title: Perioperative hyperoxia - Long-term impact on cardiovascular complications after abdominal surgery, a post hoc analysis of the PROXI trial.
abstract: BACKGROUND
  Increased long-term mortality was found in patients exposed to perioperative hyperoxia in the PROXI trial, where patients undergoing laparotomy were randomised to 80% versus 30% oxygen during and after surgery. This post hoc follow-up study assessed the impact of perioperative hyperoxia on long-term risk of cardiovascular events.
  
  
  METHODS
  A total of 1386 patients undergoing either elective or emergency laparotomy were randomised to 80% versus 30% oxygen during and two hours after surgery. At follow-up, the primary outcome of acute coronary syndrome was assessed. Secondary outcomes included myocardial infarction, other heart disease, and acute coronary syndrome or death. Data were analysed in the Cox proportional hazards model.
  
  
  RESULTS
  The primary outcome, acute coronary syndrome, occurred in 2.5% versus 1.3% in the 80% versus 30% oxygen group; HR 2.15 (95% CI 0.96-4.84). Patients in the 80% oxygen group had significantly increased risk of myocardial infarction; HR 2.86 (95% CI 1.10-7.44), other heart disease; HR 1.40 (95% 1.06-1.83), and acute coronary syndrome or death; HR 1.22 (95% CI 1.01-1.49).
  
  
  CONCLUSIONS
  Perioperative hyperoxia may be associated with an increased long-term risk of myocardial infarction and other heart disease.
authors.affiliation: Centre for Perioperative Optimisation, Department of Surgery, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, DK-2730 Herlev, Denmark. Electronic address: siv.fonnes@gmail.com.
authors.forename: Siv
authors.initials: S
authors.lastname: Fonnes
authors.affiliation: Department of Surgery, Køge Hospital, University of Copenhagen, Lykkebækvej 1, DK-4600 Køge, Denmark. Electronic address: igo@regionsjaelland.dk.
authors.forename: Ismail
authors.initials: I
authors.lastname: Gögenur
authors.affiliation: Department of Anaesthesiology, Slagelse Hospital, Fælledvej 11, DK-4200 Slagelse, Denmark. Electronic address: edith_00@hotmail.com.
authors.forename: Edith Smed
authors.initials: ES
authors.lastname: Søndergaard
authors.affiliation: The Research Unit for General Practice and Section of General Practice, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, DK-1014 Copenhagen C, Denmark. Electronic address: siersma@sund.ku.dk.
authors.forename: Volkert Dirk
authors.initials: VD
authors.lastname: Siersma
authors.affiliation: Digestive Disease Centre, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Bispebjerg Bakke 23, DK-2400 Copenhagen, NV, Denmark. Electronic address: larsnjorgensen@hotmail.com.
authors.forename: Lars Nannestad
authors.initials: LN
authors.lastname: Jorgensen
authors.affiliation: Copenhagen Trial Unit, Centre for Clinical Intervention Research, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen E, Denmark. Electronic address: wetterslev@ctu.dk.
authors.forename: Jørn
authors.initials: J
authors.lastname: Wetterslev
authors.affiliation: Department of Anaesthesiology, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark. Electronic address: christianmeyhoff@gmail.com.
authors.forename: Christian Sahlholt
authors.initials: CS
authors.lastname: Meyhoff
mesh_terms: D000005:Abdomen / Q000601:surgery*; D054058:Acute Coronary Syndrome / Q000453:epidemiology* / Q000209:etiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D018496:Hyperoxia / Q000150:complications* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology; D059035:Perioperative Period
keywords: Acute coronary syndrome; Heart disease; Laparotomy; Operative; Oxygen inhalation therapy; Surgical procedures