From the Guidelines

Methemoglobinemia management primarily involves administering methylene blue.

Methylene blue is the first-line treatment, with a recommended dose of 1-2 mg/kg infused intravenously over 3 to 5 minutes, which can be repeated if symptoms do not resolve within 30-60 minutes 1.
Exchange transfusion may be considered in patients who do not respond to methylene blue, with a reported survival rate of 81.6% in patients refractory to methylene blue 1.
Hyperbaric oxygen therapy may also be used as an adjunctive treatment, although its use may be impractical in the setting of cardiopulmonary collapse or cardiac arrest 1.
Ascorbic acid is not recommended as a primary treatment, but may be used as an adjunctive therapy in some cases 1.
N-acetylcysteine is not recommended for the treatment of methemoglobinemia 1.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency should be considered, as methylene blue may not be effective and may cause hemolysis in these patients 1.
Pregnant patients require a multidisciplinary approach to treatment, weighing the risks of hypoxia on the baby and the teratogenic effects of methylene blue 1.
Monitoring of methemoglobin levels and oxygen saturation is crucial in the management of methemoglobinemia, particularly in symptomatic patients 1.

From the Research

The management of methemoglobinemia involves several approaches, including:

Supportive therapy, such as oxygen administration and assessment for other toxic complications 2
Removal of the agent responsible for the disorder 3
Observation 3
In severe cases, treatment with methylene blue, a specific antidote 2, 4, 3
Therapeutic whole blood exchange (TWBE) as an alternative when methylene blue fails 5

Treatment options for methemoglobinemia depend on the severity of symptoms and the etiology of the disorder:

Mild cases may only require supportive therapy and observation 2, 6
Severe cases may require treatment with methylene blue 2, 4, 3
In cases where methylene blue is contraindicated or ineffective, TWBE may be considered 5

Important considerations in the management of methemoglobinemia include:

Prompt recognition of the disorder to provide opportune treatment 4
High degree of suspicion for diagnosis, especially in patients with cyanosis and low saturation (SpO2) without significant cardiopulmonary dysfunction 3
Co-oximetry as the gold standard for diagnosis 6, 3
Monitoring of blood levels of methemoglobin, especially in acute cases 3