Frequency and outcomes of severe hyperlactatemia after elective cardiac surgery

Background Hyperlactatemia is relatively common in the cardiac surgical patient and is usually considered a marker of illness severity. The frequency and impact of severe hyperlactatemia after elective cardiac surgery has not been described, and prognosis may be different compared with that for other surgical or medical critically ill patient populations. Methods We conducted a retrospective study to evaluate the hospital course and outcomes of patients who developed severe postoperative hyperlactatemia (SPHL; lactate >10 mmol/L) after elective cardiac surgery, from January 1, 2008 to December 31, 2012, at a large, academic, tertiary referral center. Results Of 9580 cardiac surgical patients who met inclusion criteria, 121 (1.26%) developed SPHL. The most common cause was cardiogenic shock (53.8%). In-hospital mortality was 40.5% but varied widely based on the cause of the SPHL. All patients with definite mesenteric ischemia (n = 5) or extremity compartment syndrome (n = 6) at the time of SPHL died in the hospital. Forty patients (33.1%) were discharged to home, whereas 32 (26.4%) were discharge to a skilled-care facility. Conclusions Severe postoperative hyperlactatemia is rare after elective cardiac surgery. Although this phenomenon continues to be associated with mortality, >50% of patients survived to hospital discharge, a more favorable prognosis, compared with other patient populations based on lactate levels alone. Important exceptions were patients who had extremity compartment syndrome or mesenteric ischemia, which were associated with in-hospital death in all cases. In all other etiologic groups, a substantial proportion of patients were discharged to home.