Proposal for more judicious use of oxygen therapy

By measurement of partial pressure of oxygen (pO₂) and oxygen saturation (sO₂), arterial blood gas analysis provides the gold standard method for assessment of blood oxygenation and the means for monitoring supplemental oxygen therapy. More frequent use of arterial blood gases for this purpose will be required if the proposed novel strategies for management of hypoxemia, contained in a recent review article, are adopted. 

The authors of this article argue for a more restrictive and more closely controlled use of supplemental oxygen therapy among the critically ill. A premise of their argument is that current medical practice in this area tends to emphasize the importance of supplemental oxygen therapy for avoiding tissue hypoxemia and downplays the potential risks that such therapy poses. 

The potentially toxic effect of inspiring high oxygen concentration is effectively ignored in the quest of avoiding tissue hypoxia. The authors suggest that more precise control of arterial oxygenation with better patient-defined targets of arterial pO₂ and sO₂, along with the adoption of a policy of permissive hypoxemia for some patients may allow avoidance of both tissue hyperoxia and tissue hypoxia. 

In support of these proposals, this review article includes discussion of many topics including: the causes and time course of hypoxemia; the harmful (toxic) effects of both hyperoxemia and hypoxemia; and the physiological adaptations to hypoxemia that protect cell function and viability. 

There is discussion of evidence that in particular cases even the most profound hypoxemia is survivable (the lowest reported pO₂(a) is apparently 1.0 kPa (7.5 mmHg) occurring in a 22-year-old male heroin-overdose patient breathing room air). 

The authors concede that a safe lower limit of arterial oxygenation in critically ill patients remains to be established but the evidence suggests that it may well be lower than that currently used as a target for oxygen therapy. It may be safer to allow some degree of hypoxemia in order to avoid the toxic effects of oxygen.

In conclusion, the authors acknowledge the necessity for more research for their proposals to be accepted and implemented. An interesting and supportive accompanying editorial describes the article: “thought-provoking”.