Methemoglobinemia induced by topical anesthetic (benzocaine).

Methemoglobinemia is a condition in which more than 2% of the hemoglobin of the blood has been oxidized to the ferric form, a molecule which is incapable of binding oxygen or carbon dioxide. Clinically, the patient appears lethargic, cyanotic, and does not respond to oxygen. We describe a patient with esophageal carcinoma who developed severe methoglobinemia following application of benzocaine in spray for local anesthesia prior to intraluminal irradiation. Review of the literature is presented.