Oxygen transport in critically ill infants after congenital heart operations

Background. Oxygen transport variables reflect the balance of oxygen delive ry and demand. Because oxygen transport in infants undergoing congenital ca rdiac operations is not well described, we examined oxygen transport in suc h patients. Differences in oxygen transport between survivors and nonsurviv ors and variables that might be predictive of outcome were sought. Methods. We reviewed hospital records of infants admitted to the pediatric cardiac intensive care unit in our institution from January 1996 through Ap ril 1997. Infants in whom simultaneous arterial blood gas and systemic veno us oxygen saturation measurements were performed on admission and at 6 and 24 hours after admission were included. Analyses of arterial pH, base exces s, arteriovenous oxygen saturation differences, and oxygen extraction ratio were performed, including comparisons of survivors and nonsurvivors and ch anges over time. Results. Forty-nine infants were included in the study, with 39 survivors. There were no differences in any parameter between survivors and nonsurvivo rs on admission or at 24 hours. At 6 hours, differences between survivors a nd nonsurvivors were significant for arterial pH (7.48 versus 7.35, p < 0.0 01), base excess (2.9 versus -4.3 mmol/L, p < 0.01), arteriovenous oxygen s aturation difference (34 versus 43, p < 0.05), and oxygen extraction ratio (0.28 versus 0.53, p < 0.001). The oxygen extraction ratio at 6 hours was a t least 0.5 in 6 of 39 survivors and 7 of 10 nonsurvivors (p = 0.002). Conclusions. Infants who die after cardiac operations have significant dera ngements of oxygen transport at 6 hours after admission to the intensive ca re unit. Infants with an oxygen extraction ratio greater than 0.5 at 6 hour s are at highest risk. (Ann Thorac Surg 1999;67:739-44) (C) 1999 by The Soc iety of Thoracic Surgeons.