Methemoglobinemia complicating topical lidocaine used during endoscopic procedures (original) (raw)

2001, The American Journal of Medicine

ethemoglobinemia results from the oxidation of ferrous iron to ferric iron within the hemoglobin molecule (1). Although there are many causes of this disorder, use of the local anesthetics benzocaine and prilocaine have been described as a rare cause of methemoglobinemia (2-4). We describe three cases of methemoglobinemia apparently due to topically applied lidocaine used before endoscopy. CASE 1 A 26-year-old woman with a history of human immunodeficiency virus infection presented with intermittent fever, cough, and dyspnea, which had persisted for several weeks. Chest roentgenography showed bilateral infiltrates. She was started on trimethoprim-sulfamethoxazole for presumed Pneumocystis carinii pneumonia. She was not taking antiretroviral medications. Bronchoscopy was performed, during which she received 10 cc of 2% lidocaine solution (Baxter Health Care Corporation, Glendale, CA) instilled into the trachea, two sprays of 2% lidocaine solution to the throat, and 2 cc of 2% lidocaine jelly (Astra USA, Westborough, MA) to each nostril. She also received 5 mg intravenous diazepam, 75 mg meperidine, and 0.6 mg atropine intramuscularly. After the procedure, she developed worsening dyspnea and cyanosis. On 100% oxygen, her arterial oxygen tension was 398 mm Hg, her oxygen saturation was 85%, and her methemoglobin level was 14%. Trimethoprim-sulfamethoxazole was discontinued, and the patient was observed in the intensive care unit. The next day, the patient's clinical condition improved. She was no longer in respiratory distress, and the cyanosis resolved (Table 1). The bronchoalveolar lavage did not reveal any opportunistic infection. She was subsequently discharged.