Non-invasive intracranial monitor

• US 8,211,031 B2
• Filed: 12/14/2006
• Issued: 07/03/2012
• Est. Priority Date: 01/15/2002
• Status: Expired due to Fees

• Current Assignee: Orsan Medical Technologies, Ltd.
• Original Assignee: Orsan Medical Technologies, Ltd.
• Inventors: Poupko, Ben Zion, Reichman, Yosef, Rappaport, Alon, Ben-Ari, Shlomi
• Primary Examiner(s): Mallari, Patricia
• Assistant Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US11/610,553
• Publication Number:
  US 20070287899A1
• Time in Patent Office: 2,028 Days
• Field of Search: 600/383, 600/506, 600/553, 600/545, 600/547
• US Class Current: 600/506
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• 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 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/407 Evaluating the spinal cord A61B5/4896 takes precedence
• CPC Class Codes: A61B 5/4076 Diagnosing or monitoring particular conditions of the nervous system A61B5/4821, A61B5/4824 take precedence

Abstract

A method of estimating at least one intracranial hemodynamic parameter in a subject, the method comprising:

• • a) obtaining data of changes in electrical impedance across the subject'"'"'s head as a function of time;
  • b) analyzing the data; and
  • c) estimating one or more of intracranial pressure, cerebral blood volume, and a factor related to at least one of cerebral perfusion pressure and a mean transit time through cerebral capillaries.

Claims

1. A cranial diagnostic apparatus comprising:

at least one processor configured to;

receive impedance data indicative of electrical impedance measured via a subject'"'"'s head;

correlate the impedance data with a timing of at least a portion of a cardiac cycle;

identify in the data a first impedance characteristic correlated to the portion of the cardiac cycle;

identify in the data a second impedance characteristic correlated to the portion of the cardiac cycle;

compare the first impedance characteristic with the second impedance characteristic; and

estimate at least one intracranial hemodynamic parameter from the comparison of the first and the second impedance characteristics.

2. The apparatus of claim 1, wherein the hemodynamic parameter includes at least one of intracranial pressure, cerebral perfusion pressure, cerebral blood volume, and a mean transit time through cerebral capillaries.

3. The apparatus of claim 2, wherein the first impedance characteristic is reflective of a first local maximum impedance and wherein the second impedance characteristic is reflective of a second local maximum impedance.

4. The apparatus of claim 2, wherein the first impedance characteristic is reflective of a maximum rate of rise in impedance.

5. The apparatus of claim 2, wherein the first impedance characteristic is reflective of a maximum rate of fall in impedance.

6. The apparatus of claim 2, wherein the first impedance characteristic is reflective of a range of impedance between a minimum and a maximum.

7. The apparatus of claim 1, wherein the hemodynamic parameter includes intracranial pressure.

8. The apparatus of claim 1, wherein the at least one processor is further configured to remove variations in the data due to the subject'"'"'s breathing cycle.

9. The apparatus of claim 1, wherein the first impedance characteristic is reflective of a local maximum impedance.

10. The apparatus of claim 1, wherein the first impedance characteristic is reflective of a local minimum in rate of rise of impedance.

11. The apparatus of claim 1, wherein the first impedance characteristic is reflective of a maximum rate of rise of impedance and wherein the second impedance characteristic is reflective of a local maximum in impedance.

12. The apparatus of claim 1, wherein the first impedance characteristic is reflective of a maximum rate of rise of impedance and wherein the second impedance characteristic is reflective of a local minimum in rate of rise of impedance.

13. The apparatus of claim 1, wherein the at least one processor is further configured to normalize the data to a total range of impedance between a minimum and a maximum.

14. The apparatus of claim 1, wherein the first impedance characteristic is reflective of a latency time.

15. The apparatus of claim 1, wherein the at least one processor is further configured to average the estimate of the at least one intracranial hemodynamic parameter over a plurality of cardiac cycles.

16. The apparatus of claim 1, wherein identifying a first impedance characteristic includes averaging the data from a same phase of a plurality of cardiac cycles and wherein identifying a second impedance characteristic includes averaging the data from a same phase of a plurality of cardiac cycles.

17. The apparatus of claim 1, wherein the at least one processor is further configured to monitor the at least one intracranial hemodynamic parameter substantially continuously for a subject for a period of time.

18. The apparatus of claim 1, wherein the at least one processor is further configured to receive data indicative of the subject'"'"'s blood pressure.