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Good Morning and Welcome Applicants

Good Morning and Welcome Applicants. February 3, 2010. Methemoglobinemia. Normal Fe +2 to Fe 3+ Oxidation Fe 3+ is unable to bind oxygen Remaining Fe has higher O 2 affinity Impaired O 2 delivery to tissues Rare cause of cyanosis. Methemoglobinemia. Hereditary

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Good Morning and Welcome Applicants

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  1. Good Morning andWelcome Applicants February 3, 2010

  2. Methemoglobinemia • Normal Fe+2 to Fe3+ • Oxidation • Fe3+ is unable to bind oxygen • Remaining Fe has higher O2 affinity • Impaired O2 delivery to tissues • Rare cause of cyanosis

  3. Methemoglobinemia • Hereditary • NADH cytochrome b5 reductase deficiency • AR • Hemoglobin M disease • AD • Structural alteration of alpha or beta globin chains

  4. Methemoglobinemia • Acquired • Exogenous agents that increase methemoglobin formation • Topical anesthetic agents • Benzocaine • Acute diarrhea and metabolic acidosis • Babies 2-6 months • Abnormal absorption of nitrites

  5. Methemoglobinemia • Presentation • Cyanosis (8-12%) • 30-50% • Dyspnea • Dizziness • Tachycardia • Fatigue • HA

  6. Methemoglobinemia • Presentation • 50-70% • Severe lethargy • Stupor • >70% • Death • Congenital • Asymptomatic

  7. Methemoglobinemia • Suspicion • Clinical cyanosis • Normal arterial pO2 • “chocolate brown blood” • Pulse oximetry unreliable

  8. Methemoglobinemia • Diagnosis • Co-oximetry • Respiratory therapy • False positives with methylene blue with some methods • Genetic testing

  9. Methemoglobinemia • Treatment - Acquired • Recognition and discontinuation of offending agents • Symptomatic or >20% • Methylene blue 1-2mg/kg • May repeat 1 hr later (max dose 7mg/kg) • Reducing agents • Ascorbid acid • Glutathione • Riboflavin

  10. Methemoglobinemia • Treatment • G6PD deficiency • May not respond to treatment • Other • Hyperbaric oxygen • Exchange Transfusion

  11. Methemoglobinemia • Lessons • Always consider in differential diagnosis of cyanosis • Caution with use of topical anesthetics • History • Cyanosis • Blue nail beds • Blue lips • Family History

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