Effect of addition of fentanyl to local anesthetic in brachial plexus block on duration of analgesia

INTRODUCTION/CONTEXT: A comparative study was carried out to evaluate the analgesic efficacy and side effects of addition of fentanyl to local anesthetic undergoing surgeries on forearm and elbow. All patients were hemodynamically stable, and there were no serious side effects in any of the patients in both the groups. The difference in the mean duration of analgesia between the groups was statistically significant (P<0.01). So we can conclude- Addition of Fentanyl to local anaesthetic in brachial plexus block increases duration of analgesia. MATERIALS AND METHODS: Patients were randomly divided into two groups: group I (control) and group II (study). All the patients were subjected to brachial plexus block with supraclavicular approach. After obtaining paraesthesia, drugs were administered as follows: Group I (control): bupivacaine 0.5% 20 mL + lignocaine 2% 10 mL + NS 1 mL Group II (study): bupivacaine 0.5% 20 mL + lignocaine 2% 10 mL + fentanyl 1 mL (50 microgm). Observations were noted. All the relevant information was recorded on a pretested, predefined, semi-open pro forma sheet. Regular monitoring of PR, BP and RR, side effects,degree of sedation were recorded. Evaluation of pain and pain relief was done according to McGill pain questionnaire (0- no pain to 5- excruciating pain). When patients complained of discomforting pain (McGill grade II), parenteral analgesic was prescribed, and the total number of doses in the 24-hour period was noted. RESULTS: The duration of analgesia in group II (study) was significantly longer (695±85 min) than those in group I (415±78 min). However, onset time of analgesia was prolonged in group 2. We conclude that the addition of fentanyl to local anesthetics causes an improved success rate of sensory blockade but a delayed onset of analgesia, although this may be accounted for by the decreased pH caused by fentanyl. There was no statistically significant difference in the incidence of side effects between the two groups. CONCLUSIONS: This study has shown that the mean duration of analgesia is extended if fentanyl is added to local anesthetics, without increasing the side effects.