SICKLE  CELL

 

Etiology:

  1. Hgb has Valin substituted by Glutamic acid. When under hypoxic environment, Hgb is reduced and RBC deforms into sickle shape.mmThis in turn clogs the circulation that causes thrombosis, in local O2 supply  with consequent ischemia and infarction (autosplenism), organ deterioration, susceptibility  to infections (Strep. pneumoniae, H.flu, salmonella). Also, in view of hypoximia and acidotic  milieu, RBCs hemolysis (predisposition to GB stone,  in BM erythrocyte line production).
     
  2. Different types of sickle cells depends on zygotic state. These are as follows:
     
    1. a) SC Anemia (Hb SS) - both parents are sicklers.
       
    2. b) SC Trait (Hb AS) - one parent is a sickler. Both Hgb A and Hgb S are seen on electrophoresis.

S & S:

Pts have  S&S of complications that may occur. These are:

  1. Vasocclusive crisis - are 2ry to local thrombosis and microinfarction.  temp,  WBC,  retics. Joints, abdomen, bone and back are common sites.
     
  2. Hemolytic crisis - pts have chronic anemia, but now is exacerbated.  LDH,  bilirubin,  RBCs.
     
  3. Aplastic crisis -2ry to parvovirus infection or  in  folic acid PO intake.
     
  4. Sequestration crisis - RBCs are hostaged by spleen. This results in hemodynamic instability, spleen, pancytopenia; usually in early childhood.
     
  5. Other  S&S are due to infection (pneumonia, osteo), CVA, GB stones, poor healing (skin ulcers), optic neurovascular damage 2ry to microinfarctions, cor  pulmonale 2ry to chronic respiratory hypoxia and consequent vasospasms, renal failure, priapism, hematuria (usually painless. If pain is present in the flank this can indicate papillary necrosis), PE (2ry to thrombosis), joint pathologies (infection, aseptic necrosis).

DX:

  1. Lab tests indicate and lead to one or more of the above entities. Most common ER visit is 2ry to vaso-occlusive crisis and low temp,  retic. count,  WBC  are seen. If also LDH and bili are  we deal with hemolytic crisis. If retic. count is not ed, this suggests aplastic crisis. NOTE!!! Pts have abnormal labs as a baseline, thus labs obtained on admission must be compared with baseline labs.
     
  2. 2. Routine CXray and UA must be done to r/o precipitating factors that worsened pts chronic state. Also the exam must include exam of joints, r/o possibility of Osteo. V/Q, US, CT are ordered if  history or exam are suggestive.

Treatment:

  1. Vaso-occlusive crisis are treated with  O2 , fluids (PO or IV) and generous pain medications. Administration of narcotics  by  you, will neither cause pt to become "drug seeker" nor will it exacerbate already established behavior. Pt's RR and pupil size must be frequently checked and pt should be placed on pulse oximetry if indicated by doses given.
     
  2. Folic acid 1mg  PO.
     
  3. 3. In case of CVA or surgery, exchange transfusion to replace excess of Hgb S, may be indicated.

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