Perfusion Index and Spinal Hypotension in Day-Case Knee Arthroscopy

This prospective observational study aims to investigate the role of the baseline perfusion index (PI) in predicting spinal anesthesia-induced hypotension (SAIH) in ASA I-II patients undergoing day-case knee arthroscopy. Spinal anesthesia is a widely preferred technique for lower extremity surgeries, including knee arthroscopy. However, sympathetic blockade during spinal anesthesia frequently leads to significant hemodynamic instability, particularly hypotension, which can result in adverse perioperative outcomes. While age and baseline blood pressure are traditional risk factors, they often fail to accurately predict the onset of hypotension in healthy populations. The perfusion index (PI), a non-invasive parameter measured via pulse oximetry, reflects peripheral vascular tone and baseline sympathetic activity. An elevated baseline PI indicates baseline vasodilation and a higher suscep