Perfusion Index for Assessing Femoral and Sciatic Nerve Block Success in Lower Extremity Surgery

Peripheral nerve blocks are increasingly used in lower extremity surgery as an alternative to general anesthesia. However, traditional methods used to assess block success, such as sensory and motor testing, are subjective, time-consuming, and dependent on patient cooperation. The perfusion index (PI), measured non-invasively using pulse oximetry, reflects peripheral perfusion changes associated with sympathetic blockade and may serve as an early indicator of block effectiveness. This study aims to evaluate whether PI can be used as an early and reliable marker for assessing the success of combined femoral and sciatic nerve block in patients undergoing elective lower extremity surgery. A total of 80 patients aged 18-65 years with ASA physical status I-III will receive ultrasound- and nerve stimulator-guided combined femoral and sciatic nerve block. Hemodynamic parameters and perfusion-related variables, including PI, capillary refill time, and skin temperature, will be recorded at baseline and at 5, 10, 20, and 30 minutes after block administration. The results will be compared with traditional sensory and motor block assessments to determine whether PI provides an earlier and objective assessment of block success.