 15 wherein the system is configured to be hand carried.

24. A side-flow respiration monitoring system comprising:

a sensor for detecting a respiration flow and acquiring a sample of the respiration flow;

a monitor connected to the sensor for determining an amount of oxygen and an amount of carbon dioxide in the respiration flow on approximately a breath-by-breath basis wherein the monitor is constructed to adjust the determined amounts of oxygen and carbon dioxide for a dead-space associated with an aspiration path; and

a display connected to the monitor for displaying information associated with the amount of oxygen and carbon dioxide on a common plot.

25. The system of claim 24 wherein the monitor is configured to determine a respiration flow value from a pressure differential detected by the sensor.

26. The system of claim 24 wherein the monitor includes an oxygen sensor, a pressure sensor, and a carbon dioxide sensor.

27. The system of claim 24 further comprising a detector attached to the monitor to acquire a heart rate signal, the monitor configured to align the heart rate signal, the respiration flow, amount of oxygen, and amount of carbon dioxide.

28. The system of claim 24 further comprising an adapter for connecting to the sensor for reducing a flow pressure by a multiple of a flow pressure of the sensor.

29. The system of claim 24 wherein the monitor is constructed to determine an ambient condition and adjust the displayed information in response to the ambient condition.

30. The system of claim 29 further comprising a timer configured to instruct the monitor to periodically determine the ambient condition.

31. The system of claim 24 wherein the monitor is configured to calculate a physiologic mirror information and communicate the physiologic mirror information to the display.

32. The system of claim 24 wherein the monitor is configured to determine a respiratory quotient (RQ) from the amount of oxygen and the amount of carbon dioxide in the respiration flow and communicate the RQ to the display.

33. The system of claim 32 wherein the monitor adjusts one of the determined amount of oxygen and the determined amount of carbon dioxide by a comparison of the RQ to the other of the determined amount of oxygen and the determined amount of carbon dioxide.

34. A method of monitoring respiration information comprising the steps of:

measuring a patient flow and a patient pressure;

acquiring a side-stream breath sample;

determining a flow of the side-stream breath sample, a concentration of oxygen, and a concentration of carbon dioxide in the acquired side-stream breath sample for all the measured and acquired respiration information of the side-stream breath sample including non-diaphragmatic respiration information; and

temporally aligning in a time domain the determined flow with the determined concentrations of oxygen and carbon dioxide with respect to their occurrence in the acquired side-stream breath sample on approximately a breath-by-breath basis.

35. The method of claim 34 further comprising displaying the temporally aligned flow and concentrations of oxygen and carbon dioxide on a common plot for an acquired breath sample.

36. The method of claim 34 wherein the step of determining the flow of the side-stream breath sample further comprises adjusting for a dead-space of an aspiration flow.

37. The method of claim 34 wherein the step of determining the concentrations of oxygen and carbon dioxide in the side-stream breath sample comprises adjusting at least one of a value of the concentration of oxygen and a value of the concentration of carbon dioxide for a respective concentration oxygen and carbon dioxide present in an inspiration source.

38. The method of claim 34 further comprising acquiring a heart rate and temporally associating the heart rate and the determined flow and the determined concentration of oxygen and carbon dioxide.

39. The method of claim 34 further comprising determining and displaying a concentration of nitrous oxide present in the side-stream breath sample.

40. The method of claim 34 further comprising determining an amount of patient nitrous oxide exchange.

41. The method of claim 34 further comprising determining a respiratory quotient.

42. The method of claim 41 further comprising adjusting one of the determined concentrations of oxygen and carbon dioxide based on the respiratory quotient and the other of the determined concentrations of oxygen and carbon dioxide.

43. The method of claim 34 wherein the step of acquiring a side-stream breath sample includes monitoring a first portion of a breath flow and allowing non-monitored passage of a second portion of the breath flow wherein the second portion is a multiple of the first portion of the breath flow.

44. The method of claim 34 further comprising connecting a sensor for the acquiring step to a monitor for the determining steps to a display for outputting the temporally aligned flow and concentrations of oxygen and carbon dioxide.

45. The method of claim 34 further comprising connecting any two of a sensor, a monitor, and a display via a serial port connection, serial bus connection, an expansion port connection, a slot connection, a lumen tube, and a wireless communication interface.

46. The method of claim 34 further comprising providing a first sensor for a very small patient, a second sensor for a small patient, a third sensor for an adult patient, and a bypass adapter to engage the third sensor for elevated respiration flows.

53. The analyzer of claim 41 wherein the analyzer varies the rate of the mimicked breath cycle.

47. A breath-by-breath analyzer comprising:

a sensor constructed to engage a respiration flow;

an analyzer connected to the sensor and configured to determine a pressure and at least a portion of a composition of the respiration flow;

an adapter configured to engage the sensor wherein a first portion of the respiration flow passes through the adapter and is directed to the sensor and a second portion of the respiration flow that travels in the same direction as the first portion of the respiration flow passes through the adapter and bypasses the sensor and the analyzer; and

wherein the second portion of the respiration flow is a multiple of the first portion of the respiration flow.

