Oxygen Therapy in Critical Illness

Precise Control of Arterial Oxygenation and Permissive Hypoxemia

Daniel Stuart Martin, BSc, MBChB, PhD, FRCA, FFICM; Michael Patrick William Grocott, MBBS, MD, FRCA, FRCP, FFICM


Crit Care Med. 2013;41(2):423-432. 

In This Article


Oxygen Delivery and PH

  • The safe lower limit of arterial oxygenation in critically ill patients is unknown, but may be less than accepted in clinical practice.

  • High fractional inspired concentrations of oxygen cause pulmonary damage, possibly more so in patients with injured lungs, but this damage is difficult to identify clinically and knowledge of safety thresholds for oxygen administration are unclear.

  • Precise control of arterial oxygenation in critically ill patients is a novel treatment strategy that we propose may improve outcomes by reducing the harm associated with unnecessary extremes of arterial oxygenation.

  • For selected critically ill patients, permissive hypoxemia (the tolerance of lower arterial oxygenation levels) may better balance the harms and benefits of oxygen therapy than attempting to achieve normoxemia.

  • Clinical evidence supporting permissive hypoxemia is not currently available and robust studies are required to evaluate safety and efficacy before implementation can be advocated.