Non-invasive measurement of suprasystolic signals

• US 7,727,157 B2
• Filed: 01/10/2006
• Issued: 06/01/2010
• Est. Priority Date: 09/13/2002
• Status: Active Grant

• Current Assignee: Uscom Ltd.
• Original Assignee: Nigel E. Sharrock
• Inventors: Sharrock, Nigel E.
• Primary Examiner(s): Marmor, II; Charles A
• Assistant Examiner(s): Natnithithadha; Navin
• Application Number:
  US11/328,822
• Publication Number:
  US 20060178585A1
• Time in Patent Office: 1,603 Days
• Field of Search: 600/481, 600483-486, 600/488, 600490-507, 600/513
• US Class Current: 600/495
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis

Abstract

An apparatus for assessing cardiovascular status of a mammal comprises a system for locally applying a pressure to an artery capable of restricting blood flow through said artery, a wideband external pulse transducer having an output and situated to measure suprasystolic signals proximate to said artery, and a computing device receiving said output for calculating vascular compliance values. The method described is particularly useful for determining cardiac output, assessing whether a pregnant female has preeclampsia or a patient has cardiac insufficiency, or assessing cardiac arrhythmia.

Claims

1. An apparatus for assessing a cardiovascular system of a mammal comprising:

a cuff for occluding systolic blood flow through a brachial artery of the mammal;

a transducer having an electronic output signal representing a suprasystolic blood pressure waveform in tissue subject to a blood flow occlusion by said cuff; and

a computing device receiving said output signal, analyzing a temporal and amplitude variation thereof, and determining a value representing large arterial vascular compliance in the mammal.

2. The apparatus of claim 1, wherein said computing device analyzes a change in arterial compliance with respect to differing conditions of the mammal.

3. The apparatus of claim 2, wherein said temporal and amplitude variation comprises a series of adjacent amplitude peaks and related dips, and the computing device calculates a first ratio of (1) the amplitude difference of a first peak and a subsequent dip and (2) the amplitude difference of a second peak and the subsequent dip.

4. The apparatus of claim 3, wherein the computing device calculates said value as a function of the natural logarithm of said ratio or a power function of said ratio.

5. The apparatus of claim 1, wherein the computing device assesses whether a pregnant mammal has a preeclampsia condition.

6. The apparatus of claim 1, wherein the computing device assesses whether a pregnant mammal has cardiac insufficiency.

7. The apparatus of claim 1, wherein the computing device determines stroke volume.

8. The apparatus of claim 1, wherein the computing device determines breathing efficacy.

9. The apparatus of claim 1, wherein said computing device calculates a cardiac output.

10. The apparatus of claim 1, wherein said transducer comprises a foil electret transducer.

11. The apparatus of claim 1, wherein said transducer comprises a piezoelectric transducer.

12. The apparatus of claim 11, wherein said transducer comprises an electromechanically responsive polymer film.

13. The apparatus of claim 1, wherein the arterial compliance is computed periodically.

14. The apparatus of claim 1, further comprising a computer readable storage medium, for storing instructions to control a processor in said computing device.

15. The apparatus of claim 1, wherein said transducer is disposed in said cuff, adjacent to tissue of the mammal.