Methemoglobinemia is characterized by increased quantities of methemoglobin. Methemoglobin is useless as an oxygen carrier and thus causes a varying degree of cyanosis. An 18-day-old girl weighing 3.2kg was referred to our department because of congenital teeth (upper and lower). The teeth were extracted under general anesthesia. To reduce bleeding, the surgeon injected 0.8m1 of 3% propitocaine with felypressin at the surgical site. After approximately 1.5hrs, the neonate became pale and cyanotic. Arterial blood gas analysis revealed a methemoglobin plasma concentration of 43.9%. Methylene blue was given at a total dose of 5mg, and the methemoglobin level improved to 2%. The subsequent course of the neonate was uneventful, and she was discharged in a satisfactory condition.
