title: Severe Nausea and Vomiting in the Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia II Trial.
abstract: BACKGROUND
  The Evaluation of Nitrous oxide in the Gas Mixture for Anesthesia II trial randomly assigned 7,112 noncardiac surgery patients to a nitrous oxide or nitrous oxide-free anesthetic; severe postoperative nausea and vomiting (PONV) was a prespecified secondary end point. Thus, the authors evaluated the association between nitrous oxide, severe PONV, and effectiveness of PONV prophylaxis in this setting.
  
  
  METHODS
  Univariate and multivariate analyses of patient, surgical, and other perioperative characteristics were used to identify the risk factors for severe PONV and to measure the impact of severe PONV on patient outcomes.
  
  
  RESULTS
  Avoiding nitrous oxide reduced the risk of severe PONV (11 vs. 15%; risk ratio [RR], 0.74 [95% CI, 0.63 to 0.84]; P < 0.001), with a stronger effect in Asian patients (RR, 0.55 [95% CI, 0.43 to 0.69]; interaction P = 0.004) but lower effect in those who received PONV prophylaxis (RR, 0.89 [95% CI, 0.76 to 1.05]; P = 0.18). Gastrointestinal surgery was associated with an increased risk of severe PONV when compared with most other types of surgery (P < 0.001). Patients with severe PONV had lower quality of recovery scores (10.4 [95% CI, 10.2 to 10.7] vs. 13.1 [95% CI, 13.0 to 13.2], P < 0.0005); severe PONV was associated with postoperative fever (15 vs. 20%, P = 0.001). Patients with severe PONV had a longer hospital stay (adjusted hazard ratio, 1.14 [95% CI, 1.05 to 1.23], P = 0.002).
  
  
  CONCLUSIONS
  The increased risk of PONV with nitrous oxide is near eliminated by antiemetic prophylaxis. Severe PONV, which is seen in more than 10% of patients, is associated with postoperative fever, poor quality of recovery, and prolonged hospitalization.
authors.affiliation: From the Department of Anaesthesia and Perioperative Medicine, Alfred Hospital, Monash University, Melbourne, Victoria, Australia (P.S.M.); Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, People's Republic of China (M.T.V.C.); Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia (J.K., A.F.); Department of Anaesthesia and Pain Medicine, Royal Perth Hospital, Perth, Australia (M.J.P.); School of Medicine and Pharmacology, The University of Western Australia, Perth, Australia (M.J.P.); Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia (K.L.); Anaesthesia, Perioperative and Pain Medicine Unit, University of Melbourne, Melbourne, Victoria, Australia (K.L.); Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Victoria, Australia (K.L.); Department of Surgery, Austin Hospital, University of Melbourne, Melbourne, Australia (P.J.P.); Institute for Breathing and Sleep, Victoria, Australia (P.J.P.); Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio (D.I.S.); Department of Anaesthesia, Intensive Care and Pharmacology, Geneva University Hospitals, University of Geneva, Switzerland (G.H.); Department of Anesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada (W.S.B.); Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada (W.S.B.); Department of Anesthesia, Perioperative and Acute Pain Management, Barwon Health, Geelong, Victoria, Australia (C.O.); and Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, United Kingdom (J.R.S.).
authors.forename: Paul S
authors.initials: PS
authors.lastname: Myles
authors.forename: Matthew T V
authors.initials: MT
authors.lastname: Chan
authors.forename: Jessica
authors.initials: J
authors.lastname: Kasza
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Paech
authors.forename: Kate
authors.initials: K
authors.lastname: Leslie
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Peyton
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Sessler
authors.forename: Guy
authors.initials: G
authors.lastname: Haller
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
authors.forename: Cameron
authors.initials: C
authors.lastname: Osborne
authors.forename: J Robert
authors.initials: JR
authors.lastname: Sneyd
authors.forename: Andrew
authors.initials: A
authors.lastname: Forbes
mesh_terms: D000368:Aged; D000762:Anesthesia Recovery Period; D000769:Anesthesia, Inhalation / Q000009:adverse effects*; D018685:Anesthetics, Inhalation / Q000009:adverse effects*; D000932:Antiemetics / Q000627:therapeutic use; D044466:Asian People; D013505:Digestive System Surgical Procedures / Q000009:adverse effects; D023381:Endpoint Determination; D005260:Female; D005334:Fever / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008136:Longevity; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000009:adverse effects*; D011183:Postoperative Complications / Q000453:epidemiology; D020250:Postoperative Nausea and Vomiting / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D016896:Treatment Outcome; D044465:White People
chemical_list: D018685:Anesthetics, Inhalation; D000932:Antiemetics; D009609:Nitrous Oxide