Methods: Four-hundred and eighty-two consecutive patients who had undergone elective CABG were prospectively included in the study and divided into two groups: group 1 (n=260), patients who had high blood lactate levels in the first measurement (>3.5 mmol/l) in the intensive care unit (ICU); group 2 (n=222), patients who had normal blood lactate levels (<3.5 mmol/l). The duration of cardiopulmonary bypass (CPB) and cross-clamping (CC), hyperglycemia (blood glucose level >140 mg/dL), the presence of hemodynamic instability and requirement for vasopressors during CPB, inotropic agent administration for more than three hours and the temperature and lactate changes at five different time points during ICU stay were measured. Postoperative neurologic, infectious and renal complications and the durations of ICU stay and mechanical ventilation were recorded.

Results: The blood lactate levels were found significantly higher in patients with longer CPB and CC durations and peroperative hemodynamic instability. Postoperatively, the patients who had high glucose levels and high inotropic agent needs also had higher lactate levels. The patients in group 1 had longer extubation times and ICU stays. There was a significant correlation between blood lactate levels and mortality and morbidity (p<0.01).

Conclusion: Having an initial blood lactate concentration higher than 3.5 mmol/l after being transferred to ICU is a bad prognostic indicator. Serial lactate measurements may allow for detection of patients with high risk of developing mortality and morbidity and taking the necessary preventive measures.