Estimation of cardiac output in calves and sheep by the dye and Fick oxygen techniques

Cardiac output was estimated in calves and sheep by both the Fick dye (T-1824) and oxygen techniques. A method for aortic puncture was developed in order to obtain arterial blood. In 15 unanesthetized calves, the average cardiac output per kilogram, and the average cardiac index was 123 ml/kg/min. and 5.2 l/m2/min., respectively. In 11 calves anesthetized with pentobarbital sodium, the corresponding values were 118 ml/kg/min. and 4.5 l/m2/min. Comparable values in six anesthetized ewes were 126 ml/kg/min. and 3.8 l/m2/min. There was close agreement in nine individual comparisons between the results obtained with the dye and Fick oxygen methods.