Transrectal Prostate Biopsy: Nitrous oxide may significantly reduce patient-rated pain

The researchers revealed that patient-adjusted N2O did not reduce anxiety associated with a transrectal prostate biopsy but significantly reduced pain as compared to standard anaesthesia.

The primary endpoint, scores on a standardized anxiety questionnaire, did not vary significantly between patients randomized to N2O or standard care. However, patients in the N2O group reported significantly less pain, and urologists who performed the biopsies rated patient tolerance of the procedure significantly better with N2O addition.

"Procedure time and complication rates did not differ between the two groups," the researchers reported.

According to the authors, this is the first prospective, randomized, controlled study evaluating the effects of low-dose (20%-45%) N2O on patient experience during transrectal prostate biopsy.

"There was not an observed reduction in the study’s primary endpoints related to patient anxiety; however, there was an observed reduction in secondary endpoints of patient-perceived pain," the researchers wrote. "Overall, self-adjusted nitrous oxide (SANO) was well tolerated with no significant side effects and no impact on the ease of the operating urologist’s performance of the procedure."

Transrectal prostate biopsy is a common ambulatory procedure that can lead to anxiety and pain for some men. Low-dose, adjustable nitrous oxide is increasingly being used to improve the experience of care for patients undergoing painful procedures. Heidi J. Rayala, Division of Urologic Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts, and colleagues aimed to evaluate the safety and efficacy of low-dose (<45%) nitrous oxide, which has not been previously established for transrectal prostate biopsies.

For this purpose, they conducted a double-blind, prospective, single-institution, randomized, controlled trial on patients undergoing transrectal prostate biopsies. 133 patients were randomized to receive either self-adjusted nitrous oxide (n=66) or oxygen (n=67), in addition to routine periprostatic bupivacaine block.

At levels between 20% and 45%, nitrous oxide was adjusted to patients' desired effect. Patients completed a visual analog scale for anxiety, State-Trait Anxiety Inventory, and a visual analog scale for pain immediately before and after the biopsy. The blinded operating urologist evaluated the ease of the procedure.

The researchers assessed periprocedural vitals and complications. Patients were allowed to drive home independently.

The study revealed the following findings:

• There was no statistically significant difference in the primary anxiety endpoint of the State-Trait Anxiety Inventory or the visual analog scale for anxiety scores between the nitrous oxide and oxygen groups.
• Patients in the nitrous oxide group reported significantly lower visual analog scales for pain scores compared to the oxygen group.
• The operating urologists’ rating of tolerance of the procedure was better in the nitrous oxide group.
• There were no differences in biopsy performance time. Complications were similarly low between the two groups.

The findings of the study show that delivery of low-dose N2O titrated to the patient’s desired effect during transrectal prostate biopsy is safe and well tolerated, with a reduction of the patient’s pain during prostate biopsy, but no discernable impact on anxiety.

"These results indicate that the option of adjuvant N2O may improve patients’ experience of care as they undergo diagnostic evaluation for prostate cancer," the researchers concluded.

Reference:

Escobar AJ, Krishna S, Flowers KM, Abello A, Gershman B, Wagner AA, Chang P, Korets R, Mistretta CJ, Schreiber KL, Olumi AF, Rayala HJ. Practical Use of Self-Adjusted Nitrous Oxide During Transrectal Prostate Biopsy: A Double-Blind Randomized Controlled Trial. J Urol. 2024 Feb;211(2):214-222. doi: 10.1097/JU.0000000000003789. Epub 2023 Nov 20. PMID: 37984067.