Methemoglobinemia secondary to benzocaine topical anesthetic.
An 80-year-old white woman with a history of hypertension presented to the Emergency Department with bright red bleeding from the rectum. She was treated with 5 mg of midazolam and benzocaine topical anesthetic spray prior to undergoing colonoscopy and esophageal gastroduodenoscopy. Thirty minutes after endoscopy, the patient became cyanotic and dyspneic; she was suffering from methemoglobinemia, a rare complication secondary to the use of benzocaine topical anesthetic spray. After i.v. administration of methylene blue, 120 mg (2 mg/kg) in 100 cc of normal saline solution, the cyanosis and dyspnea resolved.
Lee
E
E
Department of Internal Medicine, Lehigh Valley Hospital, Allentown, Pennsylvania 18105-1556, USA.
Boorse
R
R
Marcinczyk
M
M
D000368:Aged; D000369:Aged, 80 and over; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000009:adverse effects*; D001566:Benzocaine / Q000008:administration & dosage / Q000009:adverse effects*; D016145:Endoscopy, Digestive System / Q000379:methods; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000175:diagnosis*; D006801:Humans; D008708:Methemoglobinemia / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology; D012007:Rectum
D000779:Anesthetics, Local; D001566:Benzocaine