Perfusion Index after Supraclavicular Brachial Plexus Block as an Early Predictor of Successful Block

Abstract

Objective: Supraclavicular brachial plexus block is a highly popular upper extremity anesthetic technique. Theoretically, after local anesthetic agent is injected, temporary vasodilatation, sensory loss and motor weakness ensue. The assessment of successful block relies on subjective data of sensory block and patient co-operation. The present study hypothesized that perfusion index (PI) is an early predictor and provide a cut-off value for the successful block. Materials and Methods: Sixty-two patients undergoing upper extremity operation under ultrasound-guided supraclavicular brachial plexus block were included. PI values were assessed on the operated limb at baseline, 0, 1, 3, 5, and 10 minutes after block. The patients were divided into three groups. Upon incision, patients that reported pain but tolerated the operation after anesthetic supplement were in the supplement group, patients that reported persistent pain after anesthetic supplement were in the failed group, and patients that did not required any supplement were in the complete group. The three groups were monitored with PI values. Results: The supraclavicular brachial plexus block of fifty-nine patients (95.16%) were successfully blocked, which 42 patients (67.74%) had complete block and 17 patients (27.42%) needed supplemental treatment. Three patients (4.84%) had failed block and were converted to general anesthesia. The PI value was continuously rising from baseline in successfully blocked patients. PI value at three minutes after local anesthetic injection showed block success at cut-off value of 3.6, respectively. Conclusion: Successful block could be determined early by the increase of PI value from baseline. A PI value of more than 3.6 at 3-minute after block is a good early predictor of successful block. © 2022 JOURNAL OF THE MEDICAL ASSOCIATION OF THAILAND.