Review
Oxygen Therapy for Acute Myocardial Infarction—Then and Now. A Century of Uncertainty

https://doi.org/10.1016/j.amjmed.2011.04.034Get rights and content

Abstract

For about 100 years, inhaled oxygen has been administered to all patients suspected of having an acute myocardial infarction. The basis for this practice was the belief that oxygen supplementation raised often-deficient arterial oxygen content to improve myocardial oxygenation, thereby reducing infarct size. This assumption is conditional and not evidence-based. While such physiological changes may pertain in some patients who are hypoxemic, considerable data suggest that oxygen therapy may be detrimental in others. Acute oxygen therapy may raise blood pressure and lower cardiac index, heart rate, cardiac oxygen consumption, and blood flow in the cerebral and renal beds. Oxygen also may lower capillary density and redistribute blood in the microcirculation. Several reports now confirm that these changes occur in humans. In patients with both acute coronary syndromes and stable coronary disease, oxygen administration may constrict the coronary vessels, lower myocardial oxygen delivery, and may actually worsen ischemia. There are no large, contemporary, randomized studies that examine clinical outcomes after this intervention. Hence, this long-accepted but potentially harmful tradition urgently needs reevaluation. Clinical guidelines appear to be changing, favoring use of oxygen only in hypoxemic patients, and then cautiously titrating to individual oxygen tensions.

Section snippets

Early Laboratory and Clinical Trials

After Steele successfully used inhaled oxygen to relieve angina in 1900,4 the practice endured, based upon the popular notion that administered oxygen increased oxygen delivery to the myocardium and reduced infarct size.5, 6 Fifty years later Russek et al7 found that 100% oxygen given by mask not only failed to relieve or modify angina, but accentuated and prolonged some electrocardiographic changes of ischemia. They postulated that hyperoxic blood prevented reactive hyperemia in ischemic

Hemodynamic Effects of Oxygen and Myocardial Oxygen Availability

Oxygen is a vasoactive substance, and the hemodynamic effects upon healthy subjects and patients with AMI are fairly well known. Acute oxygen administration may raise blood pressure13 and lower cardiac index, heart rate, and cardiac oxygen consumption.14, 15 Coronary blood flow falls in response to hyperoxia-induced vasoconstriction regardless of initial saturation.16 Oxygen-induced vasoconstriction may similarly lower cerebral17 and renal blood flow.18 Thomas et al19 found that 40% oxygen

Systematic Reviews

Several systematic reviews of the effects of oxygen in patients with CHD are available. In 2004, a review of 9 trials failed to demonstrate effectiveness because of insufficient evidence.30 In 2008, Wijesinghe et al31 identified 51 studies, but only 2 met inclusion criteria of substantive clinical outcomes. It was concluded that evidence was limited, but primarily using the trial results of Rawles and Kenmure,11 support for oxygen therapy in all patients with uncomplicated AMI was lacking, and

What the Guidelines Say

Of guidelines that no longer recommend oxygen for all AMI patients, one of the first was the British Thoracic Society Guideline for Emergency Oxygen use, in which oxygen was recommended only for hypoxemic patients.39 The National Institute for Health and Clinical Excellence (NICE) Guideline on the management of chest pain of suspected cardiac origin, the UK Ambulance Service oxygen guideline, and a number of other societies subsequently adopted similar advice.40, 41, 42 The NICE guideline

Conclusion

Oxygen is a vasoactive drug and should be prescribed only when indicated. The burden of proof properly falls on the intervention, and there is no large, contemporary, randomized study available. Evidence supporting use of oxygen in patients suspected of having an AMI who are normoxemic is of poor quality and now old, predating modern trial methods, reperfusion, and other advances in management. Recent data suggest that physiological evidence of harm is strong, clinical evidence of harm is weak,

References (51)

  • C. Steele

    Severe angina pectoris relieved by oxygen inhalations

    BMJ

    (1900)
  • W.M. Boothby et al.

