Perfusion Index as a Predictor of Hypotension Following Spinal Anesthesia in Lower Segment Caesarean Section

Abstract

Objective: To assess the diagnostic accuracy of preoperative pulse oximetry-derived Perfusion Index (PI) as a non-invasive tool for predicting spinal anesthesia-induced hypotension in parturients undergoing elective lower segment cesarean section (LSCS). Study Design and Setting: Cross-sectional study, Department of Anesthesia, PAF Hospital Islamabad / Fazaia Medical College, from September 2022 to March 2023. Methodology: A total of 120 healthy parturients (ASA I–III, aged 16–38 years) listed for elective LSCS under spinal anesthesia were included through consecutive sampling. Participants were grouped into Group A (High PI more than or equal to 3.5, n=60) or Group B (Low PI < 3.5, n=60) based on baseline preoperative PI values. Hemodynamic parameters and hypotensive episodes were observed every 3 minutes for 60 minutes post-block. Data was analyzed using SPSS version 26.0 Results: Group A showed a significantly higher incidence of hypotension compared to Group B [75.0% (n=45) vs. 35.0% (n=21); P < 0.001]. The baseline PI cutoff of 3.5 predicted spinal anesthesia-induced hypotension with a sensitivity of 68.2%, specificity of 72.2%, positive predictive value of 75.0%, negative predictive value of 65.0%, and a diagnostic accuracy of 70.0%. Considerably, 66% (n=43) of all hypotensive events occurred during the critical early window of first 20 minutes. Conclusion: A baseline preoperative perfusion Index more than or equal to 3.5 is a reliable, non-invasive, cost-effective predictor of early-onset spinal anesthesia-induced hypotension in obstetric patients, allowing a clinical shift from reactive treatment to proactive, individualized hemodynamic management