A new technique for repeated measurement of cardiac output during cardiopulmonary resuscitation

The authors have developed a method for measurement of cardiac output during CPR with ventricular fibrillation. The method avoids the problems encountered when conventional techniques are used under the conditions of very low cardiac output. The method consists of injecting 5% saline as the indicator into the left ventricular and detecting its appearance in the descending aorta by withdrawing aortic blood through an electrically calibrated conductivity cell. The adequacy of indicator mixing has been verified by obtaining dilutions curves simultaneously from the brachial and femoral arteries. Cardiac output can be determined even when output is as low as 7 ml/min . kg during CPR with ventricular fibrillation. Repeated determinations can be made as often as every min. This method offers promise as a practical research tool which can also be used with dye indicators.