Self-adjusted Nitrous Oxide During Urodynamic Studies Reduces Patient Pain Without Compromising Study Quality: A Randomized Controlled Trial

Abstract

Background and objectiveA urodynamic study (UDS) is a routine clinic procedure that can cause significant discomfort for certain patients, with no satisfactory analgesic alternatives currently available. Our aim was to evaluate the effectiveness of low-dose self-adjusted nitrous oxide (SANO), titrated to the patient’s desired effect, on standard metrics for bladder function and on patient-reported pain and anxiety. MethodsWe conducted a single-institution, double-blind, randomized crossover trial in adults undergoing UDS. Each patient underwent two consecutive UDS runs, randomized to receive oxygen during the first run followed by SANO during the second run, or vice versa. UDS outcomes (capacity, detrusor strength, residual volume) and patient subjective outcomes (Visual Analog Scale for pain and anxiety, operator assessment of verbal feedback) were compared between the two runs. Secondary analyses were performed to compare outcomes during the first UDS run and adjust for treatment order. A paired Wilcoxon signed rank-sum test and McNemar’s χ2 test were used to compare continuous and categorical variables, respectively. Adverse events were recorded. Key findings and limitationsNineteen patients were randomized (10 to oxygen for the first run, 9 to SANO for the first run). UDS outcomes did not differ between the two arms. Patients reported significantly less pain during the SANO run than during the oxygen run (p = 0.046). Verbal feedback was significantly better with SANO (p = 0.001). Most patients (15/19, 79%) stated that they would prefer to receive SANO during future UDS. There were no significant complications. Conclusions and clinical implicationsSANO oxide is a safe and effective means of preserving standard adult UDS metrics while significantly reducing patient-reported pain. Patient summaryUrodynamic tests (UDS) for evaluation of lower urinary tract symptoms can cause discomfort and pain. Our study shows that nitrous oxide gas self-adjusted by patients had no effect on UDS test outcomes or on verbal feedback during the procedure, and reduced discomfort and pain in comparison to oxygen. Nitrous oxide may an attractive option for patients who are reluctant to undergo UDS.