Predictive Value of Pulse Oximetry – Derived Perfusion Index for Hypotension After Spinal Anesthesia for Elective Caesarean Deliveries: A Prospective Study

Introduction: The study aims to determine if baseline perfusion index can be used to predict hypotension following spinal anesthesia in elective lower segment caesarean delivery (LSCS) and to find the correlation between baseline perfusion index and incidence of hypotension following spinal anesthesia in parturients undergoing LSCS.
Material and Methods: A prospective, single-center observational study was conducted on parturients aged 20 to 35 years scheduled for elective LSCS, recruited based on specific inclusion and exclusion criteria. 
Results: The mean age of the participants was 31.15 ± 2.70 years, with a mean baseline perfusion index (PI) of 3.45. The majority (62.5%) achieved a sensory blockade level of T6 five minutes after spinal anesthesia. Approximately 68.8% experienced hypotension. A baseline PI of ≥3.5 was significantly associated with increased incidence of hypotension (p = 0.004), and the PI showed moderate sensitivity (57.58%) and high specificity (86.67%) for predicting hypotension. ROC analysis showed an AUC of 0.775 (p = 0.002), and a moderate positive correlation (r = 0.484, p < 0.001) was observed between baseline PI and the number of doses of vasopressor administered.
Conclusion: Baseline perfusion index (PI) at a cutoff value of 3.5 can be reliably used as a valuable predictor of hypotension in parturients undergoing caesarean delivery under spinal anesthesia, with a positive predictive value of 91 % and diagnostic accuracy of 67 %.