Patient-administered nitrous oxide/oxygen inhalation provides safe and effective analgesia for percutaneous liver biopsy: A randomized placebo-controlled trial

OBJECTIVE: Although percutaneous liver biopsy (PLB) can be a painful proced ure, common practice has not included intravenous sedation or analgesia. Pa tient-administered nitrous oxide/oxygen (N2O/O-2) inhalation has demonstrat ed analgesic efficacy in various procedures associated with mild to moderat e pain. The aim of this study was to investigate the safety and efficacy of analgesia with N2O/O-2 inhalation for PLB. METHODS: One hundred consecutive patients undergoing a first PLB (for chron ic hepatitis C: 56, for alcoholic liver disease: 23, for miscellaneous reas ons: 21). Patients were randomly assigned to self-administrate from a facia l mask with a demand valve, for 5 min before and during biopsy, either a br eathing mixture of 50% N2O/O-2 (N2O group, n = 51), or a breathing oxygen p lacebo (P group, n = 49). Liver biopsy was performed at bedside after adequ ate local anesthesia with xylocaine. At the end of the procedure, patients were asked to self-evaluate pain experienced using a visual analogue scale (VAS) with scoring from 0 to 100 mm. RESULTS: N2O/O-2 administration resulted in the absence of pain in a signif icantly higher number of patients treated than in patients of the P group: 19 versus 2, respectively (p 0.0001). Patients receiving N2O/O-2 had signif icantly lower pain scores than those of the P group: 12 +/- 12 versus 28 +/ - 19 mm (p < 0.0001). No serious complication was observed. Side effects of N2O/O-2 were minor and reversible. The average cost per biopsy was 4 US do llars. CONCLUSIONS: Patient-administered N2O/O-2 inhalation provides safe and effe ctive analgesia, at a reasonable cost, for PLB. Its routine use could be us eful for the management of patients with chronic liver disease undergoing P LB as it may enhance patients compliance with future biopsies. (C) 2001 by Am. Cell. of Gastroenterology.