ABSTRACT
BACKGROUND: The addition of clonidine to local anesthetics for regional block has been shown to increase the duration of anesthesia and analgesia. This study was designed to determine whether the addition of clonidine to bupivacaine would produce an extension of the analgesic effect after intercostal nerve block (ICNB). METHODS: After informed consent, 30 ASA 1 or 2 patients undergoing appendectomy under general anesthesia were randomly divided into two groups. Before induction of anesthesia, ICNB using a posterior approach was performed with 15 ml of 0.25% bupivacaine plus epinephrine 1:200,000 with (Group BEC; n = 15) or without (Group BE; n = 15) clonidine 75 microgram. Analgesia was assessed by cold testing at 1/min intervals until cold sensation decreased. The duration of analgesia (time between injection and onset of pain) was recorded. We also recorded the visual analogue scale (VAS) of pain, the number of supplemental analgesics, heart rate and blood pressure, and side effects over 24 hours postoperatively. RESULTS: The onset time, duration of analgesia, number of analgesics, and heart rate and blood pressure were comparable in both groups. VAS scores were significantly lower in Group BEC than in Group BE at 12, 16, and 20 hours postoperatively. CONCLUSIONS: The addition of clonidine to bupivacaine with epinephrine may be a useful adjunct and can prolong the duration of analgesia after ICNB without significant side effects.