Method and system for monitoring breathing activity of a subject

• US 20040071337A1
• Filed: 12/20/2002
• Published: 04/15/2004
• Est. Priority Date: 10/23/1998
• Status: Active Grant

• Current Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Mostafavi, Hassan, Zdasiuk, George, Sutherland, Robert M., Riaziat, Majid L., Jeung, Andrew
• Granted Patent: US 7,123,758 B2
• Time in Patent Office: Days
• US Class Current: 382/151
• CPC Class Codes: A61B 2090/371 with simultaneous use of two cameras
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/1127 using markers
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7289 Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition
• CPC Class Codes: A61B 6/463 characterised by displaying multiple images or images and diagnostic data on one display
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61N 2005/1059 using cameras imaging the patient
• CPC Class Codes: A61N 5/1048 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/1064 for adjusting radiation treatment in response to monitoring

Abstract

A method and system for monitoring breathing movement of a subject is disclosed. A method and system for detecting and predictably estimating regular cycles of breathing movements is disclosed. Another disclosed aspect of the invention is directed to detect and report irregularity of breathing activity of an infant, such as cessation and non-periodicity, which suggests a likelihood of SIDS.

Claims

1. A method of monitoring breathing activity, comprising:

measuring a first set of signal data representative of a breathing movement of an infant during a first time period;

pattern matching the first set of signal data with a second set of signal data related to measured breathing movement of the infant during a second time period to identify degree of deviation from periodicity of the breathing movement; and

reporting irregularity based upon results of the pattern matching.

2. The method of claim 1 in which the first set of signal data and the second set of signal data are pattern matched using an autocorrelation function.

3. The method of claim 1 in which the first set of signal data and the second set of signal data are pattern matched using an absolute difference function.

4. The method of claim 1 further comprising:

determining a degree of match between the first set of signal data and the second set of signal data.

5. The method of claim 4 in which the degree of match is determined by a secondary peak value of an autocorrelation function.

6. The method of claim 4 in which the degree of match is determined by a secondary minimum value of an absolute difference function.

7. The method of claim 4 further comprising:

comparing the degree of match to a threshold range.

8. The method of claim 7 in which the degree of match outside the threshold range indicates deviation from a normal breathing movement.

9. The method of claim 7 in which the degree of match within the threshold range indicates a repetitive breathing movement.

10. The method of claim 9 in which a point of best match indicates a period of the breathing movement.

11. The method of claim 1 in which reporting irregularity comprises transmitting an alarm signal.

12. The method of claim 11 in which the alarm signal comprises an audible or visible signal.

13. The method of claim 1 in which irregularity comprises deviation from periodicity of the breathing movement, the degree of the deviation exceeding a threshold.

14. The method of claim 1 in which irregularity comprises deviations from periodicity of the breathing movement identified in a plurality of consecutive sets of signal data, the degrees of the deviations exceeding a threshold.

15. The method of claim 1 in which the second set of signal data is a data model of the breathing movement.

16. The method of claim 15 in which the data model of the breathing movement can be updated.

17. A method of monitoring breathing activity, comprising:

measuring a set of signal data representative of a breathing movement during a time period;

comparing amplitude of the set of signal data with a threshold; and

reporting irregularity based upon results of the comparison.

18. The method of claim 17 in which reporting irregularity comprises transmitting an alarm signal.

19. The method of claim 17 in which irregularity comprises measurement of a set of signal data, the amplitude of the set of signal data below the threshold.

20. The method of claim 17 in which irregularity comprises measurement of two or more consecutive sets of signal data, the amplitudes of the two or more sets of signal data below the threshold.

21. The method of claim 17 in which the breathing activity is for an infant.

22. A method of monitoring movement of a subject, comprising:

acquiring image data;

determining a number of markers visible in the image data;

determination if the number of markers meets a threshold value; and

reporting irregularity if the number of markers does not meet the threshold value.

23. The method of claim 22 in which the number of markers comprises three markers.

24. The method of claim 22 in which the markers are attached to a marker block.

25. The method of claim 24 in which the act of acquiring the image data occurs during a process for determining the location of the marker block.

