-group of inherited autosomal recessive disorders characterized by an abnormal form of hemoglobin in the RBC-usually identified in childhood
-Hemoglobin S causes the erythrocyte to stiffen and elongate, taking on a sickle shape
-Sickle Cell traint occurs when a person is heterozygous for emoglobin S, the person has inherited hemogloin S from one parent and normal hgb A from other parent.
-Sickling episodes: triggered by low oxygen tension in blood. Hypoxia or deoxygenation of RCs can be caused y viral or bacterial infection, high altitiude, emotional or physical stress, surgery and blood loss-Infection is most common cause of hypoxia
-Dyhydration, increased hydrogen ion (acidosis), increased plasma osmalility, decreased plasma volume, and low body temp can cause or sustain sicklling episodes
=> Vasoocclusive Crisis:
- -Sickling causes occlusion--> acute or chronic tissue injusy and results in hemostasis (self perpetuating cycle of local hypoxia and more sickle)-sickle cells hemolyzed by spleen.
- -Vasoocclusive phenomena and hyemolysis are the clinical hallmarks of SCD
Sickled cells impairs blood flow causing vasospasm, further restricting blood flow. Severe capillary hypxoia causes changes in membrane permeability, leading to plasma loss, hemoconcentration, thrombi and further circulatory stagnation. Tissue ischemia, infarctionand necrosis eventually occur from Oxygen lack.
-SHOCK is possicble, life threatening consequenc of sickle cell crisis
Pain is primary. Anemic but asymptomatic exccept during sickling episodes. Jaundice is common (from hemolysis) and pats prone to gallstones (cholelithiasis)
- =>Infection is a MAJOR commplication, cause of morbidity and mortality in patients.
- -Spleen fialure to phagocytize foreign substance as it becomes infracted and dysfunctiional), spleen becomes SMALL due to repeated scarring (autosplenctomy)
- -Pneumonia is most common infection; can cause aplasstic and hemolytic crissis and gallstones
- -Acute Chest sydnrom: describes acute pulmonary complication, tissue fnfarction and fat embolism
- -Pulmonary infarction: cause pulm htn, MI, HF, COR PULMONALE.
- -Heart may become ischemia and enlarged--> HF-Injured kidenys from increased Blood viscosisty and lack of Oxygen.
- -Priapism: persistent erection due to vein occllusion in penis.
- => Collaborative Care:
- 1. Alleviate symtoms
- 2. Minmize end-organ damage
- 3. Teach: avoid high altitudes, dddrink fluids, teat infections, immunizations
- => Treatments:
- -Hydroxyurea: chemo drug;; increases production of fetal hemoglboin, decreases reactive nutrophil count and increases RBBC volume.
- -Hematopoietic stem cell transplation is the ONLY aviaialbe treatment that cute some pts