Comparative evaluation of addition of either fentanyl or clonidine to bupivacaine in spinal anesthesia – a randomized controlled trial
Abstract
Background: Single dose subarachnoid anesthesia is a commonly used anesthetic technique for pelvic and lower limb surgeries. Various adjuvants, e.g. opioids, alpha 2 agonists, neostigmine, midazolam etc. have been used to counter some of the shortcomings of the technique. Synthetic lipid soluble opioids like fentanyl for hemodynamic stability or clonidine for prolongation of duration have been used. We wanted to compare both the drugs with a control when used in conjunction with local anesthetics in lower abdominal and pelvic surgeries with regard to sensory and motor block with early postoperative analgesia along with their side effect profile.
Methodology: One hundred and fifty adult patients of ASA status I and II, posted for lower abdominal and pelvic surgeries, were randomly divided into three groups. Group BC (bupivacaine + clonidine) received 50 µg clonidine while BF (bupivacaine + fentanyl) received 50 µg of fentanyl, the third group received equal volumes of normal saline (Group NS, bupivacaine + normal saline) for subarachnoid block. The duration of anesthesia, analgesia, motor blockade and side effects like sedation, bradycardia and hypotension were noted and subjected to statistical analyses with ANOVA (analysis of variance) and Kruskal-Wallis test as and when appropriate.
Results: All of the 150 patients completed the study. The duration of surgical anesthesia was not significantly higher in the experimental groups. But the duration of analgesia was higher in BC than BF which in turn was higher than the Group NS [281.26 ± 97.57, 237.80 ± 58.49 min and 190.48 ± 61.94 min respectively]. The sedation and the intraoperative motor blockade were similar, in Group BC, L1 regression time was 232.76 ± 94 min which was higher compared to Group BF (202.34 ± 60 min) and Group BN (172.28 ± 56 min) but statistically insignificant. The hemodynamic instability with regard to hypotension was more in Group BC than BF.
Conclusion: Addition of 50 µg of clonidine to intrathecal bupivacaine produces prolonged duration of analgesia in surgical anesthesia. The onset of hemodynamic imbalance was from forty minutes in Group BC which prompts for an additional monitoring in those cases. There is no excess sedation with the above said dose of clonidine.
