Sickle Cell Disease
Sickle cell disease is hemoglobinopathy with autosomal dominant inheritance. Beta chain of Hgb-A has Valine substituted for glutamine at position 6.
In the homozygote, deoxygenated Hgb-S becomes insoluble leading to red cells becoming rigid and sickle shaped.
More likely in hypoxia, acidosis, low temperature or cellular dehydration.
Sickling is initially reversible, but when potassium and water is lost, it becomes irreversible.
Local infarction causes
Cerebral vascular events (TIAs and CVAs)
Prevention of sickling
Pre-existing organ damage
Surgical procedure (sickle related)
Patients at risk should have Hgb-S test (sickledex)
However this does not quantify the amount of Hgb-S so if positive sickledex then further testing is needed
Hgb-A >40% with total Hgb >10g/dl but <12 should be achieved by exchange transfusion
Assess for pre-existing organ damage
Avoid sedation (I.e. pre-med- no hypoventilation)
Seek hematological opinion
Pre-oxygenation, hyperventilation can shift oxy-Hgb curve to the left and O2 is more readily bound
May need antibiotics
Step down unit (high dependency unit) care given to maintain good hydration and oxygenation