Lawrence Medical Systems, Inc.

Stephen R Barnes

Lee L Huntsman

Gary L Tarbox

Barry D McLaren

Richard S Leard

Gary L Nichols

Donald R Galer

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.

Methods and apparatus for monitoring cardiac output

An ultrasonic probe for insonifying the ascending aorta of a supine or reclining human patient. The probe has a head housing transducers for insonifying the patient's ascending aorta and for intercepting doppler-shifted energy reflected from the proximate and distal walls of the ascending aorta and from blood flowing through the aorta. The transducer head is integral with and extends below the handle of the probe, facilitating the manipulation of the probe and alignment of the beam of ultrasonic energy propagated by the probe relative to the ascending aorta of the patient. An oval cross-section and trapezoidal profile allow this to be done with a minimum of discomfort to either the patient or the user of the probe, and an L- or T-shaped handle allows the probe to be positioned and manipulated from a position behind the patient's head and with little or no sight of the patient's suprasternal notch.

Noninvasive ultrasonic probes

An ultrasonic transducer having a transducer head, for insonifying an organ or part thereof in a human patient from a position within the suprasternal notch thereof, wherein the transducer head is in at least a partially obscured disposition within the notch vis-a-vis the operator thereof during insonification, is comprised of an elongate handle member with a proximal and a distal end, having a non-circular peripheral cross-sectional geometry including at least one longitudinal edge to yield a gripping surface providing the operator with the ability to manipulate the probe via tactile sensing of its position and a transducer head extending from the distal end of, and generally normal to, the handle, wherein the head has a generally arcuate cross-sectional geometry and a generally trapezoidal profile to enhance patient comfort during operator manipulation of the probe.

Ultrasonic transducer probe

Hand held ultrasonic transducer for patient monitoring use

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.

Growing community of inventors

Seattle, WA, United States of America

Stephen R Barnes