SYSTEM AND METHOD FOR DETERMINING DEPTH OF CHEST COMPRESSIONS

• US 20100228166A1
• Filed: 03/05/2010
• Published: 09/09/2010
• Est. Priority Date: 03/06/2009
• Status: Active Grant

• Current Assignee: Stryker Canada, ULC (Stryker Corporation)
• Original Assignee: Atreo Medical Inc. (Medtronic Plc)
• Inventors: CENTEN, Corey
• Granted Patent: US 8,652,077 B2
• Time in Patent Office: Days
• US Class Current: 601/41
• CPC Class Codes: A61H 2201/10 with further special therapeutic means, e.g. electrotherapy, magneto therapy or radiation therapy, chromo therapy, infrared or ultraviolet therapy
• CPC Class Codes: A61H 2201/1635 Hand or arm, e.g. handle hand-held, A61H2201/0153; fore-arm support, A61H2003/006
• CPC Class Codes: A61H 2201/5043 Displays
• CPC Class Codes: A61H 2201/5061 Force sensors
• CPC Class Codes: A61H 2201/5064 Position sensors
• CPC Class Codes: A61H 2201/5071 Pressure sensors
• CPC Class Codes: A61H 2201/5084 Acceleration sensors
• CPC Class Codes: A61H 2205/084 Chest
• CPC Class Codes: A61H 2230/065 used as a control parameter for the apparatus
• CPC Class Codes: A61H 31/00 Artificial respiration or heart stimulation, e.g. heart massage artificial respiration by treatment with gas or air, e.g. mouth-to-mouth respiration A61M16/00; applying electric currents by contact electrodes for stimulation, e.g. heart pace-makers A61N1/36 ; teaching or training models, demonstration models for medical purposes G09B23/288
• CPC Class Codes: A61H 31/004 Heart stimulation
• CPC Class Codes: A61H 31/005 with feedback for the user
• CPC Class Codes: A61H 31/007 Manual driven
• CPC Class Codes: A61H 31/008 Supine patient supports or bases, e.g. improving air-way access to the lungs
• CPC Class Codes: A61N 1/046 Specially adapted for shock therapy, e.g. defibrillation
• CPC Class Codes: A61N 1/0492 Patch electrodes A61N1/0412, A61N1/0428 take precedence
• CPC Class Codes: A61N 1/39044 in combination with cardiopulmonary resuscitation [CPR] therapy

Abstract

Systems and methods for determining depth of compressions of a chest of a patient receiving chest compressions. A field detector is used having at least two coils at a fixed distance from each other.

Claims

1. A system for determining a depth of compression of a chest of a patient receiving chest compressions, the system comprising:

a field generator adapted to generate a field;

a compound field detector including at least two coils at a fixed distance from each other, the field detector adapted to generate a response signal indicative of any one of the at least two coils detecting the field; and

a processor adapted to determine from the response signal position information for the field detector relative to the field generator, and to determine the chest compression depth from the determined position information;

wherein one of the field generator and the field detector is a position sensor adapted to move in accordance the chest as the chest is receiving the compressions, and the other of the field generator and the field detector is a reference sensor adapted to be stationary relative to the patient.

2. The system of claim 1, wherein each coil in the compound field detector comprises windings, and the windings of each coil are substantially parallel to the windings of each other coil.

3. The system of claim 1, wherein each coil in the compound field detector comprises windings, each coil having a longitudinal axis perpendicular to a plane defined by the respective windings, wherein the longitudinal axis of each coil is substantially parallel with a direction of the chest compressions.

4. The system of claim 1, wherein the field generator is coupled with the field detector via a wire.

5. The system of claim 1, wherein the field generator is coupled wirelessly with the field detector.

6. The system of claim 1 wherein the processor is further adapted to receive signals from each of the coils, determine an apparent distance between the coils, and determine a correction factor to correct for distortion in the position information, the correction factor being determined based on any differences between the apparent distance and the fixed distance between the coils.

7. The system of claim 6 wherein the processor is further adapted to define initial positions for each of the coils at a given time, wherein the apparent distance is determined based on apparent distance traveled by one of the at least two coils from its own initial position to an initial position of another of the at least two coils.

8. The system of claim 1 wherein the chest compression depth is calculated by forming a plane in space substantially perpendicular to a direction of the chest compression depth.

9. The system of claim 1 wherein the field detector is the position sensor and the field generator is the reference sensor.

10. The system of claim 1 wherein coordinates of the position information are rotated into a frame-of-reference of the position sensor.

11. The system of claim 10 wherein the chest compression depth is calculated by determining distance from a starting position coordinate of chest compression to a final position coordinate of chest compression, the final position coordinate corresponding to a final depth of chest compression.

12. The system of claim 1 wherein the field generator is adapted to be placed on the chest of the patient and the field detector is adapted to be stationary relative to the patient.

13. The system of claim 12 wherein the position information is in a frame-of-reference of the field generator and the chest compression depth is calculated by determining the distance from a starting position coordinate of chest compression to a final position coordinate of chest compression, the final position coordinate corresponding to a final depth of chest compression.

14. The system of claim 1 wherein the position information includes measured orientation angles of the position sensor.

15. The system of claim 14 wherein an angle of a direction of chest compression relative to an axis perpendicular to the patient'"'"'s chest is calculated using the orientation angles.

16. The system of claim 1 wherein the position sensor is wearable.

17. The system of claim 16 wherein a bend sensor is provided with the position sensor for sensing an orientation of the position sensor.

18. The system of claim 17 wherein measured data from the bend sensor is used to correct for noise and distortion from orientation information measured by the position sensor.

