RESUMEN
We designed this study to evaluate the postoperative analgesic efficacy and safety of intrathecal [IT] neostigmine, intrathecal [IT] morphine, and their combination in patients undergoing herniorrhaphy under spinal anesthesia. Eighty adult patients were randomly divided into four groups to receive isotonic sodium chloride solution 0.5 ml, neostigmine 100ug, morphine 0.3 mg or the combination of IT neostigmine 50 ug and morphine 0.15 mg with IT 0.5 0/0 hyperbaric bupivacaine 15 mg. There were no significant differences among the four groups with regard to spinal anesthesia, age, heart rate, or mean arterial blood pressure. Postoperative analegisa was provided by IM diclofenac. Compared with the saline group, the time to first use of analgesic was significantly longer in neostigmine group [p= 0.02], with lower 24 h analgesic consumption [p=0.001]. Nausea and vomiting were the most common side effects of IT neostigmine 60 0/0. Analgesic effectiveness was similar between the neostigmine and morphine groups. Compared with the neostigmine group, the combination group had significantly longer analgesic effects [P=0.02] with less incidence of nausea and vomiting [p=0.04]. Compared with the morphine group, the combination group tended to have prolonged times to first use of analgesic [p=0.02] with lower incidence of pruritus [p=0.03]. the combination of IT neostigmine 50 ug and IT morphine 0.15 mg produce longer postoperative analgesia with fewer side effects than IT neostigmine 100ug or IT morphine 0.3 mg alone. Intrathecal [IT] neostigmine 100ug produced postoperative analgesia for herniorraphy similar to [IT] morphine 0.3mg, but with high incidence of nausea and vomiting, morphine group had high incidence of pruritus. Thus, combination of both has higher analgesic effects with lower side effects than single drug alone