Role of Hypoxia in Hypothermic Cardiac Arrest in the Heart-Lung Preparation

Abstract

Starling s heart-lung preparation in the dog was modified to allow the direct measurement of total coronary flow according to the technique of Rodbard and subjected to hypothermia by cooling the blood. Cardiac arrest occurred by ventricular fibrillation in 10 experiments. In 10 other experiments arrest did not occur despite cooling to as low a temperature as possible (lowest S-A temperature 11.1[degree]C). Of the group in which arrest supervened, in 5 control experiments (air-inflation) the average S-A temperature that caused ventricular fibrillation was 19.6[degree]C, S.E. [plus or minus] 0.7, with a terminal coronary flow 27% greater than at the start of cooling, whereas with 100% O2 administration in which coronary flow was 36% more than the flow prior to cooling (blood pumped from venous reservoir into arterial circuit) an average temperature of 20.3[degree]C, S.E. [plus or minus] 0.5 was obtained (5 experiments.) It is concluded that hypoxia does not play a role in hypothermic arrest of heart by ventricular fibrillation.