The role of oxygenation during critical illness remains a major question.  Is extra oxygen harmful or helpful? What oxygen levels should we target, both for respiratory failure and for patients after cardiac arrest? Dr. Benjamin Abella discusses these topics, and reviews a hot-of-the-press work from European investigators (the “HOT-ICU”) trial, published in New England Journal of Medicine this month. The paper evaluates two different oxygen targets for patients with respiratory failure – implications for this work as it pertains to cardiac arrest will be discussed.   Key publications: Schjørring OL, Klitgaard TL, Perner A et al. Lower or Higher Oxygenation Targets for Acute Hypoxemic Respiratory Failure. NEJM 2021; Jan 20. doi: 10.1056/NEJMoa2032510. Roberts BW, Kilgannon JH, Hunter BR, et al. Association Between Early Hyperoxia Exposure After Resuscitation From Cardiac Arrest and Neurological Disability: Prospective Multicenter Protocol-Directed Cohort Study. Circulation. 2018 May 15;137(20):2114-2124. Kilgannon JH, Jones AE, Shapiro NI, Association between arterial hyperoxia following resuscitation from cardiac arrest and in-hospital mortality. JAMA. 2010 Jun 2;303(21):2165-71.