Surviving fatal Methemoglobinemia

Abstract

Background: Methemoglobinemia is one of the rare causes of cyanosis, encountered in the Emergency Department. It can be congenital or acquired, affecting the oxygen binding capacity of hemoglobin, thus shifting the oxyhemoglobin dissociation curve to the left. It is potentially life-threatening, but it responds well to specific therapies, if recognized and intervened early. MetHb levels >70% are often described as incompatible with life.Case: Here, we describe two cases of near-fatal MH (MetHb levels >70%), one with intentional and the other with accidental ingestion of substance-producing MH, and its management which highlights how timely diagnosis and prompt appropriate treatment in the Emergency Department can be lifesaving. Both cases were at physiological extremes on arrival to the ED. However, the early clinical suspicion and prompt diagnosis of methemoglobinemia, which was confirmed by blood co-oximetry, helped expedite the delivery of specific anti-dote for methemoglobin, i.e., intravenous methylene blue. Both patients responded well to the treatment and were hemodynamically stable within 6 hoursConclusion: Cyanosis, which does not respond to oxygen, and low saturation levels not responding to oxygen therapy should raise the suspicion of Methemoglobinemia (MH). Early diagnosis and prompt administration of methylene blue are the key factors for survival.

Keywords

• methemoglobinemia
• methylene blue
• cyanosis
• sodium nitrite
• oxyhemoglobin dissociation curve