Preemptive Epidural Analgesia for Postoperative Pain Relief Revisited: Comparison of Combination of Buprenorphine and Neostigmine with Combination of Buprenorphine and Ketamine in Lower Abdominal Surgeries, A Double-blind Randomized Trial

CONTEXT: Postoperative pain relief provides subjective comfort to patient in addition to blunting of autonomic and somatic reflex responses to pain, subsequently enhancing restoration of function by allowing the patient to breathe, cough, and move easily. AIMS: The aim is to evaluate and compare the effects of neostigmine + buprenorphine and ketamine + buprenorphine for preemptive epidural analgesia for postoperative pain relief in patients undergoing abdominal surgeries under general anesthesia (GA). SETTINGS AND DESIGN: A double-blind randomized trial. SUBJECTS AND METHODS: A total of 60 American Society of Anesthesiologists physical status Classes I and II patients undergoing abdominal surgeries under GA were taken up for the study. They were randomly allocated into two groups, Group A and Group B of thirty patients each. Preemptive epidural analgesia for postoperative pain relief was provided by a combination of neostigmine 1 μg/kg + buprenorphine 2 μg/kg in Group A patients and ketamine 1 mg/kg + buprenorphine 2 μg/kg in Group B patients after induction of GA but before surgical incision. Postoperatively, vital parameters, pain score, requirement of top up doses, and side effects in the two groups were observed and recorded at 2, 4, 6, 10, 18, and 22 h. STATISTICAL ANALYSIS USED: Mean values within each of the Group A and Group B were compared using one-way analysis of variance (one-way ANOVA). Mean values between Group A and Group B were compared using double analysis of variance (two-way ANOVA). RESULTS: Group A patients had a significant analgesia (visual analog scale [VAS] pain scores reduced significantly from 54.6 ± 6.3 at 2 h to 8.1 ± 8.9 at 22 h postoperatively). Group B patients had significant analgesia too (VAS pain scores reduced significantly from 36 ± 12.5 at 2 h to 5.3 ± 10.9 at 22 h postoperatively). There was however no significant difference between the two groups with respect to the degree of postoperative analgesia on comparison of VAS scores, effect on vital parameters, and incidence of side effects. CONCLUSIONS: Either of the two combinations, neostigmine 1 μg/kg + buprenorphine μg/kg or ketamine 1 mg/kg + buprenorphine 2 μg/kg can be safely used for preemptive epidural analgesia for postoperative pain relief in patients undergoing abdominal surgeries under GA.