Method and apparatus for processing respiration data and assessing autonomic function

• US 20050251056A1
• Filed: 07/20/2004
• Published: 11/10/2005
• Est. Priority Date: 05/10/2004
• Status: Active Application

• Current Assignee: Meddorna LLC
• Original Assignee: MedPond, LLC
• Inventors: Zhirnov, Yevgeniy N., Gribkov, Evgueni N., Pougatchev, Vadim I.
• Application Number:
  US10/894,985
• Publication Number:
  US 20050251056A1
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: G16H 50/70 for mining of medical data, e.g. analysing previous cases of other patients
• CPC Class Codes: Y10S 128/92 Computer assisted medical diagnostics

Abstract

Embodiments of the invention concern methods and apparatuses for deriving respiratory data from both single lead and multi-lead ECG data recordings. Other embodiments of the invention address the assessment of respiration rate from respiratory data such as respiratory data derived from ECG data. Still other embodiments of the invention address methods and apparatuses for the assessment of autonomic function. These last embodiments involve the derivation of respiratory data from ECG data, comparing the respiration rate to key threshold values, and the final derivation of one or more HRV parameters from the ECG data. The embodiments of the invention have implementations applicable to data previously recorded data as well as data recorded and processed in a real-time manner.

Claims

1. A method for deriving respiration data from ECG data comprising the steps of:

receiving ECG data, derived from a single lead ECG recording, wherein the ECG data comprises a plurality of cardiac complexes;

determining a first fiduciary point and a second fiduciary point for each of the plurality of cardiac complexes, wherein a plurality of intermediate points exist between the first fiduciary point and the second fiduciary point for each of the plurality of cardiac complexes;

determining an amplitude for each of the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the plurality of cardiac complexes;

summing the amplitudes for the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the plurality of cardiac complexes, thereby determining a plurality of sums that correspond to the plurality of cardiac complexes; and

deriving a respiratory signal using the plurality of sums.

2. The method of claim 1 wherein the step of deriving the respiratory signal utilizes the following equation:

$Y<br><br>\left(t_n\right)=\underset{i=0}{\overset{3}{\sum <br><br>}}<br><br>\left(A<br><br>\left[k-i\right]*\underset{j=0,j\ne <br><br>i}{\overset{3}{\prod <br><br>}}<br><br>\left(t_n-T<br><br>\left[k-j\right]\right)/\underset{j=0,j\ne <br><br>i}{\overset{3}{\prod <br><br>}}<br><br>\left(T<br><br>\left[k-i\right]-T<br><br>\left[k-j\right]\right)\right)$

wherein;

Y(t_n)=an amplitude of the respiratory signal at time(t_n);

t_n=n*0.2 sec, wherein n is an index value for a sample (e.g., n=0 denotes a 1^st sample);

A[k]=a sum of amplitudes for a k cardiac complex, wherein k is an index value (e.g., k=0 denotes a 1^st cardiac complex); and

T[k]=a time associated with a R wave that is associated with the k cardiac complex.

3. The method of claim 1 further comprising a step of raising the amplitude for each of the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the plurality of cardiac complexes to a power greater than one, wherein the step of raising the amplitude for each of the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the plurality of cardiac complexes to a power greater than one is performed before the step of summing the amplitudes for the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the plurality of cardiac complexes.

4. The method of claim 1 wherein the step of receiving ECG data comprises the step of recording the ECG data from a patient.

5. The method of claim 4 wherein the steps of recording the ECG data and deriving the respiratory signal using the plurality of sums occur in a substantially real-time manner.

6. The method of claim 1 wherein the first fiduciary point is a PQ point and the second fiduciary point is a J point.

7. One or more program storage media readable by a machine and containing instructions for performing the method contained in claim 1.

