Correlation of Skin Temperature Variation, Cold Test, and Pinprick Test with Sensory Block Height Following Spinal Anesthesia

Abstract

Introduction: Accurate evaluation of sensory block height after spinal anesthesia is essential for safe and effective anesthesia. Conventional cold and pinprick tests are subjective, prompting interest in skin temperature changes as an objective indicator of sympathetic blockade.

Materials and Methods: This prospective observational study enrolled 35 ASA II patients undergoing cesarean section under spinal anesthesia. Hyperbaric bupivacaine 0.5% (10 mg) with fentanyl 25 µg was administered intrathecally. Skin temperature was measured at dermatomes T4, T6, and T8 before anesthesia and at 1–5 minutes afterward. Sensory block was assessed using cold and pinprick tests. Diagnostic accuracy of temperature changes was evaluated using ROC analysis.

Results: Skin temperature increased significantly over time at all dermatomes (p < 0.05), with the greatest rise at T8, followed by T6 and T4. Cold and pinprick tests showed time-dependent associations with block height, becoming uniformly positive by minute four. Skin temperature changes demonstrated excellent diagnostic performance for predicting positive cold (AUC = 0.943) and pinprick test results (AUC = 0.944). Temperature increases of 0.35–0.45 °C yielded high sensitivity and specificity.

Conclusion: Skin temperature monitoring is a rapid, objective, and reliable method for assessing sensory block height following spinal anesthesia.