Comparison of intravenous tramadol and ketamine for prevention of catheter-related bladder discomfort after laparoscopic surgery: a randomized, placebo-controlled, double-blind study

Background: Catheter-related bladder discomfort (CRBD) is a distressing symptom after anesthesia. Objectives: To compare the efficacy of tramadol and ketamine to prevent CRBD after laparoscopic surgery. Methods: After registration with the Thai Clinical Trial Registry (TCTR20140220001), we conducted a randomized controlled trial in 210 patients aged 18-70 years with American Society of Anesthesiologists physical status I or II undergoing elective laparoscopic surgery requiring bladder catheterization. These patients were randomly allocated into 1 of 3 groups: Group T received intravenous (i.v.) tramadol 1.5 mg/kg, Group K received i.v. ketamine 0.5 mg/kg, and Group P received i.v. saline as a placebo before catheterization. Patients received i.v. morphine for postoperative pain control. An anesthesiologist blinded to the randomization evaluated postoperative and CRBD pain severity using visual analog scales (VAS). The cumulative postoperative and CRBD pain was calculated by multiplying mean VAS scores by the hours of assessment. Results: Groups T and K had significantly less cumulative CRBD pain compared with placebo (P = 0.04 and 0.001, respectively). Cumulative postoperative pain, total 24-h morphine consumption, and adverse effects were comparable between groups. Group T had a significantly lower incidence of shoulder pain (7/67, 10%) than Group K (21/70, 30%), and Group P (24/70, 34%) 24 h after surgery (P = 0.006 and 0.001, respectively). Conclusions: Tramadol 1.5 mg/kg and ketamine 0.5 mg/kg administered i.v. before bladder catheterization are both effective in reducing the 24-h cumulative postoperative CRBD after laparoscopic surgery without significant adverse effects. Tramadol also decreases the incidence of postlaparoscopy shoulder pain.