Ultra-low Dose Naloxone Added to 0.5% Bupivacaine Significantly Prolongs the Duration of Analgesia Following Supraclavicular Brachial Plexus Block

Abstract

In this prospective, randomized, double-blind study, we evaluated the effect of ultra-low dose of naloxone on duration of supraclavicular brachial plexus block. It was hypothesized that naloxone can prolong the duration of sensory block. Following approval by Hospital Ethical Issues Committee, eighty patients scheduled for upper limb surgery under supraclavicular brachial plexus block were randomly allocated into control group who received 20ml bupivacaine with 3 ml normal saline (Group B) or study group that received 20ml bupivacaine with 100 mcg. of naloxone in 3 ml saline, (Group BN). Onsets of sensory and motor blockade were assessed at an interval of 3 min following the block. Duration of sensory and motor block was considered to be the time interval between the complete block and the first post operative pain reported by patient and complete recovery of motor functions respectively. The difference in onset time for sensory and motor block was statistically significant between two groups but clinically it may be considered insignificant. The recovery of sensory block was slower in group BN (15.6 ± 3.2 hr) compared to group B (13.3 ± 2.4 hr) [p=0.0001]. The recovery of motor block was slower in group B (13.3 ± 2.5 hr) compared to group BN (11.6 ± 4.3) [P=0.03]. In conclusion, addition of ultra-low dose of naloxone to bupivacaine in supraclavicular block prolongs the duration of sensory block and reduces duration of motor block significantly as compared to bupivacaine alone.