Metabolic Uncoupling Following Cardiopulmonary Bypass.

OBJECTIVE: The 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.

DESIGN: The design used was a retrospective cohort study.

SETTING: The study was set in a pediatric cardiac intensive care unit in a tertiary-care urban children's hospital.

PATIENTS: All patients were aged ≤21 years admitted between 2007 and 2013 following cardiac surgery involving CPB with empiric intraoperative corticosteroids.

ELIGIBILITY CRITERIA: simultaneous hyperlactemia (≥3.5 mEq/L) and hyperglycemia (≥200 mg/dL) within 48 hours after bypass.

EXCLUSION CRITERIA: Exclusion criteria were evidence of low cardiac output state, diabetes or postoperative steroid administration.

INTERVENTIONS: Characteristics were compared between those treated with insulin and those who were not (controls).

OUTCOME MEASURES: Outcome 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.

RESULTS: Of 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 (<60 mg/dL) occurred in three patients.

CONCLUSIONS: In 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.