Oxygen Therapy in Acute Coronary Syndrome

Are the Benefits Worth the Risk?

Mony Shuvy; Dan Atar; Philippe Gabriel Steg; Sigrun Halvorsen; Sanjit Jolly; Salim Yusuf; Chaim Lotan

Disclosures

Eur Heart J. 2013;34(22):1630-1635. 

In This Article

Abstract and Introduction

Abstract

Oxygen supplementation is a standard treatment for all patients who present with acute coronary syndrome, regardless of oxygen saturation levels. Most of the data regarding the function of oxygen in myocardial infarction is based on a limited number of basic and clinical studies. We performed a systematic literature review that explores the basic and clinical data on the function of oxygen in ischaemic heart disease and myocardial infarction. This review discusses many aspects of oxygen treatment: (i) basic studies on the effects of oxygen in ischaemia and the potential cardiovascular effects of oxygen metabolites; (ii) clinical trials that have assessed the value of inhaled oxygen, supersaturated oxygen, and intracoronary injection of hyperoxaemic solutions in myocardial infarction; and (iii) the haemodynamic effects of oxygen in various clinical scenarios and its direct effects on the coronary vasculature. Our findings suggest that there are conflicting data on the effects of oxygen treatment. Further, the potential harmful effects of oxygen must be considered, particularly in myocardial infarction. These findings question the current guidelines and recommendations and emphasize the need for large clinical trials.

Introduction

Oxygen supplementation is a well-accepted therapy for hypoxaemic patients, because it increases the delivery of oxygen to cells and is thus believed to reverse the effects of hypoxia. Nevertheless, the value of oxygen therapy in patients with preserved oxygen saturation is unknown; further, it might even be hazardous under certain conditions (e.g.e.g. in pre-term neonates).[1,2]

Oxygen supplementation is a standard component of treatment in patients with acute heart disease. Hypoxaemic patients benefit from oxygen insufflation, because hypoxia can induce general and brain ischaemia.[3]

However, most patients who present with acute coronary syndrome (ACS) are not hypoxaemic,[4] and the value of oxygen therapy in these patients remains unknown.

The 2004 American (AHA/ACC) ST-elevation myocardial infarction (STEMI) guidelines recommend that oxygen be administered to hypoxaemic STEMI patients (SaO2 <90%, level of evidence B) and state that ''it is reasonable to administer supplemental oxygen to all patients during the first 6 hours" (level of evidence C).[5] More recently published updates do not address the administration of oxygen.[6]

The current European non-ST-elevation myocardial infarction (NSTEMI)-ACS guidelines recommend oxygen supplementation if oxygen saturation is <90%.[7] The recently published European STEMI guidelines suggest a different cut-off that defines hypoxia and advocate oxygen therapy only if oxygen saturation levels are <95%.[8] The recommendations in both guidelines are supported with a low level of evidence (C).

Awareness of the controversial effects of oxygen in normoxic ACS patients has increased,[9,10] an issue that the new guidelines address. However, the recommended practice remains unknown.

In this article, we systematically review basic data and animal and human studies that have assessed the effects of oxygen on cardiovascular parameters.

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