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, Sh e was treated with 5 mg of midazolam and benzocaine topical anesthetic spray prior to undergoing colonoscopy and esophageal gastroduodenosco py. Thirty minutes after endoscopy, the patient became cyanotic and dy spneic; 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 norm al saline solution, the cyanosis and dyspnea resolved.