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METHEMOGLOBINEMIA TOXICITY FROM TOPICAL BENZOCAINE SPRAY

1995; Wiley; Volume: 43; Issue: 5 Linguagem: Inglês

10.1111/j.1532-5415.1995.tb06117.x

1532-5415

Joshua R. Shua‐Haim, Joel S. Gross,

Sympathectomy and Hyperhidrosis Treatments

To the Editor: Topical anesthetic sprays are used very commonly in various surgical and endoscopic procedures. They are usually free of any clinically significant toxicity. On rare occasions, however, near fatal toxicity can occur. Recently, we cared for a 77-year-old man with methemoglobinemia poisoning, likely due to benzocaine spray. This developed as a complication of the topical administration of benzocaine spray administered in preparation for upper gastrointestinal endoscopy for suspected reflux esophagitis. His methemoglobin level was 54.9%, with the arterial blood a deep burgundy color. After he was treated intravenously with 150 mg of methylene blue, his methemoglobin level was promptly reduced to 5.9%. Topical anesthetics are generally considered very safe and effective. They are sold in numerous over-the-counter preparations as well as for professional use only. Even though methemoglobinemia as a complication of topical anesthesia is rare, it is potentially fatal.1, 2 Taking into consideration the thousands of procedures performed daily in this country under local anesthesia, including benzocaine, it is likely that this complication will occur from time to time. In the case of our patient, the first source of reference was product labeling, which did not mention the possibility of adverse reactions such as methemoglobinema poisoning. We strongly opt for notation of this adverse reaction to be properly displayed on the product. In addition, methylene blue should be readily available to the physician administering such local anesthetics.