Date of Award

7-22-1968

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Medical

First Advisor

J.P. Kampine

Second Advisor

E.O. Henschel

Third Advisor

R.C. Meade

Abstract

There are in general two different methods used for measuring regional blood flows; the direct and the indirect methods.

The direct methods either involve the use of direct volume metering devices such as rotameters and droprecorders or are based upon measurement of some alteration in physical characteristics of flowing blood which are related to changes in 1-inear velocity of blood flow, examples of the latter include the ultrasonic and electromagnetic methods of measuring blood flow. The principle of the electromagnetic flowmeter introduced by Kolin is that when a conductor of electricity is moved through a magnetic field, a potential difference is created in the conductor, and this potential difference will be directly proportional to the number of magnetic lines of force cut per unit of time. This potential difference can be recorded and calibrated in terms of flow rate.

Indirect methods (except for venous occlusion plethysmography) are in general based on either of two principles. The first of these is the indicator dilution method based on the Steward Hamilton principles and best exemplified by dye, thermal or radioisotope dilution techniques. The second type of indirect blood flow method is the clearance method based on exclusive removal of indicator substance by a specific organ. The present standard PAH method described by Homer Smith has been the most widely used method for measuring renal blood flow. This method is based on the renal clearance principle. The term renal clearance was first used by Moller, McIntosh and Van Slyke and extended by Jolliffe and Smith. It may be defined as a quantitative description of the rate at which the kidney excretes various substances relative to their concentration in the plasma. Renal clearance C = UV/P, in which U is the urinary concentration in mg. per ml., V is the minute urine volume and Pis the plasma concentration in mg. per ml.

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