Perfusion Index as a Predictor of Spinal Anesthesia Success: A Time-dependent Receiver Operating Characteristic Curve Analysis
A. Vijeth Kishan, Pabitra Ghoshal, Viraj Namshikar, Abhinandan Annasab Chougale, Sheetal Sagar Janaj, Himanshi YadavAbstract
Background:
Traditional assessments of spinal anesthesia success, such as pinprick and temperature tests, are subjective and rely on patient cooperation, limiting their utility in sedated, pediatric, or uncooperative patients. Perfusion index (PI), a noninvasive parameter from pulse oximetry reflecting peripheral perfusion via the pulsatile-to-nonpulsatile blood flow ratio, may objectively indicate sympathetic blockade-induced vasodilation.
Methods:
In this prospective analytical study, 229 American Society of Anesthesiologists I–II patients aged 18–50 years undergoing elective surgeries under spinal anesthesia had PI, PI ratio (post-/preblock), mean arterial pressure (MAP), heart rate, and skin temperature measured at baseline and 2, 4, 6, 10, 15, and 30 min postblock. Block success was defined as bilateral pinprick sensory loss to T10 within 30 min. Time-dependent receiver operating characteristic curves were used to assess predictive accuracy.
Results:
Spinal anesthesia succeeded in 219/229 patients (95.6%). PI rose significantly from baseline (0.95 ± 0.31) to 30 min (9.46 ± 1.85;
Conclusion:
PI and PI ratio provide early, objective prediction of spinal block success, outperforming subjective tests in challenging cases. Clinical adoption could streamline assessment.