19. The system of claim 1 wherein a distortion map of known distortions in an operating environment is stored in the processor, and the processor is further adapted to correct for the known distortions using the distortion map.

20. The system of claim 19 wherein the processor is further adapted to detect the presence of known distortions in the environment and, in response to the detected presence, to automatically initiate use of the distortion map to correct for the known distortions.

21. The system of claim 19 wherein the distortion map is created by placing the field generator and field detector in the operating environment and determining electromagnetic fields at specific locations within the environment.

22. The system of claim 19 wherein the operating environment is inside an ambulance.

23. The system of claim 1 further comprising a second field detector for taking into account any motion or displacement of a non-rigid surface supporting the patient.

24. The system of claim 23 wherein a first one of the compound field detector, the second field detector and the field generator is adapted to move in accordance with the non-rigid surface, a second one of the compound field detector, the second field detector and the field generator is adapted to move in accordance with the chest of the patient, and a third one of the compound field detector, the second field detector and the field generator is adapted to be stationary relative to the patient.

25. The system of claim 24 wherein motion or displacement of the non-rigid surface is taken into account by determining the relative motion between the first one of the compound field detector, the second field detector and the field generator adapted to move in accordance with the non-rigid surface, and the second one of the compound field detector, the second field detector and the field generator adapted to move in accordance with the chest of the patient.

26. The system of claim 1 further comprising at least one of a force sensor and a pressure sensor provided with the position sensor.

27. The system of claim 26 wherein the processor is further adapted to correct for at least one of noise, distortion and hemisphere ambiguity in the position information using data from the at least one of the force sensor and the pressure sensor.

28. The system of claim 26 wherein the processor is further adapted to calculate a calibration constant for data from at least one of the force sensor and the pressure sensor using the position information.

29. The system of claim 28 wherein the calibration constant transforms the data from the at least one of the force sensor and pressure sensor into at least one of position data and depth data.

30. The system of claim 29 wherein the processor is further adapted to calculate the chest compression depth using the data from the at least one of the force sensor and the pressure sensor in the absence of position information.

31. The system of claim 30 wherein the system receives power from a power source, and the processor is further adapted to turn off power to the field generator and use the data from the at least one of the force sensor and the pressure sensor to conserve system power.

32. The system of claim 26 wherein the processor is further adapted to determine chest recoil using data from the force sensor.

33. The system of claim 1 further comprising an accelerometer provided with the reference sensor.

34. The system of claim 33 wherein the accelerometer is adapted to detect movement of the reference sensor.

35. The system of claim 34 wherein movement detected by the accelerometer is used to correct for any movement of the reference sensor.

36. The system of claim 1 wherein the processor is further adapted to receive chest impedance data and to use the chest impedance data to correct for any noise and distortion in the position information.

37. The system of claim 1 further comprising a housing within which the position sensor is removably contained.

38. The system of claim 37 wherein the removable housing is removable for performing CPR on an infant.

39. The system of claim 1 wherein the system comprises a feedback component for providing feedback to a CPR administrator based on at least one of the determined position information and the determined chest compression depth.

40. The system of claim 39 wherein the feedback comprises at least one of visual, audio, and tactile prompts.

41. The system of claim 1 wherein the reference sensor and the processor are provided in a base unit, and the position sensor is in communication with the base unit.

42. The system of claim 41 wherein a power source is provided in the base unit, and an auxiliary power source is provided with the position sensor.

43. The system of claim 41 wherein the base unit comprises a feedback component for providing feedback to a CPR administrator based on at least one of the determined position information and the determined chest compression depth.

44. The system of claim 43 wherein the feedback comprises at least one of visual, audio, and tactile prompts.

45. A method for determining a depth of compression of a chest of a patient receiving chest compressions, the method comprising:

determining the positions of at least two coils adapted to move in accordance with the chest;

estimating an apparent distance between the coils;

estimating a correction factor based on any differences between the apparent distance and a known distance between the coils; and

determining the chest compression depth based on the determined positions and the correction factor.

46. The method of claim 45 wherein the coils are provided in a compound field detector used in a system for determining chest compression depths, the system further comprising a field generator and a processor, wherein the coils are adapted to generate response signals in response to a field generated by the field generator, and wherein the processor is adapted to receive signals from the coils and to carry out the method using information represented by the received signals.

47. The method of claim 45 wherein the known distance is substantially parallel to a direction of chest compression.

48. The method of claim 45 wherein initial positions are defined for each coil at a given time, and determining the apparent distance is based a determination of apparent distance traveled by one of the at least two coils from its own initial position to an initial position of another one of the at least two coils.

49. A compound field detector for determining a depth of compression of a chest of a patient receiving chest compressions, the detector comprising:

at least two coils at a fixed distance from each other;

wherein the detector is adapted to generate a response signal indicative of any one of the at least two coils detecting a field.

50. The detector of claim 49, wherein each coil comprises windings, and the windings of each coil are substantially parallel to the windings of each other coil.

51. The detector of claim 49, wherein each coil comprises windings, each coil having a longitudinal axis perpendicular to a plane defined by the respective windings, wherein the longitudinal axis of each coil is substantially parallel with a direction of the chest compressions.

52. The detector of claim 49, further comprising a wire for coupling to a field generator.

53. The detector of claim 49, wherein the detector is further adapted to couple wirelessly to a field generator.

54. The detector of claim 50 further comprising at least one perpendicular field detecting coil having windings perpendicular to and surrounding the at least two parallel coils.

55. The detector of claim 50 wherein each parallel coil is surrounded by up to two perpendicular field detecting coils having windings perpendicular to the parallel coils and perpendicular to each other perpendicular coil.

56. The detector of claim 54 wherein the parallel coils share at least one common perpendicular coil.