How Safe is Prilocaine as a Local Anesthetic in Children Younger Than 2 Years of Age: A Case Series

Abstract

INTRODUCTION[|]Methemoglobinemia is an urgent condition requiring early diagnosis and treatment; it may be fatal if the methemoglobin (MetHb) level is greater than 70% and tissue oxygenation is impaired. Prilocaine is a local anesthetic widely used during circumcision in children that has been associated with methemoglobinemia in therapeutic doses. Infants are vulnerable to hemoglobin oxidation because their cytochrome b5 reductase level is approximately 50% of adult values and fetal hemoglobin is more sensitive to oxidation than adult hemoglobin.[¤]METHODS[|]Six cases of methemoglobinemia occurring after the use of prilocaine during a circumcision are described. [¤]RESULTS[|]Six patients under the age of 2 years who had undergone prilocaine anesthesia were presented with cyanosis and a methemoglobin level of 35% to 50%. Four patients were treated with methylene blue as first-line therapy. In those 4 patients, cyanosis was resolved within 30 minutes in Case 1, an hour in Case 2, 2 hours in Case 3, and 4 hours in Case 5. In Case 3, the patient developed hemolysis following the methylene blue treatment. One patient was first treated with ascorbic acid due to a temporary shortage of methylene blue. The cyanosis improved in 1 hour and had regressed completely another hour later after a dose of methylene blue. In the final case, the cyanosis improved 30 minutes after intravenous administration of only ascorbic acid.[¤]DISCUSSION AND CONCLUSION[|]All of the patients were discharged healthy. Bupivacaine may be more appropriate than prilocaine as a local anesthetic in young children due to the risk of potentially severe methemoglobinemia side effect of prilocaine.[¤]

Keywords

• circumcision
• methemoglobinemia; prilocaine.