Duration and magnitude of vasopressor support predicts poor outcome after infant cardiac operations

Background The vasoactive inotrope score (VIS) is a sum of the total vasopressor dose at a single point in time. Incorporating duration and magnitude of vasopressor requirements during the postcardiac surgical period could improve VIS sensitivity for predicting poor outcome. Methods This is a retrospective review of 244 infants (aged ≤365 days) who underwent cardiopulmonary bypass during congenital cardiac operations from 2002 to 2011. The VIS was calculated hourly for the first 72 hours. Poor outcome was defined as prolonged mechanical ventilation (≥6 days) or intensive care length of stay (≥12 days). First, the association between the maximum VIS (maxVIS) in the first 48 postoperative hours and poor outcome was confirmed for our study population. Next, postoperative intervals and VIS values that were significantly associated with poor outcome were identified and incorporated into a formula, termed the VISindex, which was compared with the traditional maxVIS. Results The VISindex demonstrated improved sensitivity for predicting prolonged mechanical ventilation (VISindex: area under the curve [AUC], 0.85; 95% confidence interval [CI], 0.79 to 0.90; maxVIS: AUC, 0.80; 95% CI, 0.75 to 0.86) and intensive care unit length of stay (VISindex: AUC, 0.84; 95% CI, 0.79 to 0.89; maxVIS: AUC, 0.77; 95% CI, 0.71 to 0.83) after cardiac operations in infants. Conclusions Incorporating magnitude and duration of postoperative vasopressor support into the VIS improves its sensitivity for predicting poor outcome.