RESPIRATORY FUNCTION DETECTION

• US 20130197386A1
• Filed: 01/18/2013
• Published: 08/01/2013
• Est. Priority Date: 01/31/2012
• Status: Abandoned Application

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Cho, Yong K., Erickson, Mark K., Hettrick, Douglas A.
• Application Number:
  US13/744,461
• Publication Number:
  US 20130197386A1
• Time in Patent Office: Days
• US Class Current: 600/533
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 7/00 Instruments for auscultation

Abstract

A system and method for monitoring respiratory function that includes an acoustic sensing device sensing an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient, and a processor configured to determine changes in high frequency acoustic amplitude associated with the sensed acoustic waveform and, in response to the determined changes in high frequency acoustic amplitude, determine an indication of respiratory function.

Claims

1. A method for monitoring respiratory function, comprising:

sensing an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient;

determining changes in high frequency acoustic amplitude associated with the sensed acoustic waveform; and

determining an indication of respiratory function in response to the determined changes in high frequency acoustic amplitude.

2. The method of claim 1, further comprising:

determining changes in low frequency acoustic amplitude associated with the sensed acoustic waveform; and

determining the indication of respiratory function in response to the determined changes in low frequency acoustic amplitude, wherein determining an indication of respiratory function further comprises;

determining a first indication of respiratory function in response to determined changes in high frequency acoustic amplitude; and

determining a second indication of repiratory function different from the first indication of respiratory function in response to determined changes in low frequency acoustic amplitude.

3. The method of claim 2, further comprising:

receiving a first thoracic impedance waveform for at least one breath of a patient;

determining a first breath slope value in response to on the first thoracic impedance waveform; and

comparing the first breath slope value to a first threshold slope value of the patient, wherein determining an indication of respiratory function further comprises determining the indication of respiratory function in response to the comparing.

4. The method of claim 3, further comprising determining whether the first thoracic impedance waveform was collected in response to a first activation event, wherein the first threshold slope value is a first baseline slope value and wherein the first baseline slope value is associated with the first activation event.

5. The method of claim 4, further comprising:

comparing the first thoracic impedance waveform to the first baseline impedance waveform, the first baseline impedance waveform collected in response to a baseline activation event, the baseline activation event corresponding to the first activation event;

in response to the comparing the first thoracic impedance waveform to the first baseline impedance waveform, detecting a change in patient status;

in response to a detected change in patient status, associating the first thoracic impedance waveform with the new patient status; and

storing the new patient status and the first impedance waveform.

6. The method of claim 4, further comprising:

receiving a second thoracic impedance waveform;

determining whether the second thoracic impedance waveform was collected in response to a second activation event different from the first activation event;

determining a second breath slope value in response to the second thoracic impedance waveform;

comparing the second breath slope to a second baseline slope value associated with the second activation event;

comparing a difference between the first breath slope value and the first baseline slope value and a difference between the second breath slope value and the second baseline slope value; and

in response to the comparison of the differences, determining whether a change in relative respiratory function has occurred.

7. The method of claim 1, further comprising:

determining an area under the curve of the at least one breath, and

comparing the area under the curve of the at least one breath to a threshold area under the curve value;

wherein determining an indication of respiratory function of the patient further comprises determining the indication of respiratory function of the patient in response to the comparison of the area under the curve of the at least one breath.

8. The method of claim 7, wherein the area under the curve for the breath is the area under the curve during inspiration.

9. The method of claim 7, wherein the area under the curve for the breath is the area under the curve for expiration.

10. The method of claim 3, wherein the first breath slope value is a long term average of inspiration slope value, the method further comprising determining a ratio between the long term average of inspiration slope value and a long term average of expiration slope value.

11. A system for monitoring respiratory function, the system comprising:

an acoustic sensing device sensing an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient; and

a processor configured to determine changes in high frequency acoustic amplitude associated with the sensed acoustic waveform, and determine an indication of respiratory function in response to the determined changes in high frequency acoustic amplitude.

12. The system of claim 11, wherein the processor is further configured to determine changes in low frequency acoustic amplitude associated with the sensed acoustic waveform, and determine the indication of respiratory function in response to the determined

changes in low frequency acoustic amplitude, wherein determining an indication of respiratory function further comprises:

determining a first indication of respiratory function in response to determined changes in high frequency acoustic amplitude; and

determining a second indication of repiratory function different from the first indication of respiratory function in response to determined changes in low frequency acoustic amplitude.

13. The system of claim 12, the system comprising:

an impedance sensor, the impedance sensor configured to collect a first thoracic impedance waveform for at least one breath of a patient; and

a memory configured to store a first threshold slope value, wherein the processor is further configured to determine a first breath slope value in response to the impedance waveform, and compare the first breath slope value to a first threshold slope value, wherein determining an indication of respiratory function further comprises determining the indication of respiratory function in response to the comparing.

14. The system of claim 13, wherein the processor is further configured to determine whether the first thoracic impedance waveform was collected in response to a first activation event, wherein the first threshold slope value is a first baseline slope value and wherein the first baseline slope value is associated with the first activation event.

15. The system of claim 14, wherein the processor is further configured to:

compare the first thoracic impedance waveform to the first baseline impedance waveform, the first baseline impedance waveform collected in response to an original activation event, the original activation event corresponding to the first activation event;

detect a change in patient status in response to the comparing the first thoracic impedance waveform to the first baseline impedance waveform;

in response to a change in patient status, associate the first thoracic impedance waveform with the new patient status; and

store the new patient status and the first impedance waveform in the memory.

16. The system of claim 14, wherein

the impedance sensor is further configured to collect a second thoracic impedance waveform;

and

the processor further configured to;

determine whether the second thoracic impedance waveform was collected in response to a second activation event different from the first activation event;

determine a second breath slope value in response to on the second thoracic impedance waveform;

compare the second breath slope to a second baseline slope value associated

with the second activation event;

compare a difference between the first breath slope value and the first baseline

slope value and a difference between the second breath slope value and the second baseline slope value; and

in response to the comparison of the differences, determine whether a change

in relative respiratory function has occurred.

17. The system of claim 13, wherein the processor is further configured to:

determine an area under the curve of the at least one breath;

compare the area under the curve of the at least one breath to a threshold area under the curve value; and

determine the indication of respiratory function in response to the comparison of the area under the curve of the at least one breath.

18. The system of claim 17, wherein the processor is configured to determine the area under the curve during inspiration.

19. The system of claim 17, wherein the processor is configured to determine the area under the curve during expiration.

20. The system of claim 13, wherein the processor is further configured to determine a long term average of inspiration slope value, determine a long term average of expiration slope value, and determine a ratio between the long term average of inspiration slope value and the long term average of expiration slope value.

21. A computer-readable medium comprising instructions for causing a programmable processor to:

sense an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient;

determine changes in high frequency acoustic amplitude associated with the sensed acoustic waveform; and

determine an indication of respiratory function in response to the determined changes in high frequency acoustic amplitude.