Objective: The objective of this study was to evaluate the analgesic and anxiolytic properties of an equimolar nitrous oxide-oxygen mixture (Entonox) for transrectal prostate biopsies compared with the use of intrarectal lidocaine gel. The authors evaluated the pain experienced by patients during the procedure and the correlation between pain and anxiety.
Material and methods: One hundred and two patients were included in the study and were divided into two groups. Patients of group 1 (47 patients) received 15 ml of intrarectal 2% lidocaine gel and patients of group 2 (55 patients) inhaled Entonox for three minutes before the procedure. A visual analogue scale (VAS), graduated from 0 to 10, was used to evaluate pain intensity. Patients completed the Spielberger State-Trait Anxiety Inventory (forms Y and A), scored from 20 to 80, before the procedure.
Results: No significant difference in anxiety scores was observed between the two groups (p=0.85). In contrast, pain intensity evaluated by the patient tended to be lower in the Entonox group (mean VAS: 2.9 versus 3.5; p=0.10). A linear correlation was observed between the anxiety score and pain intensity in the lidocaine group (p=0.01), but not in the Entonox group (p=0.92).
Conclusion: The use of Entonox tended to improve the tolerability of prostate biopsies, which can be explained by attenuation of the anxiogenic component of pain.