Metabolic Uncoupling Following Cardiopulmonary Bypass

ObjectiveThe objective of this study was to characterize the natural history of metabolic uncoupling (type B hyperlactemia and hyperglycemia) following cardiopulmonary bypass (CPB), and to determine the impact of insulin therapy on time to lactate normalization in patients without low cardiac output. DesignThe design used was a retrospective cohort study. SettingThe study was set in a pediatric cardiac intensive care unit in a tertiary-care urban children's hospital. PatientsAll patients were aged 21 years admitted between 2007 and 2013 following cardiac surgery involving CPB with empiric intraoperative corticosteroids. Eligibility criteria: simultaneous hyperlactemia (3.5mEq/L) and hyperglycemia (200mg/dL) within 48 hours after bypass. Exclusion criteriaExclusion criteria were evidence of low cardiac output state, diabetes or postoperative steroid administration. InterventionsCharacteristics were compared between those treated with insulin and those who were not (controls). Outcome MeasuresOutcome measures used were time from admission to onset of hyperglycemia and hyperlactemia and time to resolution. Clinical outcomes included duration of mechanical ventilation, length of stay, unplanned readmission/reoperation, hypoglycemia and death. ResultsOf the 1345 patients receiving CPB, 132 (9.8%) met inclusion criteria. Seventy-eight (59%) were treated with insulin, leaving 54 controls. Patient characteristics, surgical complexity and time to onset of hyperglycemia and hyperlactemia were similar between groups. The insulin group had a shorter duration of hyperglycemia. There was no significant difference between groups in time to lactate normalization, ventilator days, length of stay, readmission and reoperation rates. Hypoglycemia (<60mg/dL) occurred in three patients. ConclusionsIn children with metabolic uncoupling after CPB, insulin use did not shorten the time to lactate normalization or alter clinical outcomes. These findings suggest that type B hyperlactemia with hyperglycemia after CPB will resolve spontaneously and does not warrant specific treatment.