26. The method of claim 22 in which a camera is used to acquire the image data, wherein the camera is mounted to a crib.

27. A method of monitoring movement of a subject, comprising:

receiving a set of signal data representative of a movement of the subject;

estimating phase of the set of signal data;

comparing a vector of the set of signal data with one or more prior sets of signal data to identify deviation from periodicity of the movement, the vector of the set of signal data based upon the phase, the one or more prior sets relating to measured movement of the subject during one or more prior time periods; and

reporting irregularity based upon results of the comparison.

28. The method of claim 27 in which the subject comprises an infant.

29. The method of claim 27 in which irregularity comprises identified deviation from periodicity.

30. The method of claim 27 in which irregularity comprises deviations from periodicity identified in a plurality of consecutive sets of signal data.

31. The method of claim 27 in which the phase is estimated by calculating period of the set of signal data.

32. The method of claim 31 further comprising

computing an inner product of a Cosine waveform with the period T and most recent T-seconds-long segment of the signal data to form an in-phase component;

computing the inner product with a Sine waveform of the period T to form a quadrature component; and

computing the inverse Tangent of result of dividing the quadrature component by the in-phase component to estimate the phase.

33. The method of claim 31 further comprising:

identifying an assumption for the period;

estimate location values for maximum and minimum values; and

based upon one or more sample sets, estimating the period.

34. The method of claim 27 in which the vector comprises amplitude and phase components.

35. The method of claim 27 in which the act of comparing the vector of the set of signal data with the one or more prior sets of signal data to identify deviation from periodicity of the breathing movement comprises:

using a 2-dimensional histogram array of signal versus phase values.

36. The method of claim 35 in which the 2-dimensional histogram array is accumulated during prior recordings of the movement.

37. The method of claim 35 further comprising:

comparing the vector with other values in the 2-dimensional histogram array;

forming a clustering factor; and

identifying deviation from periodicity if clustering factor exceeds a threshold.

38. The method of claim 27 further comprising:

estimating latest inhale values, latest exhale extreme values, and corresponding time points.

39. A method for monitoring periodic activity, comprising:

co-locating a marker block with an object such that movement of the marker block relates to movement of the object, the marker block comprising one or more markers;

viewing the marker block with a camera;

generating image data representative of the marker block; and

reporting irregularity based upon insufficient periodicity for detected movement.

40. The method of claim 46 in which the object comprises a non-living object.

41. The method of claim 40 in which the non-living object comprises a mechanical object.

42. The method of claim 39 in which reporting irregularity comprises transmitting an alarm signal.

43. The method of claim 39 in which positions of the one or more markers are tracked using the image data.

44. The method of claim 39 in which irregularity comprises failure to locate the one or more markers within the one or more expanded search ranges.

45. The method of claim 39 further comprising:

quantifying movement for the marker block.

46. The method of claim 45 in which irregularity is determined based upon amplitude of the movement data.

47. A method for tracking independent movement of multiple groups of markers, comprising:

imaging a first group and a second group of markers using a camera to capture an image;

identifying the first group of markers in the image;

identifying the second group of markers in the image;

tracking movement of the first group of markers; and

tracking movement of the second group of markers.

48. The method of claim 47 in which a single tracking system is employed to concurrently track the movement of the first and second groups of markers.

49. The method of claim 47 in which the first group of markers is associated with a first subject and the second group of markers is associated with a second subject.

50. The method of claim 47 in which the first and second groups of markers are associated with the same subject.

51. The method of claim 50 in which the first group of markers is associated with a first body location and the second group of markers is associated with a second body location.

52. The method of claim 51 in which a first alarm threshold is associated with the first body location and a second alarm threshold is associated with the second body location.

53. The method of claim 47 in which the first group of markers is associated with a marker block.

54. The method of claim 53 in which an automated process is performed to match the first group of markers in the image to the marker block, wherein position and orientation of the marker block is analyzed.

55. The method of claim 47 in which the first and second sets of markers are tracked to detect irregularity in movement.

56. The method of claim 55 in which the irregularity comprises deviation from periodicity, insufficient number of markers, or insufficient motion.

57. The method of claim 47 in which the first and second sets of markers are tracked to detect position and orientation.