A Clinical Mathematical Model Estimating Postoperative Urine Output in Children Underwent Cardiopulmonary Bypass for Congenital Heart Surgery

Objectives: To build a proof of concept clinical mathematical model estimating postoperative urine output (UOP) utilizing pre-operative, intra-operative and immediate postoperative variables in children underwent cardiopulmonary bypass (CPB) for congenital heart surgery. Methods: Single-center, retrospective cohort study in a university-affiliated children’s hospital. Patients younger than 21 years old who underwent CPB for congenital heart surgery and were postoperatively admitted to West Virginia University Children’s Hospital`s pediatric intensive care unit (PICU) between September 1, 2007, and June 31, 2013 were included in the study. Body surface area, CPB duration, first measured hematocrit, serum pH, central venous pressure and vasoactive-inotropic score in the PICU were used to build the mathematical model. A randomly selected 50% of the dataset was used to calculate model parameters. A cross validation was used to assess model performance. Results: A total of 256 patients met inclusion criteria. The model was able to achieve mean absolute error of 1.065 ml/kg/hr (95% Confidence Interval (CI): 1.062-1.067 ml/kg/hr), root mean squared error of 1.80 ml/kg/hr (95% CI: 1.799- 1.804 ml/kg/hr) and R2 of 0.648 (95% CI: 0.646-0.650) in estimating UOP in the first 32 hours of postoperative period. Conclusions: The mathematical model utilizing pre-operative, intra-operative and immediate postoperative variables may be a potentially useful clinical tool in estimating UOP in the first 32 hours postoperative period.