A New Technique for Obtaining Values of Cardiac Output in Rapid Succession

Cardiac output was measured in dogs using 5 percent saline as the indicator and a new type of electrically calibrated catheter-tip conductivity cell in the aorta. Paired values of cardiac output were compared using the direct Fick method. It was found that saline cardiac outputs overestimated the Fick values by about 15 percent on the average. Use of the electrically calibrated catheter-tip conductivity cell in the aorta is very easily applied; it does not require special preparation of the indicator or mixing calibration solutions and does not require withdrawal of blood. Cardiac output measurements can be made every few minutes.