Objective: To empirically derive the optimal measure of pharmacologic cardiovascular support in infants undergoing cardiac surgery with bypass and to assess the association between this score and clinical outcomes in a multi-institutional cohort.
Design: Prospective, multi-institutional cohort study.
Setting: Cardiac ICUs at four academic children's hospitals participating in the Pediatric Cardiac Critical Care Consortium during the study period.
Patients: Children younger than 1 year at the time of surgery treated postoperatively in the cardiac ICU.
Measurements and main results: Three hundred ninety-one infants undergoing surgery with bypass were enrolled consecutively from November 2011 to April 2012. Hourly doses of all vasoactive agents were recorded for the first 48 hours after cardiac ICU admission. Multiple derivations of an inotropic score were tested, and maximum vasoactive-inotropic score in the first 24 hours was further analyzed for association with clinical outcomes. The primary composite "poor outcome" variable included at least one of mortality, mechanical circulatory support, cardiac arrest, renal replacement therapy, or neurologic injury. High vasoactive-inotropic score was empirically defined as more than or equal to 20. Multivariable logistic regression was performed controlling for center and patient characteristics. Patients with high vasoactive-inotropic score had significantly greater odds of a poor outcome (odds ratio, 6.5; 95% CI, 2.9-14.6), mortality (odds ratio, 13.2; 95% CI, 3.7-47.6), and prolonged time to first extubation and cardiac ICU length of stay compared with patients with low vasoactive-inotropic score. Stratified analyses by age (neonate vs infant) and surgical complexity (low vs high) showed similar associations with increased morbidity and mortality for patients with high vasoactive-inotropic score.
Conclusions: Maximum vasoactive-inotropic score calculated in the first 24 hours after cardiac ICU admission was strongly and significantly associated with morbidity and mortality in this multi-institutional cohort of infants undergoing cardiac surgery. Maximum vasoactive-inotropic score more than or equal to 20 predicts an increased likelihood of a poor composite clinical outcome. The findings were consistent in stratified analyses by age and surgical complexity.