Method and apparatus for measuring and treating shivering during therapeutic temperature control

• US 20100087900A1
• Filed: 10/08/2009
• Published: 04/08/2010
• Est. Priority Date: 10/08/2008
• Status: Active Grant

• Current Assignee: Alexander C. Flint
• Original Assignee: Bedrock Inventions, LLC
• Inventors: Flint, Alexander C.
• Granted Patent: US 8,706,207 B2
• Time in Patent Office: Days
• US Class Current: 607/104
• CPC Class Codes: A61B 2560/0266 for monitoring or limiting apparatus function
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/1101 Detecting tremor
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/33 specially adapted for cooperation with other devices
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61F 2007/0095 with a temperature indicator
• CPC Class Codes: A61F 2007/0215 containing liquids other than water
• CPC Class Codes: A61F 2007/0295 for heating or cooling or use at more than one temperature
• CPC Class Codes: A61F 7/00 Heating or cooling appliances for medical or therapeutic treatment of the human body heating or cooling means in connection with bedsteads or mattresses A47C21/00 ; massage, therapeutic baths A61H; hyperthermia using electric or magnetic fields or ultrasound A61N; electric heating elements H05B
• CPC Class Codes: A61F 7/007 characterised by electric heating
• CPC Class Codes: A61F 7/0085 Devices for generating hot or cold treatment fluids
• CPC Class Codes: A61F 7/0097 Blankets with active heating or cooling sources warming mats A61F7/08
• CPC Class Codes: A61F 7/08 Warming pads, pans or mats A61F7/02 takes precedence; Hot-water bottles
• CPC Class Codes: A61F 7/10 Cooling bags, e.g. ice-bags
• CPC Class Codes: A61F 7/12 Devices for heating or cooling internal body cavities

Abstract

Methods and apparatus for the prevention and treatment of shivering encountered during therapeutic temperature regulation are disclosed that utilize an active system of counterwarming such that the timing and intensity of warmth provided to selected body areas is regulated dynamically in response to such factors as the extent of cooling applied to the core, the degree of shivering encountered, and patient temperature. Additionally, methods and apparatus are disclosed for the measurement and quantification of shivering for use in this and other applications.

Claims

1. A method for quantifying shivering in a subject, comprising obtaining a signal from a muscle mass that is susceptible to shivering, the signal including an ECG component and an EMG component, and quantifying shivering by analysis of the signal.

2. The method of claim 1, further comprising displaying a measure of the intensity of the quantified shivering.

7. The method of claim 1 wherein obtaining the signal comprises obtaining an electrical signal from one or more electrodes.

8. The method of claim 7 wherein obtaining the signal comprises obtaining an EMG signal.

9. The method of claim 7 wherein obtaining the signal comprises obtaining an ECG+EMG signal.

10. The method of claim 1 wherein obtaining the signal comprises directly detecting vibration of the muscle mass and detecting an electric signal from the muscle mass.

3. A method for quantifying shivering in a subject, comprising obtaining a signal from a muscle mass that is susceptible to shivering;

and quantifying shivering by analysis of the signal using an autocorrelation followed by a Fourier analysis.

4. The method of claim 3, further comprising displaying a measure of the intensity of the quantified shivering.

5. The method of claim 3 wherein obtaining the signal comprises detecting movement using a motion detector.

6. The method of claim 3 wherein obtaining the signal comprises detecting movement using an accelerometer.

11. A method for quantifying shivering in a subject, comprising detecting a combined ECG and EMG signal from a muscle mass that is susceptible to shivering and processing the signal to remove the ECG component;

and quantifying shivering by analysis of the processed signal.

12. The method of claim 11 wherein detecting the combined ECG+EMG signal comprises detecting a signal from one or more electrodes at one or more sites overlying the muscle mass.

13. The method of claim 11 wherein detecting a combined ECG+EMG signal comprises detecting a signal from one or more electrodes at one or more sites.

