Author(s): Ananda Bhat, Perumala Ramanna Balajibabu, Chilukoori Raghu
BACKGROUND Blood lactate is a product of anaerobic metabolism. Tissue hypoxia because of hypo perfusion or impaired oxygen extraction causes rise in blood lactate levels. An elevated blood lactate level has been postulated as a marker for adverse outcomes and increased mortality risk in patients undergoing cardiac surgery under cardiopulmonary bypass (CPB). This study was carried out to evaluate the association between blood lactate levels and mortality following cardiac surgery. METHODS This retrospective record-based cross-sectional study was carried out among 503 patients who underwent cardiac surgery under CPB. Apart from baseline lactate value, serum lactate was measured every thirty minutes during CPB (CPBL1, CPBL2, CPBL3 and so on) and during post-operative period (POL1, POL2, POL3 and so on). Duration of the CPB, lowest temperature attained during the CPB, duration of mechanical ventilation, IABP usage, maximum number of inotropes and vasopressors used and mortality in the peri-operative period were noted. RESULTS The incidence of mortality in this study was 2.2%. Blood Lactate levels were high in the third measurement during CPB (CPBL3) and for all the post-operative measurements among those who did not survive. There was a significant association between lactate levels and intra operative lowest temperatures (p<0.05). CONCLUSIONS Lactate levels during CPB and post-operative period can be used as a predictor of increased mortality and morbidity. Prolonged bypass and deeper levels of hypothermia is associated with increased lactate levels.