An Ensemble for Determination of Circulation Time of Blood By an Ionization (Geiger Chamber) Method

Abstract

A decade ago there appeared the first of a series of publications by Blumgart and his associates 1 concerning the use of injections of the disintegration products of radon (radium emanation) for the determination of the time elapsing between the introduction of the radioactive material at a given point in the blood-vascular system and its arrival at some other point in the system as detected by a shielded ionization chamber.

In the early investigations the radioactive material was injected into the cubital vein of one arm and detection of its arrival in the radial artery of the other arm was accomplished by means of a modification of the cloud-chamber devised by Wilson. 2 In the later studies Blumgart and his coworkers used ionization chambers of the type designed by Geiger 3 and a mechanism for recording the time of passage of the active material between the chosen points. The ensemble of apparatus was somewhat cumbersome, unwieldy and expensive. A compact, portable and relatively inexpensive type of equipment has been assembled and used by us in investigations concerning the circulation time of the blood between 2 points (in general, between the left jugular vein and the right femoral artery, lying in the adductor canal) and as an adjunct in the series of investigations concerning blood flow in dogs by Herrick, Essex, Mann and Baldes. 4 The apparatus and method have the advantages of absence of trauma, utilization in trained animals, deletion of reaction times and of immediate and positive detection of the injected radioactive material. By reason of the desire expressed by various investigators for information concerning the experimental ensemble and procedure, we are presenting the essential features.

The ensemble of apparatus for the detection and recording of the radioactive material at the time of its arrival at the chosen point in the blood-vascular system consists essentially of 4 parts: an ionization (Geiger) chamber and attached insulated cable, a supply of power of high voltage for the ionization chamber, three stages of amplification with power supplies, and a mechanism for recording the receipt of ionizing energy or changes in ionization in the Geiger chamber.