Shock Index, Coronary Perfusion Pressure, and Rate Pressure Product As Predictors of Adverse Outcome After Pediatric Cardiac Surgery

Abstract

Objectives: To determine whether shock index, coronary perfusion pressure, or rate pressure product in the first 24 hours after congenital heart surgery are independent predictors of subsequent clinically significant adverse outcomes.

Design: A retrospective cohort study.

Setting: A tertiary care center.

Patients: All patients less than 18 years old who underwent cardiac surgery at Boston Children's Hospital between January 1, 2010, and December 31, 2018.

Interventions: None.

Measurements and main results: Shock index (heart rate/systolic blood pressure), coronary perfusion pressure (diastolic blood pressure-right atrial pressure), and rate pressure product (heart rate × systolic blood pressure) were calculated every 5 seconds, and the median value for the first 24 hours of cardiac ICU admission for each was used as a predictor. The composite, primary outcome was the occurrence of any of the following adverse events in the first 7 days following cardiac ICU admission: cardiopulmonary resuscitation, extracorporeal cardiopulmonary resuscitation, mechanical circulatory support, unplanned surgery, heart transplant, or death. The association of each variable of interest with this outcome was tested in a multivariate logistic regression model. Of the 4,161 patients included, 296 (7%) met the outcome within the specified timeframe. In a multivariate regression model adjusted for age, surgical complexity, inotropic and respiratory support, and organ dysfunction, shock index greater than 1.83 was significantly associated with the primary outcome (odds ratio, 6.6; 95% CI, 4.4-10.0), and coronary perfusion pressure greater than 35 mm Hg was protective against the outcome (odds ratio, 0.5; 0.4-0.7). Rate pressure product was not found to be associated with the outcome. However, the predictive ability of the shock index and coronary perfusion pressure models were not superior to their component hemodynamic variables alone.

Conclusions: Both shock index and coronary perfusion pressure may offer predictive value for adverse outcomes following cardiac surgery in children, although they are not superior to the primary hemodynamic variables.