Mortality after neonatal cardiac surgery: Prediction from mean arterial pressure after rewarming in the operating room.

OBJECTIVE: To examine the predictive contribution of mean arterial pressure after rewarming to > or =34 degrees C in the operating room to mortality after cardiac surgery in infants < or =6 weeks old.
METHODS: In this prospective inception cohort study, 70 consecutive infants who had open cardiac surgery with deep hypothermic circulatory arrest when < or =6 weeks old in the years 1996 to 1999 had follow-up to 5 years of age. Demographic, preoperative, operative, and postoperative variables were recorded prospectively. The previously unexplored variables of lowest mean arterial pressure in the operating room after rewarming to 34 degrees C were recorded retrospectively from anesthesia records. Predictor variables for death were examined using univariate and multivariate analyses.
RESULTS: Deep hypothermic circulatory arrest time, re-cardiopulmonary bypass in the operating room, duration of mean arterial pressure below 40, 35, 30, and 25 mm Hg after rewarming in the operating room, time for lactate to return to < or =2 mmol/L postoperatively, and cardiopulmonary resuscitation were significantly associated with death at 1 and 5 years of age on univariate analysis. Multivariate stepwise forward logistic regression analysis found the duration of mean arterial pressure after rewarming below 30 mm Hg (odds ratio 1.094; 95% confidence interval 1.033-1.158) and cardiopulmonary resuscitation (odds ratio 13.800, 95% CI 3.062-62.194) were significant predictors of death by 5 years of age. Stepwise multiple regression using pre- and intraoperative variables accounted for 30.1% of the variability related to mean arterial pressure < or =30 mm Hg after rewarming.
CONCLUSION: In these infants, low mean arterial pressure after rewarming in the operating room, even for brief times, is significantly associated with death.