48. The analyzer of claim 47 wherein the analyzer includes an oxygen sensor and a carbon dioxide sensor and is configured to determine respective amounts of oxygen and carbon dioxide in an exhalation.

49. The analyzer of claim 48 wherein the analyzer is configured to determine a respiratory quotient from the determined amounts of oxygen and carbon dioxide.

50. The analyzer of claim 49 wherein the analyzer determines a respiratory quotient on a breath-by-breath basis.

51. The analyzer of claim 49 wherein the analyzer compares the respiratory quotient to one of the determined amounts of oxygen and carbon dioxide and adjusts the other of the determined amount of oxygen and carbon dioxide based on the comparison.

52. The analyzer of claim 49 wherein the analyzer automatically calibrates by mimicking a breath cycle.

54. The analyzer of claim 49 wherein the analyzer is constructed to perform an operation verification based on the respiratory quotient on a breath-by-breath basis.

55. The analyzer of claim 47 further comprising a nitrous oxide sensor configured to determine an amount of nitrous oxide in a breath.

56. The analyzer of claim 47 further comprising a cardiac detector and a display, the analyzer configured to generate real-time aligned data associated with the respiration flow and the cardiac detector to generate an output on the display.

57. The analyzer of claim 47 wherein the analyzer is configured to monitor an ambient condition and adjust data associated with the portion of the composition of the respiration flow to account for the ambient condition.

58. The analyzer of claim 47 further comprising a container constructed to retain an exhalation for analysis after the exhalation and the analyzer includes a first input for connecting to the sensor and another input for fluidly connecting to the container.

59. The analyzer of claim 58 wherein the container is constructed to receive a gas having a known respiratory quotient and the analyzer is constructed to autocalibrate at least one of an oxygen sensor and a carbon dioxide sensor at least in part based on the known respiratory quotient.

60. A respiration monitoring system comprising:

an oxygen sensor constructed to detect an oxygen concentration;

a carbon dioxide sensor constructed to detect a carbon dioxide concentration;

a first input constructed to fluidly connect a first source of a breathable gas mixture to the oxygen and carbon dioxide sensors; and

a second input that is fluidly isolated from the first input and is constructed to fluidly connect a second source of a breathable gas mixture to the oxygen and carbon dioxide sensors.

61. The system of claim 60 further comprising a sensor connected to the first input and the first gas source is a patient respiration through the sensor.

62. The system of claim 61 wherein the second gas source is one of another patient respiration through another sensor, a Douglas bag, a container having a known mixture of gas, and an oxygen source.

63. The system of claim 62 wherein the container has a gas with a known respiratory quotient (RQ) and the monitoring system calculates an RQ and performs a performance check of one of the oxygen sensor and the carbon dioxide sensor based on the calculated RQ.

64. The system of claim 63 wherein the monitoring system adjusts operation of one of the oxygen sensor and the carbon dioxide sensor based on the performance check.

65. A respiration monitoring device comprising:

at least one valve;

a pump connected to the valve;

an oxygen sensor and a carbon dioxide sensor; and

a control configured to control operation of the valve and the pump for communicating a gas to each of the oxygen sensor and the carbon dioxide sensor to mimic a breath flow and a breath composition.

66. The device of claim 65 further comprising a housing configured to enclose the valve, the pump, and the control.

67. The device of claim 65 wherein the gas is provided from at least one of a Douglas bag and a gas cylinder.

68. The device of claim 65 wherein the control is configured to calculate an RQ value from a first signal generated by the oxygen sensor and a second signal generated by the carbon dioxide sensor.

69. The device of claim 68 wherein the control is configured to modify one of a value calculated from the first signal and a value calculated from the second signal based on a comparison of the RQ value and the other of the value calculated from the first signal and the value calculated from the second signal.

70. The device of claim 65 further comprising a first input constructed to fluidly connect a first gas source to the valve and a second input to fluidly connect a second gas source to the valve.

71. A physiologic monitor controller comprising:

an input configured to receive a physiologic signal; and

a correction protocol configured to determine an output by adjusting a value of the input in an amplitude domain and a time domain.

72. The controller of claim 71 wherein the amplitude domain is at least one of concentration, temperature, pressure, and flow.

73. The controller of claim 72 wherein the concentration is at least one of oxygen concentration, carbon dioxide, nitrous oxide, and water vapor concentration.

74. The controller of claim 71 wherein the correction protocol is determined in part by a type of sensor.

75. The controller of claim 74 wherein the type of sensor is a galvanic-type oxygen sensor and the correction protocol performs a first correction on a response time characteristic and second correction different than the first correction on another response time characteristic.

76. The controller of claim 75 wherein the response time characteristic is different than the another response time characteristic.