Efficacy of inhalation of a nitrous oxide and oxygen mixture for pain management during rigid cystoscopy: a randomized controlled trial


  • Tanawat Lohityothin Division of Urology, Department of Surgery, Faculty of Medicine, Thammasat University, Pathumthani, Thailand
  • Valeerat Swatesutipan Division of Urology, Department of Surgery, Thammasat University Hospital, Thammasat University, Pathumthani, Thailand




Entonox, nitrous oxide, cystoscopy, pain


Objective: To evaluate the efficacy of pain management using inhalation of a nitrous oxide and oxygen mixture during rigid cystoscopy.

Materials and Methods: A total of 55 patients were prospectively selected and randomized to receive oxygen (27) or Entonox (28). Both groups were given the respective gas for 3 minutes via breath-activated facemask before cystoscopy and continued to breathe the gas until the end of the procedure. The oxygen and Entonox groups received 20 ml 2% lidocaine gel intraurethral 15 minutes before the procedure. Heart rate, and numeric pain rating scales were recorded before, during, and after the cystoscopy.

Results: Fifty-five patients were randomized into two groups, 27 were given oxygen and 28 Entonox. There were no statistically significant differences between the groups in terms of baseline patient characteristics. Intraoperative rigid cystoscopy pain scores were significantly lower in the Entonox group than in the oxygen group (2.4 vs 4.2, p = 0.009). There were no significant differences between the two groups as regards postoperative pain, intraoperative and post-operative heart rates, and side effects.

Conclusion: Entonox significantly reduces intraoperative cystoscopy-related pain, without significant complications.


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How to Cite

Lohityothin, T., & Swatesutipan, V. (2023). Efficacy of inhalation of a nitrous oxide and oxygen mixture for pain management during rigid cystoscopy: a randomized controlled trial. Insight Urology, 44(2), 62–7. https://doi.org/10.52786/isu.a.73



Original article