Case Report
Anesthetic Management of a Pediatric Patient with Congenital Methemoglobinemia
Table 1
Congenital methemoglobinemia: pathophysiology and classification.
| Disease subtypes | Pathophysiology | Features and prognosis |
| Cytochrome b5 reductase deficiency (type I) | Lack of cytochrome b5 reductase activity in erythrocytes only | Cyanosis develops at 6 to 9 months of age | Usually asymptomatic, even with levels up to 40 percent | Cytochrome b5 reductase deficiency (type II) | Altered cytochrome b5 reductase function in various tissues, notable for a decrease in oxygen supply to the central nervous system | Associated with developmental delay, failure to thrive Clinically, the most severe variant and usually fatal in the first year of life | Cytochrome b5 reductase deficiency (type III) | Decrease in functional cytochrome b5 reductase activity in all cell types | Cyanotic at birth, otherwise asymptomatic | Cytochrome b5 reductase deficiency (type IV) | Decrease in functional cytochrome b5 reductase activity in all cell types | Similar to type I | Hemoglobin M disease | Mutations of the globin gene (alpha, beta, or rarely gamma). This results in an Fe3+-phenolate complex that resists reduction. | Characterized by chronic cyanosis, otherwise asymptomatic |
|
|