Magnesium and Bladder Discomfort after Transurethral Resection of Bladder Tumor

Abstract

BACKGROUND Catheter-related bladder discomfort occurs because of involuntary contractions of the bladder smooth muscle after urinary catheterization. Magnesium is associated with smooth muscle relaxation. This study hypothesized that among patients having transurethral resection of bladder tumor, magnesium will reduce the incidence of postoperative moderate-to-severe catheter-related bladder discomfort. METHODS In this double-blind, randomized study, patients were randomly allocated to the magnesium group (n = 60) or the control group (n = 60). In magnesium group, a 50 mg/kg loading dose of intravenous magnesium sulfate was administered for 15 min, followed by an intravenous infusion of 15 mg · kg-1 · h-1 during the intraoperative period. Patients in the control group similarly received normal saline. The primary outcome was the incidence of catheter-related bladder discomfort above a moderate grade at 0 h postoperatively. None, mild, moderate, and severe catheter-related bladder discomfort at 1, 2, and 6 h postoperatively, patient satisfaction, and magnesium-related adverse effects were also assessed. RESULTS The incidence of catheter-related bladder discomfort above a moderate grade at 0 h postoperatively was significantly lower in the magnesium group than in the control group (13 [22%] vs. 46 [77%]; P < 0.001; relative risk = 0.283; 95% CI, 0.171 to 0.467; absolute risk reduction = 0.55; number needed to treat = 2); similar results were observed for catheter-related bladder discomfort above a moderate grade at 1 and 2 h postoperatively (5 [8%] vs. 17 [28%]; P = 0.005; relative risk = 0.294; 95% CI, 0.116 to 0.746; and 1 [2%] vs. 14 [23%]; P < 0.001; relative risk = 0.071; 95% CI, 0.010 to 0.526, respectively). Patient satisfaction on a scale from 1 to 7 was significantly higher in the magnesium group than in the control group (5.1 ± 0.8 vs. 3.5 ± 1.0; P < 0.001; 95% CI, 1.281 to 1.919). Magnesium-related adverse effects were not significantly different between groups. CONCLUSIONS Magnesium reduced the incidence of catheter-related bladder discomfort above a moderate grade and increased patient satisfaction among patients having transurethral resection of bladder tumor. EDITOR’S PERSPECTIVE