When is inpatient treatment indicated for methemoglobinemia?

Updated: Dec 09, 2018
  • Author: Mary Denshaw-Burke, MD, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Prompt recognition of the condition and initiation of treatment, as indicated (especially in acquired methemoglobinemia), are critical in the management of methemoglobinemia. However, at the same time, it may be imperative to initiate extensive and sometimes invasive investigations to rule out cardiac and pulmonary abnormalities that often result in a similar clinical picture with cyanosis. Once the diagnosis is confirmed, management should be instituted as indicated. Initial care includes administration of supplemental oxygen and removal of the offending oxidizing substance.

Patients with methemoglobinemia who have asymptomatic cyanosis resulting from ingestion of a known substance are the only patients who should be considered for early discharge. They may be discharged after a 6-hour observation period only if the implicated cause has been eliminated and is not known to cause rebound methemoglobinemia.

Symptomatic patients with methemoglobinemia or those with a significantly elevated methemoglobin level should be admitted to the hospital. A lower threshold for hospital admission should occur for patients with complicating factors, such as underlying anemia, chronic cardiopulmonary disease, or peripheral vascular disease. The specific symptoms determine the level of care that is needed.

Intravenous (IV) methylene blue is the first-line antidotal agent. Exchange transfusion and hyperbaric oxygen treatment are second-line options for patients with severe methemoglobinemia whose condition does not respond to methylene blue or who cannot be treated with methylene blue (eg, those with glucose-6-phosphate dehydrogenase [G6PD] deficiency).

Patient transfer should occur when life-threatening methemoglobinemia that is refractory to treatment occurs in a facility that cannot provide the appropriate critical care.

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