Comparison of Mepivacaine and Bupivacaine as an Adjuvant of Morphine for Benign Anorectal Surgery under Caudal Anesthesia

ABSTRACT

BACKGROUND/AIMS: The caudal anesthsia is most commonly used for benign anorectal surgery, The combination of long-acting anesthetics and opiates has been used for longer duration and successful control of postoperative pain. But the side effects of peridural anesthesics and morphine have commonly occured in caudal anesthesia. This study was performed to assess the difference in clinical effects between peridural mepivacaine and bupivacaine with morphine. METHODS: We evaluated the clinical effects in 60 patients who had anal operation with Jack-Knife position under caudal anesthesia. We divided randomly these 60 patients into two groups, M and B groups (in each group, 30 patients included). Group M (n=30) was given 2% mepivacaine 20 ml with morphine 2 mg caudally, and Group B (n=30) was given 0.5% bupivacaine 20 ml with morphine 2 mg in the same manner. We measured the onset time, duration, postoperative analgesia, and side effects including urinary retention. RESULTS: The onset time for analgesia was significantly shorter in group M than in group B. The duration of postoperative pain complaints was significantly longer in group M than in group B. The postoperative analgesic effects and side effects were not significantly different between two groups. CONCLUSIONS: Caudal mepivacaine and morphine mixture is effective for control of postoperative pain without significant side effects.