Barry D Mclaren

US Patent:

47966343, Jan 10, 1989

Filed:

Aug 9, 1985

Appl. No.:

6/763992

Inventors:

Lee L. Huntsman - Bainbridge Island WA
Richard S. Leard - Issaquah WA
Gary L. Tarbox - Bainbridge Island WA
Stephen R. Barnes - Seattle WA
Barry D. McLaren - Auburn WA

Assignee:

Lawrence Medical Systems, Inc. - Camarillo CA

International Classification:

A61B 1000

US Classification:

12866201

Abstract:

A method and apparatus for ascertaining the cardiac output of a human patient, said method comprising the steps of: measuring the systolic velocity of the blood flowing through the patient's descending aorta; determining the cross-sectional area of the patient's ascending aorta; and calculating the patient's cardiac output from said systolic velocity and said aortic area. The cardiac output can be converted: (1) to cardiac index by dividing it by the patient's body surface area, and (2) to systemic vascular resistance by dividing a value representing the patient's blood pressure by said cardiac output.

US Patent:

45095264, Apr 9, 1985

Filed:

Feb 8, 1983

Appl. No.:

6/464965

Inventors:

Stephen R. Barnes - Seattle WA
Gary L. Tarbox - Seattle WA
Lee L. Huntsman - Bainbridge Island WA
Barry D. McLaren - Auburn WA

Assignee:

Lawrence Medical Systems, Inc. - Redmond WA

International Classification:

A61B 1000

US Classification:

128663

Abstract:

A method and system for the noninvasive measurement of cardiac output of a mammalian patient on a real time, beat-by-beat basis as a combined function of the cross-sectional area of the ascending aorta and the systolic velocity of blood flow therethrough is comprised of the steps of and apparatus for pulsedly insonifying the ascending aorta of the patient with repetitive, intermittent ultrasonic energy propagating through the patient's cardiac window; receiving pulses of ultrasonic energy reflected from the anatomical structure within the first insonification zone, including energy reflected from the aortic walls and characteristic of the dimensional separation thereof; developing an aortic diameter signal indicative of dimensional separation; computing the cross-sectional area of the ascending aorta therefrom; then continuously insonifying the ascending aorta with uninterrupted ultrasonic energy; receiving a Doppler-shifted ultrasonic energy signal reflected from pulsatile blood flow through the ascending aorta, and characteristic of systolic velocity of blood flow; subjecting the systolic velocity signal to a frequency spectrum analysis at a predetermined signal sampling rate to yield a velocity component profile signal; integrating the velocity component profile signal over time; computing systolic volume as a combined function of cross-sectional area and the systolic velocity integral for each of n cardiac cycles; and, computing cardiac output as the time-averaged sum of systolic volumes for the n periods.