Severe Methemoglobin Induced Hypoxemia Secondary to Transdermal Lidocaine Patch

Methemoglobinemia is a blood disorder in which the the iron of the heme group is in the ferric state (Fe3+), not in the ferrous state (Fe2+). This change in the hemoglobin molecule renders it incapable of carrying oxygen. The... [ view full abstract ]

Methemoglobinemia is a blood disorder in which the the iron of the heme group is in the ferric state (Fe3+), not in the ferrous state (Fe2+). This change in the hemoglobin molecule renders it incapable of carrying oxygen. The association between local anesthetics and methemoglobinemia is well known. Among the different local anesthetics, benzocaine and prilocaine appear to carry the most significant risk. Lidocaine induced methemoglobinemia is rare in current literature. In this case report, we describe a patient who developed severe methemoglobinemia secondary to the use of transdermal lidocaine patch for the management of postoperative pain. Other cases of transdermal lidocaine patch associated methemoglobinemia have been reported. However, this is the first case  of an adult with severe methemoglobinemia secondary to the use of transdermal lidocaine patch that resulted in life threatening hypoxemia.