Good Morning and Welcome Applicants
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Transcript of Good Morning and Welcome Applicants
Good Morning andWelcome Applicants
February 3, 2010
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
Methemoglobinemia• Hereditary
• NADH cytochrome b5 reductase deficiency• AR
• Hemoglobin M disease• AD• Structural alteration of alpha or beta
globin chains
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
Methemoglobinemia• Presentation
• Cyanosis (8-12%)• 30-50%
• Dyspnea• Dizziness• Tachycardia• Fatigue• HA
Methemoglobinemia• Presentation
• 50-70%• Severe lethargy• Stupor
• >70%• Death
• Congenital• Asymptomatic
Methemoglobinemia• Suspicion
• Clinical cyanosis• Normal arterial pO2• “chocolate brown blood”• Pulse oximetry unreliable
Methemoglobinemia• Diagnosis
• Co-oximetry• Respiratory therapy• False positives with methylene blue with
some methods
• Genetic testing
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
Methemoglobinemia• Treatment
• G6PD deficiency• May not respond to treatment
• Other• Hyperbaric oxygen• Exchange Transfusion
Methemoglobinemia• Lessons
• Always consider in differential diagnosis of cyanosis
• Caution with use of topical anesthetics• History
• Cyanosis• Blue nail beds• Blue lips
• Family History