A comparison of cardiac output determined by the Fick procedure and a direct method using the rotameter.

Experiments were performed on the anesthetized dog to determine the accuracy of the widely used Fick procedure. Cardiac output values, recorded by an optical rotameter, served as a reliable standard for comparison. Under the conditions of these experiments, comparisons showed excellent agreement. The average variation between the two series of the measurements was ±5 per cent. Twelve of thirteen comparisons agreed within less than ±8 per cent. This small deviation was within the range of error which might have existed on the basis of known technical inaccuracies.