Peripheral perfusion index versus serum lactate levels as predictor of postoperative complications after lengthy adult noncardiac surgery: a prospective observational study

Prolonged surgical procedures are associated with an increased risk of postoperative complications due to tissue hypoperfusion. Goal-directed fluid therapy and stroke volume optimization are strategies to maintain tissue perfusion, but their effectiveness is controversial. Peripheral Perfusion Index (PPI) and serum lactate level (SLL) are emerging parameters to assess tissue perfusion. This study aimed to compare the ability of PPI and SLL in early predicting postoperative complications in long adult noncardiac surgeries. This prospective, single-center study included 235 adult patients undergoing elective adult noncardiac surgery lasting more than 120 minutes. PPI and SLL were measured intraoperatively and postoperatively. Data on intraoperative variables and postoperative outcomes were collected. Of 235 patients, 65 (27.66%) had complications. The results showed that PPI was an earlier indicator of postoperative complications than SLL; the value was significantly lower in the complication group from the second hour intraoperatively. PPI showed superior predictive performance over SLL for postoperative complications, with AUC values increasing over time. Postoperative PPI measurements at 24 hours showed an AUC of 0.951 (P<0.001), with 96.92% sensitivity and 90.59% specificity at a cutoff of ≤1.4. SLL showed predictive ability, with the highest AUC of 0.932 (P<0.001) observed 48 hours after ward admission. Postoperative PPI and SLL measurements are promising predictors of postoperative complications in major adult noncardiac surgery. PPI shows superior predictive compared to SLL, indicating its potential utility in clinical practice for early detection of complications and optimization of patient outcomes.