The Impact of Intraoperative Hyperlactatemia on Weaning from Cardiopulmonary Bypass in Patients Undergoing on-Pump Coronary Artery Bypass Grafting Surgery: An Observational Study

Abstract

Background: Hyperlactatemia after cardiac surgery is common. However, the association and the implications of hyperlactatemia on the prognosis after cardiopulmonary bypass (CPB) remains controversial. This study investigated the associations between early-onset hyperlactatemia and the need for doses of inotropes and vasopressors during weaning from CPB, hemodynamic stability after weaning from CPB, and the duration of postoperative mechanical ventilation. Patients and Methods: This prospective cohort study included 300 patients who underwent elective on-pump coronary artery bypass grafting (CABG) surgery and had normal systolic function >55%. Serum lactate levels were measured 1 h before induction, upon initiation of CPB, after removal of aortic cannula and on admission to the intensive care unit (ICU). Patients were divided into two groups: patients with lactate levels <4 mmol/L (Group N) and those with lactate levels ≥4 mmol/L (Group H). Results: Patients with hyperlactatemia constituted 20.7% of the study population. The number of patients who required adrenaline and noradrenaline administration upon weaning from CPB, as well as the doses of these drugs, were significantly higher in Group H (P < 0.001). Arterial blood pressure levels after weaning from CPB and upon admission to the ICU were significantly lower in Group H patients (P < 0.001). The duration of post-operative mechanical ventilation was longer in Group H patients (P < 0.001). Conclusion: Early-onset hyperlactatemia was associated with worse outcomes after CABG surgery. There was difficult weaning from CPB with increased inotrope and vasopressor drug support, early post-operative hemodynamic instability, and a prolonged duration of post-operative mechanical ventilation.