A rare case of anti-termite solution poisoning presenting as methaemoglobinaemia

Methaemoglobinaemia should be considered in all patients who are cyanotic and not responding to oxygen therapy. We report the case of a 25-year-old male who presented to the emergency room with alleged history of suicidal poisoning with 20 tablets of alprazolam (0.5mg) and anti-termite solution. At presentation he was drowsy, dyspnoeic and cyanosed. He was immediately intubated and intiated on mechanical ventilatory support. Oxygen saturation by pulse oximetry remained at 82% and did not improve even with a fraction of inspired oxygen of 1.0. Arterial blood was chocolate brown in colour. Arterial blood gas analysis revealed presence of significant saturation gap. Co-oxymetric analysis was done which revealed increased methaemoglobin levels following which methylene blue (100 mg) was given intravenously (IV) and symptoms improved. Patient was extubated the following day and was discharged in a haemodynamically stable state. Early diagnosis and antidotal treatment are pivotal in methaemoglobinaemia.