title: Effect of supplemental oxygen exposure on myocardial injury in ST-elevation myocardial infarction.
abstract: OBJECTIVE
  Supplemental oxygen therapy may increase myocardial injury following ST-elevation myocardial infarction (STEMI). In this study, we aimed to evaluate the effect of the dose and duration of oxygen exposure on myocardial injury after STEMI.
  
  
  METHODS
  Descriptive analysis of data from a multicentre, prospective, randomised, controlled trial of 441 patients with STEMI randomised to supplemental oxygen therapy or room air breathing. The primary endpoint was myocardial infarct size as assessed by cardiac biomarkers, troponin (cTnI) and creatine kinase (CK). Oxygen therapy was commenced by paramedics, and continued for up to 12 h postintervention in hospital. Supplemental oxygen exposure was calculated as the area under the dose×time curve for oxygen administration over the first 12 h, and then assessed for its association with cTnI/CK release using multivariable linear regression.
  
  
  RESULTS
  The median supplemental oxygen exposure was 1746 L (IQR: 960-2858). After adjustment for potential confounders, every 100 L increase in oxygen exposure in the first 12 h was associated with a 1.4% (95% CI 0.6% to 2.2%, p<0.001) and 1.2% (95% CI 0.7% to 1.8%, p<0.001) increase in the mean peak cTnI and CK, respectively. Excluding patients who developed cardiogenic shock, recurrent myocardial infarction or desaturations (SpO2<94%) during admission, every 100 L increase in oxygen exposure was associated with a 1.2% (95% CI 0.2% to 2.1%, p=0.01) and 1.0% (95% CI 0.3% to 1.7%, p=0.003) increase in the mean peak cTnI and CK, respectively. The median supplemental oxygen exposure of 1746 L would result in a 21% (95% CI 3% to 37%) increase in infarct size according to the cTnI profile.
  
  
  CONCLUSIONS
  Supplemental oxygen exposure in the first 12 h after STEMI was associated with a clinically significant increase in cTnI and CK release.
authors.affiliation: Department of Research and Evaluation, Ambulance Victoria, Melbourne, Australia Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
authors.forename: Ziad
authors.initials: Z
authors.lastname: Nehme
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Department of Cardiology, Alfred Hospital, Melbourne, Australia Hypertension and Cardiac Disease Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia Department of Cardiology, Western Health, Melbourne, Australia.
authors.forename: Dion
authors.initials: D
authors.lastname: Stub
authors.affiliation: Department of Research and Evaluation, Ambulance Victoria, Melbourne, Australia Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Department of Cardiology, Alfred Hospital, Melbourne, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Bernard
authors.affiliation: Department of Research and Evaluation, Ambulance Victoria, Melbourne, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Stephenson
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Department of Cardiology, Alfred Hospital, Melbourne, Australia.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Bray
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Department of Cardiology, Alfred Hospital, Melbourne, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Cameron
authors.affiliation: Monash Heart, Monash Medical Centre, Melbourne, Australia.
authors.forename: Ian T
authors.initials: IT
authors.lastname: Meredith
authors.affiliation: Department of Research and Evaluation, Ambulance Victoria, Melbourne, Australia.
authors.forename: Bill
authors.initials: B
authors.lastname: Barger
authors.affiliation: Department of Cardiology, Alfred Hospital, Melbourne, Australia Hypertension and Cardiac Disease Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: Andris H
authors.initials: AH
authors.lastname: Ellims
authors.affiliation: Department of Cardiology, Alfred Hospital, Melbourne, Australia Hypertension and Cardiac Disease Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Taylor
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Department of Cardiology, Alfred Hospital, Melbourne, Australia Hypertension and Cardiac Disease Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Kaye
authors.affiliation: Department of Research and Evaluation, Ambulance Victoria, Melbourne, Australia Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Discipline of Emergency Medicine, University of Western Australia, Western Australia, Australia.
authors.forename: Karen
authors.initials: K
authors.lastname: Smith
mesh_terms: D002423:Cause of Death / Q000639:trends; D003402:Creatine Kinase / Q000378:metabolism; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D009206:Myocardium / Q000378:metabolism*; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011446:Prospective Studies; D015996:Survival Rate / Q000639:trends; D016896:Treatment Outcome; D019210:Troponin I / Q000378:metabolism; D014739:Victoria / Q000453:epidemiology; D014904:Western Australia / Q000453:epidemiology
chemical_list: D019210:Troponin I; D003402:Creatine Kinase