14. The method of claim 11, further comprising digitizing the combined ECG and EMG signal, and performing a wave analysis on the digitized combined signal.

15. The method of claim 14 wherein performing a wave analysis comprises performing a spectral density analysis on the combined signal.

16. The method of claim 14 wherein performing a wave analysis comprises carrying out a wave analysis on a frequency range of the spectrum that is known to correspond to a shivering EMG.

17. The method of claim 11 wherein processing the signal comprises digitizing the combined signal, segmenting the digitized combined signal to a set of traces, each said trace comprising at least a portion of a cardiac cycle, signal averaging the digitized traces to provide ECG data having a reduced contribution of EMG data, and subtracting the averaged ECG data from the combined EMG and ECG data to yield shivering EMG traces having a reduced contribution of ECG data.

18. The method of claim 17, comprising aligning the traces based on a feature of the ECG waveform.

19. The method of claim 18, comprising aligning the traces based on the peak of the QRS complex of the ECG.

20. The method of claim 18, comprising signal averaging a selected segment of the traces, the selected segment including regions having minimal ECG data elements.

21. The method of claim 11, further comprising detecting atypical ECG morphologies and removing traces containing atypical ECG morphologies from further analysis.

22. The method of claim 14 wherein performing the wave analysis comprises carrying out an averaged FFT analysis.

23. The method of claim 22 wherein carrying out the averaged FFT analysis comprises performing a FFT on each shivering EMG tracing, and averaging the resulting FFT spectra to yield an averaged FFT spectrum.

24. The method of claim 17, further comprising performing an autocorrelation function on each shivering EMG trace, and performing a wave analysis on the results of the autocorrelation.

25. The method of claim 24 wherein performing a wave analysis comprises performing a Fourier analysis.

26. The method of claim 14 wherein quantifying shivering comprises determining the amplitude of the peak spectral power within a frequency range that is typical for shivering EMG.

27. The method of claim 14 wherein quantifying shivering comprises determining the area under the curve of the spectral power within a frequency range that is typical for shivering EMG.

28. The method of claim 14 wherein quantifying shivering comprises analyzing appearances of different peaks corresponding to different frequencies of shivering that occur as shivering becomes more intense.

29. The method of claim 14 wherein quantifying shivering comprises analyzing change of spectral peaks or patterns as a function of time.

30. A method for quantifying shivering in a subject, comprising:

at a time when the subject would not be expected to shiver, obtaining a first signal from a muscle mass that is susceptible to shivering, and processing the baseline signal by spectral analysis;

at a time when the subject may be expected to shiver, obtaining a second signal, and processing the second signal by spectral analysis; and

subtracting the results of one spectral analysis from the result of the other spectral analysis to obtain a spectrum that represents only a shivering component.

31. A method for treating shivering in a subject in the course of therapeutic temperature regulation comprising applying active counterwarming for inhibition of shivering.

32. The method of claim 31 wherein applying active counterwarming operates in a feedback system.

33. The method of claim 31 wherein the therapeutic temperature regulation comprises applying core cooling to the subject.

34. The method of claim 31 wherein counterwarming is applied in response to quantified shivering.

35. The method of claim 31 wherein counterwarming is applied in response to change in the core temperature of the subject.

36. The method of claim 33 wherein counterwarming is applied in response to the amount of core cooling being applied.

37. The method of claim 31 wherein counterwarming is applied in response to a combination of one or more of quantified shivering, change in core temperature of the subject, or applied core cooling.

38. Apparatus for quantifying shivering in a subject, comprising means for obtaining a signal from a muscle mass that is susceptible to shivering, the signal including an ECG component and an EMG component, and means for analyzing the signal.

43. The apparatus of claim 38 wherein the indirect motion detector comprises one or more electrodes adapted for placement in or on a surface of the body of the patient.

