Browse Prior Art Database

Blood Flow and Pressure Measurement

IP.com Disclosure Number: IPCOM000073777D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Horton, JW: AUTHOR

Abstract

This is a nonsurgical technique of measuring blood flow and pressure by injecting microscopic gas bubbles into the bloodstream of a patient and using ultrasonic radiating and detecting means.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 66% of the total text.

Page 1 of 2

Blood Flow and Pressure Measurement

This is a nonsurgical technique of measuring blood flow and pressure by injecting microscopic gas bubbles into the bloodstream of a patient and using ultrasonic radiating and detecting means.

The bubbles are formed by agitating a saline solution and a blood compatible gas containing a large amount of oxygen. 100 to 200 bubbles in the range of
0.001 to 0.01 centimeter in diameter are injected into the bloodstream.

In contact with the body surface 38 is an ultrasonic transmit-receive unit 39. A bubble 35 passing through a blood vessel 36, with the blood flow in the direction of arrow 37, is subjected to energy at or near its resonant frequency. As a result, waves 40 are scattered by the bubble.

To determine the speed of the bubble and consequently, the rate of the blood flow, a Doppler technique utilizing a right triangle ABC is used. The direction CA is first located, where A is the point of closest approach of the bubble as determined by echo ranging (sonar). Angle ACB is chosen conveniently and then angle CBA is known, since it is the complement of angle ACB. The signal scattered back by the bubble of frequency f1 is higher in frequency than the transmitted signal of frequency f. From a measurement of f1 - f = Delta f, the bubble speed in the vessel is given by the expression: v = c (Delta f/f) cosine Theta, where c is the velocity of sound and Theta is equal to angle CBA.

Blood pressure is obtained by subjecting the bubble to...