Challenging current evidence: Peripheral perfusion index fails as a predictor of postinduction hypotension – Findings from a large diverse surgical population

BACKGROUND: Postinduction hypotension (PIH) is a common complication of general anesthesia with potential clinical consequences. A recent meta-analysis suggested that the peripheral perfusion index (PPI) has a high predictive value for PIH. However, this was limited by small sample sizes and significant heterogeneity. We aimed to evaluate the predictive performance of preinduction PPI for PIH in a large surgical cohort. METHODS: In this retrospective single-center study, we analyzed 6653 adult patients who had general anesthesia between May 2022 and May 2023. PIH was defined as mean arterial pressure < 65 mmHg within 20 min after induction. We assessed the predictive performance of preinduction PPI for estimating PIH using the area under the receiver operating characteristic curve (AUC). A multivariable logistic regression was conducted to identify independent predictors of PIH. RESULTS: The overall incidence of PIH was 51.5 %. Preinduction PPI values were similar between patients who developed PIH and those who did not (1.22 [0.69-2.23] vs. 1.23 [0.75-2.13], P = 0.284). PPI demonstrated poor predictive performance for PIH (AUC 0.51, 95 % CI 0.49-0.52), with low sensitivity (31 %) and modest specificity (72 %) at the optimal cutoff (0.81). This poor discrimination persisted across all postinduction time intervals and patient subgroups. In contrast, independent predictors of PIH included preinduction mean arterial pressure, advanced age, higher ASA physical status, and emergency surgery. CONCLUSION: Despite promising results from smaller studies, we found that preinduction PPI had no significant predictive value for PIH in a large, diverse surgical population. Anesthesiologists should focus on established risk factors rather than PPI when assessing PIH risk.