    One hundred percent oxygen: indications for its use and methods of its administration

    JAMA

    (1939)
  • E.W. Boland

    Oxygen in high concentrations for relief of pain in coronary thrombosis and severe angina pectoris

    JAMA

    (1940)
  • Russek HI, Regan FD, Naegele CF. One hundred percent oxygen in the treatment of acute myocardial infarction and severe...
  • P.R. Maroko et al.

    Reduction of infarct size by oxygen inhalation following acute coronary occlusion

    Circulation

    (1975)
  • J.E. Madias et al.

    Reduction of precordial ST-segment elevation in patients with anterior myocardial infarction by oxygen breathing

    Circulation

    (1976)
  • M. Horvat et al.

    Effect of oxygen breathing on pacing-induced angina pectoris and other manifestations of coronary insufficiency

    Circulation

    (1972)
  • J.M. Rawles et al.

    Controlled trial of oxygen in uncomplicated myocardial infarction

    Br Med J

    (1976)
  • A.T. Wilson et al.

    Hypoxaemia and supplemental oxygen therapy in the first 24 hours after myocardial infarction: the role of pulse oximetry

    J R Coll Physicians Lond

    (1997)
  • W.S. Waring et al.

    Cardiovascular effects of acute oxygen administration in healthy adults

    J Cardiovasc Pharmacol

    (2003)
  • W. Ganz et al.

    Coronary hemodynamics and myocardial oxygen metabolism during oxygen breathing in patients with and without coronary artery disease

    Circulation

    (1972)
  • A.J. Thomson et al.

    Effects of short-term isocapnic hyperoxia and hypoxia on cardiovascular function

    J Appl Physiol

    (2006)
  • S.S. Kety et al.

    The effects of altered arterial tensions of carbon dioxide and oxygen on cerebral blood flow and cerebral oxygen consumption in normal young men

    J Clin Invest

    (1948)
  • G.M. Aber et al.

    The effect of acute changes in inspired oxygen concentration on cardiac, respiratory and renal function in patients with chronic obstructive airways disease

    Clin Sci

    (1964)
  • M. Thomas et al.

    Haemodynamic effects of oxygen in patients with acute myocardial infarction

    Br Heart J

    (1965)

    • Cited by (34)

    • Oxygen Supplementation and Hyperoxia in Critically Ill Cardiac Patients: From Pathophysiology to Clinical Practice

      2022, JACC: Advances

    • Routine Supplementary Oxygen for Myocardial Infarction: From Unsettled to Unsettling

      2020, JACC: Cardiovascular Interventions

    • DETermination of the role of OXygen in suspected Acute Myocardial Infarction trial

      2014, American Heart Journal
      Citation Excerpt :

      Furthermore, acceptance from the medical community to challenge a “common knowledge” has been questioned,28 and the study has therefore been difficult to undertake. However, the issue is nowadays frequently discussed in various articles, blogs, and reviews, which could indicate a changing attitude.28-34 Since 2012, 2 RCTs have been started investigating oxygen therapy in STEMI patients; the Australian AVOID study35 is aiming to include 490 patients looking at infarct size by cardiac biomarkers as primary end point, whereas the Swedish SOCCER trial assesses myocardial salvage index by cardiac magnetic resonance imaging in 100 patients.36

    • Oxygen requirements for acutely and critically III patients

      2017, Critical Care Nurse

    • Implementation of a titrated oxygen protocol in the out-of-hospital setting

      2014, Prehospital and Disaster Medicine

    • Mathematical Modeling Of Stem Cell Therapy For Left Ventricular Remodeling After Myocardial Infarction

      2023, Journal of Mechanics in Medicine and Biology
    View all citing articles on Scopus

    Funding: None.

    Conflict of Interest: None.

    Authorship: The author is solely responsible for the entire content of this review.

    View full text
    Copyright © 2011 Elsevier Inc. All rights reserved.