The Ability of Perfusion Index and Positional Perfusion Index Variation to Predict Spinal Anesthesia-Induced Hypotension in Elderly Patients: A Prospective Observational Study

Background: Spinal anesthesia (SA) is a popular anesthetic technique for several surgeries; however, it is mostly associated with hypotension. The perfusion index (PI) can predict hypotension after spinal and general anesthesia. We aimed to evaluate the predictability of PI postural change, supine and sitting PI to post-SA hypotension in elderly patients.Methods: This study was conducted on 68 elderly patients aged >65 years, scheduled for elective orthopedic surgical operations under SA in supine position. PI, arterial oxygen saturation, blood pressure, and heart rate were initially recorded at sitting and supine positions then 5, 10, and 20 minutes after subarachnoid drug injection (in supine position). ΔPI=PI supine−PI sitting. The relative change in PI (rPI) =ΔPI/PI sitting× 100.Results: Hypotension occurred in 33.82% of patients. The Δ PI was 0.53±0.24, and the r PI was 14.18±6.41%. Δ PI at cut-off >0.6 and r PI at cut-off > 14%; could predict SA-induced hypotension with a sensitivity of 82.61 and 86.96%, respectively, and specificity of 88.89 and 77.78%, respectively. There was an insignificant difference between Δ PI and r PI and between r PI and baseline supine in predicting SA-induced severe hypotension. The prediction of SA-induced hypotension was higher with Δ PI than baseline sitting and baseline supine (P=0.002 and 0.027) and between r PI and baseline sitting (P=0.047).Conclusions: In elderly patients, the Δ PI has a higher predictive value for SA-induced hypotension than baseline sitting and baseline supine with comparable prediction ability between Δ PI and r PI.