Oxygen consumption in infants and children during cardiac catheterization under different sedation regimens

Oxygen consumption was measured in 426 infants and children during cardiac catheterization using an open circuit, flow through technique. Since this method does not require the cooperation of the patient, determinations were readily made in 170 infants. The purpose of this study was to determine those factors which significantly influence oxygen consumption and to determine the potential errors incurred in using predictive equations for estimating oxygen consumption. The type of sedation or anesthesia given was found to be one of the most important variables influencing oxygen consumption; therefore patients were classified into 5 anesthetic groups. Stepwise regression analysis revealed that each group had a distinctive set of hemodynamic or physical factors which significantly affected oxygen consumption; hence each group required a different predictive equation. Body size in terms of surface area or weight was the only significant variable common to all 5 patient groups. Using the predictive equations the estimated values differed from measured values by more than 20% in approx. one fifth of the cases. These data indicate that frequently oxygen consumption cannot be accurately estimated from predictive equations. Therefore if blood flow is to be accurately determined by the Fick method in infants and children, oxygen consumption should be measured during the catheterization procedure.