Abstract and Introduction
Introduction: Local anesthesia with prilocaine has become a routine part of ambulatory circumcision procedures. Methemoglobinemia is a rare but potentially lethal complication of local anesthetics.
Case presentation: We report the case of a 40-day-old Turkish boy who presented with cyanosis after receiving local anesthesia with prilocaine. His methemoglobin level revealed severe methemoglobinemia (methemoglobin = 44%). His cyanosis resolved after intravenous administration of methylene blue.
Conclusion: Although the association between prilocaine use and methemoglobinemia has generally restricted the use of prilocaine in babies, it is still widely used in ambulatory procedures, especially during circumcision in the neonatal period. Prilocaine should not be used in babies who are less than 3 months old because of the risk of methemoglobinemia; other local anesthetics may be used for this age group. Furthermore, general anesthesia by mask ventilation may be favored for babies less than 3 months of age instead of local anesthetics.
Circumcision is the surgical removal of the foreskin of the glans penis. Newborns undergoing circumcision demonstrate objective, measurable evidence of pain, yet the procedure is often performed without analgesia. Newborn circumcision is reported to be the most common elective surgical procedure performed on infants in the United States. There is still significant controversy regarding the benefits and risks of newborn circumcision. In recent years, a number of authors have reported medical benefits of newborn circumcision including a decrease in the number of infants with urinary tract infections, protection against penile cancer, protection against HIV infection and protection against transmission of human papilloma virus.
Anesthesia is not routinely administered for neonatal circumcision for a variety of reasons, for example, the relatively short duration of the intervention, the perceived lack of importance of the pain, and concerns regarding possible toxicity of the medication. Administration of anesthesia attenuates acute circumcision pain and can prevent or reduce some of the short-term and long-term behavioral effects. For many years, it has been suggested that newborn infants or neonates were unable to feel pain because of their immature nervous system. Nowadays, it is commonly accepted that newborn infants can feel pain and should be treated with that taken into consideration.
Local anesthesia infiltration by injection is considered to be the most effective method of analgesia for circumcision. The method most commonly used to administer the anesthetic is the dorsal penile nerve block (DPNB), first described in 1978. Local anesthesia with prilocaine has become a routine part of ambulatory circumcision procedures. Methemoglobinemia is a rare but potentially lethal complication of local anesthetics. The iron in hemoglobin is normally in the reduced, ferrous state (Fe2+), which is essential for its oxygen-transporting function. Under physiological conditions, there is a slow, constant loss of electrons to release oxygen and the ferric (Fe3+) form combines with water, producing methemoglobin. The predominant intracellular mechanism for the reduction of methemoglobin is cytochrome b5, and only 1 to 2% of hemoglobin is normally in the ferric state. As methemoglobin levels increase, oxygen delivery to tissues is impaired and cellular hypoxia develops. Infants are particularly vulnerable to hemoglobin oxidation because their cytochrome b5 reductase level is approximately 50% of the adult value. We report a patient with prilocaine-induced acquired methemoglobinemia and discuss the use of intravenous methylene blue treatment.
J Med Case Reports. 2010;4(1):49 © 2010 Ozdogan et al; licensee; BioMed Central, Ltd.
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Cite this: Methemoglobinemia Presenting in a Circumcised Baby Following Application of Prilocaine: A Case Report - Medscape - Feb 01, 2010.