Publication:

Perioperative serum lactate as a predictor of postoperative morbidity and mortality in major abdominal surgery: a prospective observational study

Background Major abdominal surgery carries significant postoperative morbidity and mortality, driven by tissue hypoperfusion and metabolic derangement. Serum lactate, a sensitive marker of anaerobic metabolism, is a recognised prognostic indicator in surgical and critically ill patients. This study evaluated perioperative serum lactate as a predictor of in-hospital mortality and morbidity in major abdominal surgery.

Methods This prospective observational cohort study was conducted in the Department of General Surgery, R.N.T. Medical College, Udaipur, over one year. Sixty consecutive adults (18–80 years) undergoing elective or emergency major abdominal surgery were enrolled. Arterial lactate was measured preoperatively (L0), at 12 hours (L1) and 24 hours (L2). Complications were graded by Clavien-Dindo. ROC analysis, Mann-Whitney U, Chi-square and logistic regression were applied.

Results Among 60 patients (55.0% male; mean age 47.6±17.8 years), morbidity was 43.3% (n=26) and mortality 15.0% (n=9). Lactate differed significantly between survivors and non-survivors at all three time points (p < 0.001). L2 best predicted mortality (AUROC 0.993; 95% CI 0.956–1.000) at a 2.35 mmol/l cut-off (sensitivity 100%, specificity 96.1%, PPV 81.8%, NPV 100%). Mildly elevated L0 (2–4 mmol/l) carried 22-fold higher odds of death (OR=22.0; 95% CI 3.4–141.2; p=0.001). On regression, L2 was the strongest predictor (OR=18.24; p=0.002), followed by L1 (OR=6.82; p=0.008).

Conclusions The 24-hour postoperative serum lactate is a near-perfect predictor of in-hospital mortality in major abdominal surgery, with a validated cut-off of 2.35 mmol/l. Routine three-point perioperative serum lactate monitoring is strongly recommended as a cost-effective tool for early risk stratification in patients undergoing major abdominal surgery, particularly in resource-limited tertiary care settings.