The impact of hyperlactatemia on postoperative outcome after adult cardiac surgery

Purpose To evaluate the value of blood lactate value in predicting postoperative mortality (primary outcome), duration of ventilation, and length of stay in an intensive care unit (ICU) and hospital (secondary outcomes). Methods We performed a prospective observation study on 1,820 consecutive patients undergoing open heart surgery in a tertiary university medical center. Blood lactate levels were obtained from patients on admission to the cardiac surgical ICU and measured serially. Results All patients were divided into three groups according to their maximum blood lactate levels: group I (normolactatemia, lactate ≤2.2 mmol/l), 332 patients; group II (mild hyperlactatemia, lactate 2.2-4.1 mmol/l), 1,054 patients; and group III (severe hyperlactatemia, lactate ≥4.4 mmol/l), 434 patients. Maximum blood lactate levels ≥4.4 mmol/l during the first 10 h post admission were associated with prolonged ventilation time, longer ICU stay, and increased mortality (P <0.001). Conclusions Hyperlactatemia is common after cardiac surgery. Maximal lactate threshold ≥4.4 mmol/l in the first 10 h after operation accurately predicts postoperative mortality.