Evaluation of Analgesic Effect of Equimolar Mixture of Oxygen and Nitrous Oxide Inhalation During Percutaneous Biopsy of Focal Liver Lesions: A Double-blind Randomized Study

Rationale and Objectives: Percutaneous liver biopsy for tumors performed under local anesthesia is still a painful procedure. The aim of this study was to evaluate the patient's reaction and the analgesic efficacy and safety of an equimolar mixture of oxygen and nitrous oxide (EMONO) inhalation. Materials and Methods: A monocenter, prospective, randomized and double-blind controlled study was performed including 99 adult patients undergoing ultrasound controlled liver biopsy for tumors. 50 patients received an EMONO and 49 patients received a placebo. Pain was evaluated by patients before and after the procedure using a Visual Analog Scale. Results: Analgesic control, defined by the difference between the final and initial VAS scores (A), was significantly better in the EMONO group than in the placebo group (Delta = 17.8 +/- 25.5 mm vs 30.1 +/- 32.6 mm; P = .045. The number of patients who would agree to undergo another liver biopsy under the same conditions was significantly higher in the EMONO group than the placebo group (92.0% vs 75.5%, P = .026). There were no side-effects from the administration of an EMONO. Conclusion: This study shows that patients receiving an EMONO had a higher analgesic control after percutaneous biopsy of focal liver lesions than patients in the placebo group. Moreover, acceptance of additional biopsies was higher in the EMONO group.