Methemoglobinemia
Methemoglobinemia
• Excessive use of benzocaine (Hurricane) spray can lead to methemoglobinemia (M)
• The symptoms are brown-colored blood, low oxygen saturation readings, gray nailbeds, and pale lips
• Treatment is with methylene blue (1 mg/kg)
• There is no apparent correlation between the color of the skin or blood and the M concentration.
• Chocolate-colored blood is suggestive of M, but its absence does not exclude it
• Four local anesthetics can cause M — prilocaine, benzocaine, lidocaine, tetracaine.
• Methylene blue is ineffective as an antidote in patients with glucose-6-phosphodiesterase deficiency.
• Ascorbic acid can also be used to treat M, but it works more slowly
• Rebound M can occur up to 18 hours after cessation of methylene blue therapy
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