Aniline-induced refractory methemoglobinemia in polytrauma: successful management with erythrocytapheresis

Methemoglobinemia is a life-threatening condition characterized by the inability of hemoglobin to transport oxygen efficiently. This case report describes acquired methemoglobinemia caused by exposure to aniline dye, which was successfully treated with erythrocytapheresis following the insufficient effect of methylene blue.

A 39-year-old male suffered multiple injuries, including burns and fractures, after falling into a barrel containing aniline. On site, emergency medical services (EMS) intubated the patient, performed chest decompression for pneumothorax, and decontaminated him before transferring him to a trauma centre. In the emergency unit, imaging revealed multiple rib, scapula, and pelvic fractures, retroperitoneal bleeding, and 15% total body surface area (TBS) burns. He was hemodynamically unstable, with metabolic acidosis, an oxygen saturation gap, and an initial methemoglobin level (MetHb) of 19%. Despite methylene blue treatment, the MetHb levels rose to undetectable levels (> 20%), and severe hemodynamic instability, refractory hypoxia, and metabolic derangement required the use of erythrocytapheresis.

Aniline exposure leads to the oxidation of ferrous iron (Fe2 +) in hemoglobin to ferric iron (Fe3 +), resulting in methemoglobinemia and impaired oxygen delivery. While methylene blue remains the first-line treatment, erythrocytapheresis proved effective in restoring tissue oxygenation in refractory methemoglobinemia complicated by hemorrhagic and traumatic shock.