8. A method for deriving respiration data from ECG data comprising the steps of:

receiving first ECG data, derived from a single lead ECG recording, wherein the first ECG data comprises a first plurality of cardiac complexes;

determining a first fiduciary point and second fiduciary point for each of the first plurality of cardiac complexes, wherein a plurality of intermediate points exist between the first fiduciary point and the second fiduciary point for each of the first plurality of cardiac complexes;

determining an amplitude for each of the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the first plurality of cardiac complexes;

summing the amplitudes for the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the first plurality of cardiac complexes, thereby determining a first plurality of sums that correspond to the first plurality of cardiac complexes;

receiving second ECG data, derived from a second single lead ECG recording, wherein the second ECG data comprises a second plurality of cardiac complexes that correspond with the first plurality of cardiac complexes;

determining a first fiduciary point and second fiduciary point for each of the second plurality of cardiac complexes, wherein a plurality of intermediate points exist between the first fiduciary point and the second fiduciary point for each of the second plurality of cardiac complexes;

determining an amplitude for each of the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the second plurality of cardiac complexes;

summing the amplitudes for the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the second plurality of cardiac complexes, thereby determining a second plurality of sums that correspond to the second plurality of cardiac complexes;

determining a plurality of arctangent values for the first plurality of sums divided by the second plurality of sums, wherein the plurality of arctangent values correspond to the first plurality of cardiac complexes and the second plurality of cardiac complexes;

deriving a respiratory signal using the plurality of arctangent values.

9. The method of claim 8 wherein the step of deriving the respiratory signal utilizes the following equation:

$Y<br><br>\left(t_n\right)=\underset{i=0}{\overset{3}{\sum <br><br>}}<br><br>\left(A<br><br>\left[k-i\right]*\underset{j=0,j\ne <br><br>i}{\overset{3}{\prod <br><br>}}<br><br>\left(t_n-T<br><br>\left[k-j\right]\right)/\underset{j=0,j\ne <br><br>i}{\overset{3}{\prod <br><br>}}<br><br>\left(T<br><br>\left[k-i\right]-T<br><br>\left[k-j\right]\right)\right)$

wherein;

Y(t_n)=an amplitude of the respiratory signal at time (t_n)

t_n=n*0.2 sec, wherein n is an index value for a sample (e.g., n=0 denotes a 1^st sample);

A[k]=arctangent for k of the first plurality of sums divided by k of the second plurality of sums, wherein k is an index value (e.g., k=0 denotes a 1^st cardiac complex); and

T[k]=a time associated with a R wave that is associated with the k cardiac complex.

10. The method of claim 8 further comprising the step of raising the amplitudes for the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the first plurality of cardiac complexes to a power greater than one before performing the step of summing the amplitudes for the plurality of intermediate points between the first fiduciary point and the second fiduciary point for each of the first plurality of cardiac complexes.

11. The method of claim 8 wherein the step of receiving first ECG data comprises the step of recording the first ECG data from a patient.

12. The method of claim 11 wherein the steps of recording the first ECG data and deriving the respiratory signal using the plurality of arctangent values occur in a substantially real-time manner.

13. The method of claim 8 wherein the first fiduciary point for each of the first plurality of cardiac complexes is a PQ point and the second fiduciary point for each of the first plurality of cardiac complexes is a J point.

14. One or more program storage media readable by a machine and containing instructions for performing the method contained in claim 8.

15. A method for deriving a respiration rate from respiration data comprising the steps of:

receiving respiration data;

deriving, from the respiration data, a first minimum amplitude point, a first maximum amplitude point, a second minimum amplitude point and a second maximum amplitude point;

deriving a first amplitude range, wherein the first amplitude range is a difference in amplitude between the first minimum amplitude point and the first maximum amplitude point;

deriving a second amplitude range, wherein the second amplitude range is a difference in amplitude between the second minimum amplitude point and the first maximum amplitude point;

comparing the first amplitude range to a first value;

deriving a respiration rate in response to the step of comparing the first amplitude range to a first value.

16. The method of claim 15 wherein the respiration data is derived from a single lead ECG recording.

17. The method of claim 15 wherein the step of receiving respiration data comprises the step of recording physiological signals from a patient.

18. The method of claim 17 wherein the steps of recording the physiological signals from the patient and deriving the respiration rate in response to the step of comparing the first amplitude range to a first value occur in a substantially real-time manner.

19. The method of claim 15 further comprising the step of indicating if the respiration rate is less than a predetermined value.

20. The method of claim 15 wherein the first value is derived from an array comprised of previously derived amplitude ranges.

21. The method of claim 15 wherein the first value is substantially equal to the second amplitude range.

22. The method of claim 15 wherein the step of deriving the respiration rate in response to the step of comparing the first amplitude range to a first value is further conducted in response to the following steps:

determining a first period of time that elapses between the first minimum amplitude point and the first maximum amplitude point;

determining a second period of time that elapses between the second minimum amplitude point and the first maximum amplitude point; and

comparing a second value to a predetermined value, wherein the second value is derived by dividing the first period of time by the sum of the first and second periods of time.

