Arrangement and method for detecting spontaneous respiratory effort of a patient

• US 7,422,015 B2
• Filed: 11/22/2005
• Issued: 09/09/2008
• Est. Priority Date: 11/22/2005
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Tham, Robert Q., Bathe, Duncan P. L., Delisle, Matt S.
• Primary Examiner(s): Douglas; Steven O
• Application Number:
  US11/285,121
• Publication Number:
  US 20070113851A1
• Time in Patent Office: 1,022 Days
• Field of Search: 128/207.18, 128/203.22, 128/204.18, 128/912, 128/204.23, 128/204.26, 128/206.11, 128/207.17
• US Class Current: 128/207.18
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/0826 Detecting or evaluating apnoea events A61B5/4818 takes precedence
• 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: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/021 operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/0627 with sealing means on a part of the body other than the face, e.g. helmets, hoods or domes
• CPC Class Codes: A61M 16/0672 Nasal cannula assemblies for oxygen therapy
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2230/40 Respiratory characteristics

Abstract

An arrangement and method for detecting spontaneous respiratory effort of a patient receiving ventilatory support via a breathing circuit. A patient/breathing circuit interface is adapted to provide a closed connection between a breathing passage of the patient and the breathing circuit. A sensor is disposed at least partially in the breathing passage of the patient and arranged to sense flow of gas through the breathing passage. The arrangement and method individually or in addition to the airway pressure measurement promotes reliable and rapid detection of breathing efforts of a non-intubated patient to promote efficient augmentation of patient breathing.

Claims

1. A method for detecting spontaneous respiratory effort of a patient connected to a patient/breathing circuit interface and receiving ventilatory support, the method comprising the steps of:

placing a pressure sensor at least partially into a breathing passage of the patient, wherein the pressure sensor is disposed between the interface and the patient; and

monitoring changes in the airway pressure;

monitoring a direction of change of differential pressure along the breathing passage of the patient; and

comparing the changes in airway pressure and the direction of the change in differential pressure to detect a spontaneous patient respiratory effort.

2. The method of claim 1, wherein monitoring the change in airway pressure comprises the step of comparing a differential pressure measurement to a previous differential pressure measurement to determine if the pressure is rising or falling within the patient'"'"'s breathing passage.

3. The method of claim 1, wherein the breathing passage is a nasal passage of the patient.

4. The method of claim 1, wherein the pressure sensor comprises upper and lower cannulas that are offset relative to each other, wherein the upper cannula is placed deeper into the breathing passage of the patient than the first cannula.

5. The method of claim 4, wherein the step of monitoring the direction of change of the differential pressure along the breathing passage of the patient comprises the steps of:

(a) calculating the differential between first and second pressures taken from the upper nasal cannula at one moment in time;

(b) calculating the differential between first and second pressures taken from the lower nasal cannula at the one moment in time;

(c) calculating the differential between the differentials obtained in steps (a) and (b);

(d) calculating the differential between third and fourth pressures taken from the upper nasal cannula a subsequent moment in time;

(e) calculating the differential between third and fourth pressures taken from the lower nasal cannula at the subsequent moment in time;

(f) calculating differential between the differentials obtained in steps (d) and (e); and

(g) comparing the differential obtained in step (c) to the differential obtained in step (f) to determine the direction of change of the differential pressure along the breathing passage of the patient.

6. The method of claim 1, comprising the step of providing expiratory support to the patient if the airway pressure is rising and the direction of change in differential pressure is higher proximal to the patient.

7. The method of claim 1, comprising the step of maintaining a current phase of respiratory support to the patient if the airway pressure is rising and the direction of change in differential pressure is lower proximal to the patient.

8. The method of claim 1, comprising the step of maintaining a current phase of respiratory support to the patient if the airway pressure is falling and the direction of change in differential pressure is higher proximal to the patient.

9. The method of claim 1, comprising the step of providing inspiratory support to the patient if the airway pressure is falling and the differential pressure is lower proximal to the patient.

10. An arrangement for detecting spontaneous respiratory effort of a patient receiving ventilatory support via a patient breathing circuit, the arrangement comprising:

a patient/breathing circuit interface, the interface being configured to provide a closed connection between a breathing passage of the patient and the breathing circuit;

a sensing device, the sensing device comprising a differential pressure sensor configured to be at least partially disposed in the breathing passage of the patient and to sense a flow of gas through the breathing passage and changes in airway pressure; and

a controller, the controller configured to compare changes in airway pressure and a direction of change in differential pressure along the breathing passage to detect a spontaneous patient respiratory effort.

11. The arrangement of claim 10, wherein the controller is configured to monitor the change in airway pressure by comparing a differential pressure measurement to a previous differential pressure measurement to determine if the pressure is rising or falling within the patient'"'"'s breathing passage.

12. The arrangement of claim 10, wherein the breathing passage is a nasal passage of the patient.

13. The arrangement of claim 10, wherein the pressure sensor comprises upper and lower cannnulas that are offset relative to each other, wherein the upper cannula is configured to be placed deeper into the breathing passage of the patient than the first cannula.

14. The arrangement of claim 13, wherein the controller is configured to monitor the direction of change of the differential pressure along the breathing passage of the patient by:

(a) calculating the differential between first and second pressures taken from the upper nasal cannula at one moment in time;

(b) calculating the differential between first and second pressures taken from the lower nasal cannula at the one moment in time;

(c) calculating the differential between the differentials obtained in steps (a) and (b);

(d) calculating the differential between third and forth pressures taken from the upper nasal cannula a subsequent moment in time;

(e) calculating the differential between third and forth pressures taken from the lower nasal cannula at the subsequent moment in time;

(f) calculating differential between the differentials obtained in steps (d) and (e); and

(g) comparing the differential calculated in step (c) to the differential obtained in step (f) to determine the direction of change of the differential pressure along the breathing passage of the patient.

15. The arrangement of claim 10, wherein the controller is configured to control a ventilator to provide expiratory support to the patient if the airway pressure is rising and the direction of change in differential pressure is higher proximal to the patient.

16. The arrangement of claim 10, wherein the controller is configured to control a ventilator to maintain a current phase of respiratory support to the patient if the airway pressure is rising and the direction of change in differential pressure is lower proximal to the patient.

17. The arrangement of claim 10, wherein the controller is configured to control a ventilator to maintain a current phase of respiratory support to the patient if the airway pressure is falling and the direction of change in differential pressure is higher proximal to the patient.

18. The arrangement of claim 10, wherein the controller is configured to control a ventilator to provide inspiratory support to the patient if the airway pressure is falling and the differential pressure is lower proximal to the patient.