title: Patient-administered nitrous oxide/oxygen inhalation provides safe and effective analgesia for percutaneous liver biopsy: a randomized placebo-controlled trial.
abstract: OBJECTIVE
  Although percutaneous liver biopsy (PLB) can be a painful procedure, common practice has not included intravenous sedation or analgesia. Patient-administered nitrous oxide/oxygen (N2O/O2) inhalation has demonstrated analgesic efficacy in various procedures associated with mild to moderate pain. The aim of this study was to investigate the safety and efficacy of analgesia with N2O/O2 inhalation for PLB.
  
  
  METHODS
  One hundred consecutive patients undergoing a first PLB (for chronic hepatitis C: 56, for alcoholic liver disease: 23, for miscellaneous reasons: 21). Patients were randomly assigned to self-administrate from a facial mask with a demand valve, for 5 min before and during biopsy, either a breathing mixture of 50% N2O/O2 (N2O group, n = 51), or a breathing oxygen placebo (P group, n = 49). Liver biopsy was performed at bedside after adequate 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/O2 administration resulted in the absence of pain in a significantly higher number of patients treated than in patients of the P group: 19 versus 2, respectively (p = 0.0001). Patients receiving N2O/O2 had significantly 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/O2 were minor and reversible. The average cost per biopsy was 4 US dollars.
  
  
  CONCLUSIONS
  Patient-administered N2O/O2 inhalation provides safe and effective analgesia, at a reasonable cost, for PLB. Its routine use could be useful for the management of patients with chronic liver disease undergoing PLB as it may enhance patients compliance with future biopsies.
authors.affiliation: Service des Maladies du Foie et de l'Appareil Digestif, H pital de Bicêtre, Université Paris-Sud, Le Kremlin-Bicêtre, France.
authors.forename: L
authors.initials: L
authors.lastname: Castéra
authors.forename: I
authors.initials: I
authors.lastname: Nègre
authors.forename: K
authors.initials: K
authors.lastname: Samii
authors.forename: C
authors.initials: C
authors.lastname: Buffet
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D016058:Analgesia, Patient-Controlled / Q000009:adverse effects / Q000191:economics / Q000592:standards; D001706:Biopsy / Q000379:methods*; D004338:Drug Combinations; D005260:Female; D017048:Health Care Costs; D006801:Humans; D008099:Liver / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000009:adverse effects / Q000627:therapeutic use*; D010100:Oxygen / Q000009:adverse effects / Q000627:therapeutic use*; D012449:Safety
chemical_list: D004338:Drug Combinations; D009609:Nitrous Oxide; D010100:Oxygen