A case of drug-induced methemoglobinemia diagnosed on admission for trauma

Abstract

A 23-year-old woman with a history of refractory hives, for which she had been taking diaphenylsulfone (DDS) for 1 month, was transferred to our hospital because of a traffic accident. She had no dyspnea on admission, but her SpO₂ was low (92% on 10 L/min of O₂ with a reservoir mask). She had mild pain in her right chest; therefore, we suspected severe chest injury. However, computed tomography (CT) findings were normal. Blood gas analysis revealed a difference between SpO₂ (92%) and SaO₂ (98.8%), with 11.2% methemoglobinemia. She was diagnosed with methemoglobinemia caused by DDS, and DDS was discontinued. On the 5th day of admission, her methemoglobin level decreased to 4.0%, her SpO₂ increased to 97% (room air), and the difference between SpO₂ and SaO₂ improved. She was discharged on the 8th day of admission. It is necessary to consider the difference between SpO₂ and SaO₂ when SpO₂ is different from the clinical findings. Moreover, we must be aware that DDS can induce methemoglobinemia.