Hypoxemia sans hypoxemia.

Acquired methemoglobinemia usually occurs during endoscopy after exposure to a variety of drugs commonly used in critical care units and in endoscopy suites. A rapid infusion of methylene blue can result in a complete recovery of patients with a favorable prognosis. The authors describe a case of 31-year-old woman in whom methemoglobinemia developed with the use of benzocaine, and who showed complete recovery after methylene blue infusion. Hence, the availability of methylene blue in these settings is advocated.