Perfusion index as predictor of intraoperative hypotension following subarachnoid block in cesarean section: A prospective, observational study

Background: Perfusion index (PI) can be used to assess peripheral perfusion dynamics as it depicts the changes in peripheral vascular tone. Increased risk of fall in blood pressure following subarachnoid block (SAB) has been reported in pregnant patients with raised PI value due to their decreased peripheral vascular resistance. This study aimed to evaluate PI as a noninvasive tool for predicting incidence and severity of maternal hypotension following SAB in parturients undergoing lower segment cesarean section (LSCS). Materials and Methods: A prospective, observational study was conducted on 120 American Society of Anesthesiologists-II parturients undergoing LSCS under SAB. Noninvasive blood pressure, heart rate (HR), and PI were recorded at baseline and at 1-min interval till delivery of baby. Episodes of hypotension, bradycardia, total amount of vasopressor consumption, intraoperative nausea, vomiting (IONV), and APGAR scores were observed. Results: Receiver operator characteristics curve determined the optimal cutoff point for PI to predict intraoperative hypotension and IONV was 3.82 with a sensitivity of 79.07% and specificity of 72.73%. Incidence of hypotension in subjects with a higher baseline PI (≥3.82) was 79.1% compared with 20.9% with low baseline PI (<3.82). Amount of vasopressor used and incidence of IONV was significantly higher in subjects with high baseline PI (P < 0.001). Conclusions: There is a significant correlation between PI and SAB-induced hypotension in parturients undergoing LSCS. Pregnant patients with higher baseline PI (>3.82) are at a greater risk of developing hypotension.