The potential dangers of hyperoxia need to be recognised

Oxygen is cheap, widely available, and used in a range of settings and conditions to relieve or prevent tissue hypoxia. Since its discovery by Scheele and Priestley in the 1770s, it has remained one of the most effective therapeutic agents available. However, as a result of poor prescribing and monitoring, inappropriate doses are often given.1

Oxygen is most commonly delivered by devices with variable performance such as face masks and nasal cannulae. These can produce unexpectedly high concentrations of inspired oxygen, particularly when ventilation is depressed.2 In addition, masks that incorporate a reservoir bag are often used in emergencies, following the widespread adoption of advanced trauma life support style (or ATLS) guidelines. These appliances can produce systemic hyperoxia that is generally assumed to be harmless. However, emerging evidence suggests that for some patients with acute medical conditions, hyperoxia may be harmful.

Oxygen therapy is often …