MINIMUM EFFECTIVE VOLUME OF BUPIVACAINE 0.25% + LIDNOCAINE 1% WITH EPINEPHRINE 5UG/ML REQUIRED FOR BRACHIAL PLEXUS BLOCK FOR UPPER LIMB SURGERIES.

Abstract

Supra-clavicular block (SCB) is a highly effective technique for providing analgesia for procedures performed distal to the mid-shaft of the humerus, offering rapid onset, superior quality of analgesia, and fewer complications compared to other regional anesthesia methods. Traditionally, large volumes of local anesthetics (LA) were administered using the peripheral nerve stimulator (PNS)-guided technique, but the introduction of ultrasound (US) guidance has enabled direct visualization of the spread of LA around the brachial plexus, allowing reduced volumes while maintaining block efficacy. Although several studies have reported lower volumes with US-guided SCB, some studies show no significant reduction in volume required for effective blockade in 95% of patients (ED95), with higher volumes sometimes needed. This study aimed to determine the minimum effective anesthetic volume (MEAV) for achieving surgical anesthesia in 95% of patients (MEAV95) using a combination of Lidocaine 1.0% with epinephrine 5 μg/mL and Bupivacaine 0.25% under US guidance. A cross-sectional study was conducted over five months at The Indus Hospital, including 74 patients undergoing elective upper limb surgeries. SCB was performed under US guidance with identification of the brachial plexus, subclavian artery, first rib, and pleura. The total LA volume was divided into three portions, deposited at 6, 3, and 12 o’clock positions around the brachial plexus. Initial LA volume of 30 ml was adjusted by 3 ml per patient according to the Dixon and Massey Up-and-Down Method. Sensory and motor blockade were assessed every five minutes up to 30 minutes. Among 74 patients (42 males, 32 females), a 59.5% success rate was observed. MEAV50 and MEAV95 were calculated as 4.99 ml (95% CI 3.3–6.6) and 21.15 ml (95% CI 12.86–97.1), respectively. Low volumes achieved effective blockade, supporting US-guided SCB efficiency, though multiple deposition sites and careful needle handling are necessary, and further randomized trials are recommended to validate ED95 estimations.