Methemoglobinemia after topical anesthesia with lidocaine and benzocaine for a difficult intubation.

Methemoglobinemia is an uncommon cause of cyanosis; however, rapid diagnosis is critical to avoid potentially fatal consequences. Several local anesthetics can precipitate methemoglobinemia in susceptible patients. This case report of acute methemoglobinemia occurred during fiberoptic intubation in an awake patient without a past medical history of adverse reactions to local anesthetics.