Oxygen Therapy in Patients With Acute Heart Failure: Friend or Foe?

Supplemental oxygen, a therapy that has been used for more than a century, is recommended in all practice guidelines in the management of hypoxemic (peripheral oxygen saturation <90% to 94% or partial arterial oxygen pressure <60 mm Hg) patients with acute heart failure, but its use in normoxemic patients is controversial. Several pre-clinical and early clinical studies have shown the detrimental effects of oxygen therapy and subsequent hyperoxia in patients with normal oxygen saturation levels. These effects are suggested to be gauged by the increased production of reactive oxygen species and the related oxidative stress and by the reductions in coronary blood flow and myocardial oxygen consumption resulting from hyperoxia-induced vasoconstriction in the cerebral, coronary, and systemic vasculature. Considering these findings, recent practice guidelines are diverging from the previous consensus that oxygen should be administered routinely in patients with cardiac disease, but this new direction is also based on expert opinions rather than evidence such as well-designed trials. In this review, the authors summarize current evidence regarding the cardiovascular effects of supplemental oxygen therapy, particularly evidence from the field of acute heart failure, and delineate knowledge gaps in the field and future directions in research.