Acquired methaemoglobinaemia — a case report

Methaemoglobinaemia is a rarely diagnosed, life-threatening pathology and involves the presence of more than 1% of oxidised haemoglobin in the blood that is unable to carry oxygen. We report the case of a 49-year-old male who developed fulminant symptoms of acute hypoxaemic respiratory failure and in whom acute and chronic cardiovascular and respiratory conditions had been ruled out. The discrepancy between oxygen saturation determined by pulse oximetry and oxygen saturation and oxygen partial pressure determined by capillary blood gas analysis, as well as the evident lack of response to oxygen therapy, were important indicators suggestive of a haemoglobinopathy and the diagnosis of methaemoglobinaemia. His methaemoglobin level was 16%. The symptoms resolved spontaneously and the causative factor was not identified.