Methemoglobinemia: A Recurring Complication of Topical Benzocaine Spray

Abstract

Objective:

To report a case of acute methemoglobinemia in a patient undergoing a transesophageal echocardiogram (TEE) after administration of topical benzocaine spray.

Case Summary:

An 80-year-old white man with a history of coronary heart disease developed severe cyanosis one hour after a TTE. The patient was taken to the intensive care unit where he was diagnosed with acute methemoglobinemia. The patient was treated with methylene blue and successfully resuscitated. He recovered and was transferred out of the intensive care unit.

Discussion:

Acute methemoglobinemia is a problem that is infrequently encountered in clinical practice and, unless the practitioner is alert to the possible diagnosis, methemoglobinemia is capable of producing a potentially fatal outcome. The rise in bronchoscopies, endoscopies, and TEEs has resulted in an accompanying increase in reporting of acquired methemoglobinemia from benzocaine spray as well as other local anesthetics and medications. The drug of choice for treatment of methemoglobinemia is methylene blue administered at 1–2 mg/kg.

Conclusions:

Quick recognition, diagnosis, and prompt treatment with methylene blue are keys to a successful outcome.