Portable device for monitoring electrocardiographic signals and indices of blood flow

• US 20070021683A1
• Filed: 09/25/2006
• Published: 01/25/2007
• Est. Priority Date: 05/10/2004
• Status: Abandoned Application

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Transoma Medical, Inc.
• Inventors: Benditt, David, Lurie, Keith, Patterson, Robert
• Application Number:
  US11/526,956
• Publication Number:
  US 20070021683A1
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/6837 Sutures

Abstract

Embodiments of the present invention are directed to a physiological monitoring device which is configured to record signals that reflect blood flow and/or blood pressure, and which may also record ECG signals. In one embodiment, a portable monitoring device comprises a plurality of impedance electrodes configured to be coupled to a patient'"'"'s body and to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field, the local electrical impedance being a surrogate measure of local blood flow of the portion of the patient'"'"'s body. At least a portion of the portable monitoring device is configured to be insertable subcutaneously into the patient'"'"'s body.

Claims

1-36. -36. (canceled)

37. A method of monitoring a patient, the method comprising:

coupling a plurality of impedance electrodes to a patient'"'"'s body to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field, the local electrical impedance being a surrogate measure of local blood flow of the portion of the patient'"'"'s body which exhibits pulsation of blood corresponding to the local electrical impedance between the impedance electrodes; and

inserting at least a portion of a portable monitoring device including the impedance electrodes subcutaneously into the patient'"'"'s body.

38. The method of claim 37 wherein the impedance electrodes are placed in proximity to a target region of the patient'"'"'s body to be monitored.

39. The method of claim 38 wherein the impedance electrodes are placed within less than about 5 cm of the target region of the patient'"'"'s body to be monitored.

40. The method of claim 37 wherein the impedance electrodes are applied to a muscle of the patient'"'"'s body to be monitored.

41. The method of claim 37 further comprising positioning two of the impedance electrodes near an artery and spacing the impedance electrodes in a direction generally parallel to the artery.

42. The method of claim 37 further comprising positioning two of the impedance electrodes near an artery and spacing the impedance electrodes in a direction generally transverse across the artery.

43. The method of claim 37 further comprising measuring local tissue temperature of the patient'"'"'s body.

44. The method of claim 43 further comprising monitoring the measured local tissue temperature for an abrupt local temperature change as potential indication of an acute change in local blood flow.

45. The method of claim 37 further comprising measuring ECG data of the patient.

46. The method of claim 45 further comprising:

correlating the measured ECG data of the patient with the measured local electrical impedance of the patient as a surrogate measurement of blood flow.

47. The method of claim 37 further comprising transferring information obtained by the impedance electrodes to an external device disposed outside the patient'"'"'s body.

48. The method of claim 37 further comprising generating a warning based on the detected information.

49. The method of claim 37 further comprising storing physiological information obtained by detecting the local electrical impedance by the impedance electrodes.

50. The method of claim 49 wherein the physiological information is stored based on instructions delineating criteria for data to be stored.

51. The method of claim 49 wherein the physiological information is stored proximate to an event based on information detected by the impedance electrodes or patient-activated triggering.

52. The method of claim 37 further comprising coupling auxiliary leads to the impedance electrodes and positioning the auxiliary leads in a target location in the patient'"'"'s body.

53. The method of claim 37 wherein the portion of the patient'"'"'s body encompassed by the electrical field includes at least one of an artery, muscle, or tissue which exhibits pulsation of blood corresponding to the local electrical impedance between the impedance electrodes.

54. The method of claim 37 further comprising:

monitoring a change in the measured local impedance; and

obtaining a pulsatile blood volume change in the portion of the patient'"'"'s body encompassed by the electrical field based on the change in the measured local impedance.

55. The method of claim 54 wherein the change in the pulsatile blood volume change in the portion of the patient'"'"'s body encompassed by the electrical field is proportional to the change in the measured local impedance.

56. A method of monitoring a patient, the method comprising:

coupling a plurality of impedance electrodes to a patient'"'"'s body to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field;

monitoring a change in the measured local impedance; and

obtaining a pulsatile blood volume change in the portion of the patient'"'"'s body encompassed by the electrical field based on the change in the measured local impedance.

57. The method of claim 56 wherein the impedance electrodes are placed within less than about 5 cm of a target region of the patient'"'"'s body to be monitored.

58. The method of claim 57 wherein the impedance electrodes are placed within less than about 5 cm of an artery in the target region.

59. A method of monitoring a patient, the method comprising:

coupling a plurality of impedance electrodes to a patient'"'"'s body to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field, the local electrical impedance being a surrogate measure of local blood flow of the portion of the patient'"'"'s body;

measuring ECG data of the patient; and

correlating the measured ECG data of the patient with the measured local electrical impedance of the patient as a surrogate measurement of blood flow.

60. The method of claim 59 wherein the impedance electrodes are placed within less than about 5 cm of a target region of the patient'"'"'s body to be monitored.

61. The method of claim 60 wherein the impedance electrodes are placed within less than about 5 cm of an artery in the target region.