Sickle Cell Anemia

Sickle cell anemia • The defect in β -chain, position 6 → glutamic acid substituted by valine • 3 types of crisis o hemolytic→ further anemia o sickling → pain & vaso-occlusive o Aplastic → may cause death. • Ethnic background: Mediterranean and African-American. • In infancy Hb F is protective. • % of Hb S o trait (mild) o < 50% is Hb S o sickling do not occur under normal physiological conditions o may happen under extreme conditions e.g severe hypoxemia. o Disease (severe) o Hb S > 75% may up to 95% o Could be associated with other abnormal Hb e.g Hb C o Pt with Hb SC have a normal Hb level, but at a greater risk of sickling. • Pre-op you need to knew what is the result of the Hb electrophoresis.

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↑ mortality with ↑ in the number of the painful crisis in adult per-year. O2-Hb curve shifted to the Right, with P50 of 31 mmHg. The sickle cells are more fragile with shorter life span Pt may treated with Hydroxy-urea to ↑ Hb F level, pre-op ↓ peri-op risk with ↑ Hb F level Pre-op Mx: o Traditional approach: o PRBC over several days pre-op→ ↓ erythropiosis→ ↓ retics count → this will ↓ Hb S, and it may fall below 40% o Conservative approach: o Traetment will be given when necessary to ↑ Hb > 10 o It is effective as the traditional, and may avoid risk of transfusion. Anesthesia Consideration: A →OSA→ due to tonsiller hypertrophy B →Acute chest syndrome  Lung infarction and fibrosis→ Cor-pulmonal  Pneumonia C→ MI, RV & LV dysfunction → CHF

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GI-Hepatic→ mesenteric ischemia, gall stone, Aotu-splenectomy → risk of infection ( pneumococcal vaccine) Renal →CRF due to multi-infarction. Obstetrics→↑ risk of pre-term labor,↑ perinatal mortality,↑ risk of placenta previa and abruption placenta. CNS→stroke, seizure , and intracranial hemorrhage MSK → ulcers and myonecrosis→ risk of ischemia with position Metabolism→↓ cholinesterase level Crisis ↑ by o Dehydration. o Hypoxia o Acidosis o Hypothermia and fever. What to do? o ↑ FiO2 o hydrate well o monitor acid-base status o maintain normothermia

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tourniquet ?? o if yes→ exsanguinate the limb well and minimize the tourniquet time. Anticipated problems: o Crisis→ hemolytic, ischemic o transfusion reaction→ hemolytic, due to multi-Tx → allu-immunization.