Role of Pleth variability index and perfusion index for predicting hypotension following spinal anaesthesia in patients undergoing caesarean section

Abstract

Pleth variability index and perfusion index are noninvasive continuous hemodynamic monitors that can assess peripheral vascular tone and intravascular volume status and thus can predict hypotension following spinal anaesthesia. Spinal anaesthesia is the choice of anaesthesia in caesarean sections. Approximately 70% of patients will develop hypotension after spinal anaesthesia, which can lead to maternal and fetal complications. Thus, the Pleth Variability Index (PVI) and perfusion index (PI) allow the identification of patients with an increased susceptibility to hypotension following spinal anaesthesia.: This prospective observational study was conducted in a tertiary care centre with 102 obstetric patients undergoing spinal anaesthesia for caesarean section in the age group of 18-35 years who were full term with ASA≤ grade II, BMI 35kg/m. Pleth variability index and Perfusion index were measured before and after spinal anaesthesia. The data was analysed using ROC and multiple linear regression models using SPSS software. In the hypotension group PVI and PI at one minute is higher than without the hypotension group. PVI at one minute is an independent factor for predicting hypotension following spinal anaesthesia (P=0.039). ROC analysis of baseline and one-minute PVI showed only one-minute PVI can predict hypotension with an AUC-0.633(95% CI-0.492-0.774) and an optimal cut-off value of 19.5. ROC analysis of baseline and one-minute PI revealed both baseline and one-minute PI could predict hypotension with AUC-0.507 (95% CI 0.378-0.636) and 0.540 (95% CI 0.410-0.682) respectively. The optimal cut-off of baseline PI for predicting hypotension is 2.5 with a sensitivity of 51.4%, specificity of 61.5% and one-minute PI is 4.5 with a sensitivity of 60.8% and specificity of 53.8%. Baseline PVI is not a predictor of hypotension and one-minute PVI ≥19.5 can predict hypotension following spinal anaesthesia. One minute PI ≥ 4.5 is more sensitive in predicting hypotension than Baseline PI ≥2.5.: The Pleth Variability Index and Perfusion Index are noninvasive monitors which can predict hypotension following spinal anaesthesia in cesarean sections.