A Case of Propitocaine-induced Methemoglobinemia During Extraction of Wisdom Teeth Under General Anesthesia

Abstract

Methemoglobinemia is characterized by increased methemoglobin in the circulating blood. Methemoglobin is useless as an oxygen carrier; thus, methemoglobinemia could lead to hypoxemia due to the limited availability of hemoglobin for oxygen delivery. A local anesthetic, propitocaine, is commonly used in dental surgery, and rarely causes methemoglobinemia. We report a case of a 21-year-old female who developed methemoglobinemia following the use of 3% propitocaine with 0.03U/ml felypressin during the extraction of wisdom teeth under general anesthesia. She suffered from long QT syndrome, and propitocaine was used to minimize the influence on hemodynamics. After the administration of propitocaine (total 378mg), pulse oxygen saturation (SpO₂) decreased to 93%. She was once ventilated with 100% oxygen; however, SpO₂ remained between 92–94% during the extraction. An arterial blood gas analysis revealed a methemoglobin value of 6.2%, leading to a diagnosis of methemoglobinemia. Oxygen therapy was administered and SpO₂ improved to 99% and methemoglobin values decreased to normal levels (1.0%) 11 hours after the end of the procedure. Oxygen therapy was completed and the subsequent course was uneventful. Clinicians should be aware that the use of propitocaine in dental surgery may cause methemoglobinemia and that when it occurs, appropriate treatment should be provided immediately.