44. The apparatus of claim 43 wherein the indirect motion detector comprises one or more ECG electrodes.

45. The apparatus of claim 43 wherein the indirect motion detector comprises one or more EMG electrodes.

46. The apparatus of claim 38 wherein the means for analyzing the signal comprises a signal processor adapted to receive signals from the means for obtaining the signal from the muscle mass.

39. Apparatus for quantifying shivering in a subject, comprising means for obtaining a signal from a muscle mass that is susceptible to shivering;

and means for analyzing the signal using an autocorrelation followed by a Fourier analysis.

40. The apparatus of claim 39 wherein the means for obtaining a signal comprises a direct motion detector and electrical or wireless operative connection between the detector and a signal processor.

41. The apparatus of claim 40 wherein the direct motion detector comprises an accelerometer.

42. The apparatus of claim 39 wherein the means for obtaining a signal comprises an indirect motion detector and electrical or wireless operative connection between the detector and a signal processor.

47. The apparatus of claim 39 wherein the means for analyzing the signal comprises a signal processor adapted to receive signals from the means for obtaining the signal from the muscle mass.

48. A method for applying active counterwarming to a subject during therapeutic temperature regulation of the subject, the therapeutic temperature regulation including cooling to reduce the core temperature of the subject, comprising regulating application of warming to one or more selected sites on the subject'"'"'s body.

49. The method of claim 48 wherein the selected site includes a body area not used for cooling the core.

50. The method of claim 48 wherein applying counterwarming includes one or a combination of any of:

changing the temperature of warming applied to all treated body regions, changing the temperature of warming applied to specific treated body regions, changing the pattern of warming applied to selected treated body regions.

51. Apparatus for applying active counterwarming to a subject, comprising apparatus for quantifying shivering in a subject and apparatus for warming selected areas of the patient'"'"'s body.

52. Apparatus for applying active counterwarming to a subject during therapeutic temperature regulation of the subject, comprising apparatus for quantifying shivering in the subject and apparatus for warming selected areas of the subject'"'"'s body, and further comprising apparatus for cooling the patient to lower the core temperature.

53. The apparatus of claim 52 wherein the apparatus for cooling the subject comprises a temperature set point feedback device operatively connected to cooling apparatus, and a core temperature sensor operatively connected to the temperature set point feedback device.

54. The apparatus of claim 52 wherein the cooling apparatus comprises one or more of a cooling blanket, cooling pads, and an endovascular cooling catheter.

55. The apparatus of claim 52 wherein the apparatus for warming selected areas of the body includes counterwarming elements, and a counterwarming controller operatively connected to the counterwarming elements and configured and adapted to adjust the warming applied to the counterwarming elements.

56. The apparatus of claim 55 wherein the counterwarming controller is operatively connected to one or a combination of two or more of:

a core temperature sensor;

a core cooling controller;

and the apparatus for quantifying shivering.

57. The apparatus of claim 55 wherein the counterwarming elements include heating apparel.

58. The apparatus of claim 55 wherein the counterwarming elements include one or more of:

heated mittens, heated booties, heated ear muffs, heated blankets, and heated pads.

59. The apparatus of claim 55 wherein the counterwarming elements are heated by means for heat transfer.

60. The apparatus of 59 wherein the means for heat transfer comprise one or more of a circulating warm liquid, or insulated electrical heating coils.

61. The apparatus of 55 wherein the counterwarming elements include apparatus configured for infusion of a suitable warm sterile liquid into the external auditory canals of both ears of the patient.

62. A method for isolating a first signal from a combined signal containing first and second signals, wherein the second signal includes recurring epochs of a stereotyped waveform, by:

digitally sampling the combined signal at a suitable sample rate;

storing in memory a number of epochs of the combined signal;

averaging the stored epochs of the combined signal to obtain an average of the recurring epochs of the stereotyped second signal waveform; and

, using a microprocessor, subtracting the average recurring epoch from each of at least a subset of the epochs of the combined signal and storing the results, containing isolated first signal epochs substantially free of second signal features, in memory.