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Sunday, February 22, 2009

Methemoglobinemia related to local anesthetics: a ...[Anesth Analg. 2009] - PubMed Result

Methemoglobinemia related to local anesthetics: a ...[Anesth Analg. 2009] - PubMed Result: "Chocolate-colored blood suggests methemoglobinemia but other colors may be found. A discrepancy between the pulse oximeter saturation (/=70 mm Hg) was present in 91.8% of the episodes. The difference between oxygen saturation measured by pulse oximetry and co-oximetry varied from -6.2% to 44.7%. Plain prilocaine may induce clinically symptomatic methemoglobinemia in children older than 6 mo at doses exceeding 2.5 mg/kg. In adults, the dose of prilocaine should be kept lower than 5.0 mg/kg, which is reduced to 3.2 mg/kg in the presence of renal insufficiency and to 1.3 mg/kg if other oxidizing drugs are used concurrently. A single spray of benzocaine may induce methemoglobinemia. Clinical symptoms may be observed at relatively low methemoglobin values, including coma at 32.2 and 29.1% in children and adults, respectively. Rebound methemoglobinemia (benzocaine on mucous membranes) with methemoglobin values as high as 59.9% may occur up to 18 h after methylene blue administration. Complications of methemoglobinemia include hypoxic encephalopathy, myocardial infarction, and death. CONCLUSION: Benzocaine should no longer be used. Prilocaine should not be used in children younger than 6-mo-old, in pregnant women, or in patients taking other oxidizing drugs. The dose should be limited to 2.5"