Correlation between Post-operative Serum Lactate Levels and Low Cardiac Output Syndrome in Patients Undergoing Coronary Artery Bypass Grafting Surgery: A Prospective Study in a Tertiary Care Hospital

Objectives: This study aimed to assess the correlation between the development of low cardiac output syndrome (LCOS) and post-operative serum lactate levels in patients undergoing coronary artery bypass grafting (CABG) surgery at a tertiary care hospital. Methodology: A prospective cross-sectional study was conducted from January to June 2021, involving 50 patients undergoing CABG surgery with cardiopulmonary bypass. Arterial samples were obtained immediately post-surgery and at six, twelve, and twenty-four-hour intervals post-operatively. The association between lactate levels and the occurrence of LCOS, need for inotropic support, and intra-aortic balloon pump (IABP) utilization was evaluated. Results: The study comprised predominantly male patients (84%). Patients were categorized into two groups based on lactate levels: Group 1 (> 4 mmol/L) and Group 2 (< 4 mmol/L). In Group 1, 32% of patients developed LCOS, 10% required IABP, and 20% needed inotropic and vasopressor support. Immediately post-CABG, the mean lactate level was 7.5 mmol/L, with 3% requiring IABP and 20% needing double inotropic support. Lactate levels decreased over time, with mean levels at six, twelve, and twenty-four hours post-surgery being 6.3 mmol/L, 3.8 mmol/L, and 3.3 mmol/L, respectively. Correspondingly, the need for IABP and inotropic support decreased. LCOS occurrence within 24 hours post-surgery correlated significantly with elevated lactate levels (p < 0.05). Conclusion: Elevated lactate levels were associated with the development of LCOS within 24 hours post-CABG surgery. Monitoring lactate levels postoperatively may serve as a valuable tool in predicting and managing LCOS in CABG patients.