A New Agent for Objective Measurement of Circulation Time

Abstract

The arm-to-head circulation time may be objectively measured by the injection of 1 cc of aminophylline (0.24 mg) into the antecubital veins. The end-point of the reaction is signalled most frequently by a marked increase in the depth of inspiration, which in many cases amounts to a gasp. While this occurs in every case, in some instances it may be preceded by swallowing movements, a change in facial expression resulting from subjective sensations, or a sharp catch during expiration. The first observable change is taken as the end-point. The test was tried in 92 patients at various stages in the postoperative state whose ages ranged from 12 to 82 years. Only once in 92 trials was any difficulty experienced in recognizing the end-point. The circulation times ranged from 7.1 to 20.4 seconds averaging 12.4 seconds. The test is safe, the end-point is sharp, the method is objective, the amount injected is small, the agent is readily accessible. All of these factors combine to commend it.