Supraclavicular Brachial Plexus Block by Nerve Stimulator or Ultrasound: An Observational Cross-sectional Study

Abstract

Introduction: Supraclavicular approach to the brachial plexus block is considered to be one of the most effective anaesthetic procedures for upper limb surgeries. Peripheral Nerve Stimulation (PNS) has traditionally been used as the gold standard technique for nerve location. More recently, Ultrasound (USG)-guided single injection supraclavicular block is used which allows direct visualisation of nerve, but its use is limited by cost constraints and the level of expertise needed. Aim: To compare the efficacy of USG and PNS in supraclavicular brachial plexus block especially the onset of motor block in orthopaedic forearm surgeries. Materials and Methods: An observational cross-sectional analytical study was conducted from January 2019 to January 2020 on 60 patients attending emergency operation theatre for orthopaedic forearm surgeries. They were allocated alternatively to one of the two groups (30 in each group) based on the technique of nerve block, either using USG or PNS. Block execution time (puncture time), the number of needle passes, time of onset of sensory block, time of onset of motor block, quality of sensory block, quality of motor block, the intraoperative requirement of opioids, complications, success, and failure were the exposure variables. The qualitative data were compared using Chi-square test and for comparison of the continuous variable, the student’s t-test and Fisher’s exact test were used. The p-value<0.05 was considered statistically significant. Results: Patients in both groups were comparable concerning demographic parameters like age, sex, and American Society of Anaesthesiologists (ASA) physical status. The mean time of onset of a motor block using the USG-guided technique was 8.6±1.0 minutes, and using a PNS was 11.1±1.0 minutes (p-value<0.01). There was a 93.3% success rate in the USG- guided technique, compared to an 83.3% success rate in the PNS method (p-value of 0.222). No complications were seen in the USG-guided group. In the PNS-guided group, four complications were noted among 30 patients, the most common being vascular puncture (2 cases). Conclusion: USG-guided supraclavicular block was superior to PNS technique in terms of rapid onset motor and sensory block, block quality, improved success rate, and fewer complications.