Case report of an infant who developed methemoglobinemia after lidocaine/propitocaine cream application

Abstract

Lidocaine/propitocaine cream (EMLA^® cream) is used in skin laser irradiation therapy and for pain relief arising during injection and from indwelling venous cannulae. We report the case of a 1-month-old girl who experienced methemoglobinemia after administration of this drug and required intensive care management. The symptoms improved with administration of methylthioninium, and she was discharged without neurological sequelae. To our knowledge, there are no previous reports of methemoglobinemia caused by the application of this drug in Japan. As our patient was a young infant, the cytochrome-b₅ reductase activity that reduces methemoglobin was lower than that of adults, and there are easily oxidizable fetal hemoglobin. It was thought that lidocaine and propitocaine, and their metabolism caused methemoglobinemia against this background. Attention is required in the use of lidocaine/propitocaine cream for neonates and young infants, and it should be used according to age-adapted dose and application time. With the occurrence of central cyanosis that does not improve even with oxygen administration, or when there is a discrepancy between SaO₂ and SpO₂, it is necessary to consider methemoglobinemia.