Preemptive caudal epidural analgesia in adult patients undergoing lumbar disc surgery: a comparison between neostigmine, ropivacaine and their mixture

This prospective, randomized double blind study was designed to evaluate the analgesic characters and profile of ropivacaine/ neostigmine mixture in comparison with the analgesic characters of ropivacaine and neostigmine when used alone and injected caudally in cases subjected for elective lumbar disc surgery at Mansoura University Hospitals. Thirty adult patients ASA I-II subjected for elective lumbar disc surgery at Mansoura University Hospital were enrolled in this study. General anesthesia was induced with 5 mg /kg thiopental sodium and tracheal intubation was facilitated using atracurium 0.5 mg/kg. Patients were randomly assigned into three equal groups [n= 10] according to the regimen of caudal drug injection. The injectate was prepared by an anesthesiologist not involved in the evaluation of the patients. Patient's groups were as follows: Ropivacaine group [R], received ropivacaine 0.2% in saline with total volume 30 ml. Neostgmine group [N], received neostgmine 4 ug /kg in total volume 30 ml. Ropivacaine-Neostgmine group [RN], patients received ropivacaine 0.2% + neostigmine 4 ug/kg in total volume 30 ml . Intraoperative monitoring for ECG, heart rate,mean arterial blood pressure, arterial oxygen saturation and capnography was recorded every 15 minutes till the end of the study period. Postoperative pain was assessed immediately after surgery and at 2, 4, 8, 12 hour postoperatively by the visual analogue scale [VAS], where 0 =no pain, 5= medium degree of pain and 10 =severe pain. The time at which first analgesic medications [mepredine, 25mg dosage] required by the patient in the postoperative period was recorded .Duration of postoperative analgesia [duration from the end of surgery to the first pain sensation] was recorded. Postoperative complications [nausea, vomiting, and any other complications] were recorded. There were no statistically significant differences between the three groups as regard hemodynamics, nausea and vomiting while urine retention was more observed in all patients received ropivacaine [R and RN groups]. As regard postoperative analgesia, group RN [received ropivacaine+ neostigmine] had the best pain score and longer duration of postoperative analgesia as compared with the other groups. Addition of neostigmine 4 micro g/kg to caudal ropivacaine 0.2% improves the quality of postoperative analgesia and prolongs its duration compared with caudal ropivacaine or neostigmine alone without increasing incidence of side effects in patients subjected for lumbar disc surgery