Dorsal penile nerve block with ropivacaine versus intravenous tramadol for the prevention of catheter-related bladder discomfort: study protocol for a randomized controlled trial

Background: Catheter-related bladder discomfort (CRBD) is common in male patients under general anesthesia, and it may cause patient agitation and exacerbated postoperative pain. In this study, we will enroll male patients undergoing elective surgery with urinary catheterization after anesthetic induction and compare the efficacy of a dorsal penile nerve block (DPNB) and intravenous tramadol for the prevention of CRBD. Methods/Design: This trial is a prospective, open-label, randomized controlled trial that will test the superiority of a dorsal penile nerve block with 0.33 % ropivacaine to the use of intravenous tramadol 1.5 mg/kg for CRBD prevention. A total of 60 male patients undergoing elective surgery with urinary catheterization after anesthetic induction will be randomized to receive either DPNB with 0.33 % ropivacaine (DPNB group) or intravenous tramadol 1.5 mg/kg (TRAM group) after the completion of surgery but before extubation. The primary outcome is the incidence and severity of CRBD. Secondary outcomes include Visual Analog Score (VAS) for postoperative pain, number of patients requiring sulfentanil after operation, acceptance of an indwelling urinary catheter after extraction of the catheter, and postoperative side effects, which include postoperative nausea/vomiting (PONV), vertigo, sedation, drowsiness, and dry mouth. Discussion: For CRBD prevention, this trial is planned to test the superiority of a dorsal penile nerve block with 0.33 % ropivacaine to the use of intravenous tramadol 1.5 mg/kg. The results will provide new insight into the mechanism of CRBD and new clinical practice for the prevention of CRBD.