• J G Calleary, J Masood, R Van-Mallaerts, and J M Barua.
• Department of Urology, Directorate of Special Surgery, Harold Wood Hospital, Essex, United Kingdom. johngcall@aol.com
• J. Urol. 2007 Jul 1;178(1):184-8; discussion 188.

PurposeFlexible cystoscopy in men younger than 55 years is painful despite the current best standard anesthesia (20 ml 2% lidocaine gel 15 minutes before endoscopy). The anesthetic value of lidocaine gel is debated and led us to seek an alternative. Nitrous oxide is a well established analgesic and anxiolytic agent, and it significantly reduces pain associated with transrectal ultrasound guided prostate biopsy. We studied its use in flexible cystoscopy in men younger than 55 years.Materials And MethodsA total of 61 patients were prospectively randomized to receive air (31) or Entonox (30). Both groups had 3 minutes of gas via a breath activated facemask (either Entonox or air) before endoscopy. The gel control group was comprised of 8 patients who underwent cystoscopy after instillation of lidocaine gel. The air and Entonox groups had lidocaine gel as per best standard. Vital signs were recorded before, during and after cystoscopy. Patients completed a visual analog score for gel insertion and cystoscopy.ResultsThere were no statistically significant differences between the groups in terms of baseline characteristics. Pain scores for cystoscopy (p<0.001) and intraoperative pulse rate (p=0.008) were significantly less with Entonox. Side effects were transient and seen more often with Entonox (p<0.05). More of the air group would require more analgesia (p=0.001) or a general anesthetic (p=0.011) if undergoing repeat cystoscopy.ConclusionsNitrous oxide inhalation significantly reduces cystoscopy related pain without significant complications. We propose that Entonox should be the anesthetic agent of choice for men younger than 55 years.

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