Context

Hypoxia is common in patients presenting to the ED and can be life-threatening. The differentials are wide and include cardiac, respiratory and haematological causes.

Methaemoglobinaemia accounts for only a small proportion of these cases and so the diagnosis is often delayed or missed. A thorough history, examination and analysis of investigations leads to the diagnosis. Early treatment can reverse methaemoglobinaemia within the hour, reducing subsequent morbidity and mortality. As such, it is essential for the ED physician to be familiar with the presentation and management of this uncommon but potentially reversible condition.

Learning bite

Methaemoglobinaemia is an uncommon but fully reversible cause of hypoxia – early diagnosis and treatment is essential.