23. The method of claim 15 wherein the step of deriving the respiration rate utilizes the following equation:

60/(the second maximum amplitude point−

the first maximum amplitude point)*0.2.

24. The method of claim 15 wherein the step of deriving the respiration rate in response to the step of comparing the first amplitude range to a first value directly follows the step of comparing the first amplitude range to a first value.

25. One or more program storage media readable by a machine and containing instructions for performing the method contained in claim 15.

26. A method for assessing autonomic function comprising the steps of:

receiving ECG data;

deriving respiratory data from the ECG data;

deriving a respiratory rate from the respiratory data;

comparing the respiratory rate to a first value, wherein the first value is a respiration rate conducive to proper assessment of a patient'"'"'s autonomic function; and

deriving one or more HRV parameters from the ECG data in response to the step of comparing the respiratory rate to a first value, wherein the HRV parameters are indicative of the patient'"'"'s autonomic function.

27. The method of claim 26 wherein the step of receiving the ECG data comprises the step of recording the ECG data from the patient.

28. The method of claim 27 wherein the steps of recording the ECG data and deriving the respiratory rate occur in a substantially real-time manner.

29. The method of claim 27 wherein the steps of recording the ECG data, deriving the respiratory rate and deriving one or more HRV parameters from the ECG data in response to the step of comparing the respiratory rate to a first value occur in a substantially real-time manner.

30. The method of claim 26 wherein the step of receiving ECG data comprises the step of digitizing analog ECG data to receive the ECG data.

31. The method of claim 26 wherein the ECG data is derived from a single lead ECG recording.

32. The method of claim 26 wherein the one- or more HRV parameters are selected from the group consisting of:

30;

15 Ratio, NNmin Standing, NNmax Standing, Tmax, Trec, E/I Ratio, SD, NNmin SB, NNmax SB, VARmax, VARmean, RMS-SD, NN, SDNN, TP, LFnorm, HFnorm, LF/HF, VLF, LF, HF, VR and combinations thereof.

33. The method of claim 26 wherein the one or more HRV parameters are selected from the group consisting of:

TP, LFnorm, HFnorm, LF/HF, VLF, LF, HF and combinations thereof.

34. One or more program storage media readable by a machine and containing instructions for performing the method contained in claim 26.

35. A system for assessing autonomic function comprising:

a memory unit operable for storing one or more computer products for assessing autonomic performance; and

a processor coupled to the memory unit, wherein the processor executes the one or more computer products for performing the steps of;

receiving ECG data;

deriving respiratory data from the ECG data;

deriving a respiratory rate from the respiratory data;

comparing the respiratory rate to a first value, wherein the first value is a respiration rate conducive to proper assessment of a patient'"'"'s autonomic function; and

deriving one or more HRV parameters from the ECG data in response to the step of comparing the respiratory rate to a first value, wherein the HRV parameters are indicative of the patient'"'"'s autonomic function.

36. The system of claim 35, wherein the step of receiving the ECG data comprises the step of recording the ECG data from the patient.

37. The system of claim 36, wherein the steps of recording the ECG data and deriving the respiratory rate occur in a substantially real-time manner.

38. The system of claim 36, wherein the steps of recording the ECG data, deriving the respiratory rate and deriving one or more HRV parameters from the ECG data in response to the step of comparing the respiratory rate to a first value occur in a substantially real-time manner.

39. The system of claim 35, wherein the step of receiving ECG data comprises the step of digitizing analog ECG data to receive the ECG data.

40. The system of claim 35, wherein the ECG data is derived from a single lead ECG recording.

41. The system of claim 35, wherein the one or more HRV parameters are selected from the group consisting of:

30;

15 Ratio, NNmin Standing, NNmax Standing, Tmax, Trec, E/I Ratio, SD, NNmin SB, NNmax SB, VARmax, VARmean, RMS-SD, NN, SDNN, TP, LFnorm, HFnorm, LF/HF, VLF, LF, HF, VR and combinations thereof.

42. The system of claim 35 wherein the one or more HRV parameters are selected from the group consisting of:

TP, LFnorm, HFnorm, LF/HF, VLF, LF, HF and combinations thereof.