26. Plasmapheresis

Question 1

What is apheresis?

Answer 1

Technology where the blood of a patient is passed through an apparatus that separates out one particular constituent and returns the rest to the circulation. The separated component can be returned after an extracorporal treatment of can be replaced.

Question 2

What are the types of apheresis?

Answer 2

Donation:

• Blood taken from healthy donor can be separated into its componets during blood donations
• The needed component is collected and given to patient and the rest of the blood is given back to the donor
• Includes:
  
  • Plasmapheresis (collection of FFP (Fresh frozen plasma))
  • Erythrocytapheresis
  • Plateletpheresis
  • Leukocytapheresis

Therapy:

• Various techniques may be used when a certain constituent is causing severe symptoms of a disease
• Invasive procedure and therefore only employed if other means to control the disease have failed, or the symptoms are so severe that there is not time to wait for medication to do its effect as it may cause suffering and complications.
• Includes:
  
  • Plasma exchange (removal of harmful substances like toxins or autoantibodies from plasma)
  • LDL apheresis (in familial hypercholesterolemia)
  • Leukocytapheresis (leukemia)
  • Thrombocytapheresis (essential thrombocytopenia, polycythemia vera)
  • Extracorporal photopheresis (treatment of GVHD)
  • …

Question 3

What is therapeutic plasma exchange (TPE) used for?

Answer 3

• Autoantibodies:
  
  • c-ANCA, p-ANCA, anti-GBM, anti-AChR
• Toxins
• Cytokines (SIRS)
• Immune complexes (cryoglobulinemia)
• Lipids (LDL)
• Paraproteins (MM)

Question 4

What are the mechanisms of TPE?

Answer 4

• 2 methods:
  
  • Separation of cellular components from plasma based on:
    
    • Size
    • Density (centrifucation, predominant method)
• Takes 1.5-2h and normally 40-60 ml/Kg of plasma are removed
• The anticoagulation solution ACD-A (citrate dextrose solution A) is used to minimize the effect of the procedure on hemostasis
  
  • It also binds Ca²⁺, which needs to be substituted

Question 5

What are the effects of TPE?

Answer 5

• 60-75% of the macromolecules in the blood are removed
• 90% of the Ig can be removed in 5 consecutive TPEs
• Complement, enzymes and clotting factors are restituted within 24-48h

Question 6

What are the prerequisites of TPE?

Answer 6

Lab:

• Normal ion concentrations in the blood
• Ht > 20%
• Hb > 80 g/l
• PLT = 20 G/l

Parameters:

• BP: 90-160/70-100
• Pulse: 60-140 BPM
• Vascular access

Question 7

What are the complications of TPE?

Answer 7

• Paresthesia (hypocalcemia due to ACD-A)
• Hypotension (hypovolemia)
• Nausea, vomiting
• Urticaria and anaphylaxis (FFP)
• Bleeding/hematoma

Question 8

What are the indications of TPE?

Answer 8

• Class I - Life-threatening conditions:
  
  • ANCA-associated RPGN
  • Goodpasture’s syndrome
  • FSGS (recurrent in transplanted kidney)
  • Waldenström macroglobulinemia
  • TTP
  • APS (autoimmune polyglandular syndrome)
  • Cryoglobulinemia
  • Myasthenia gravis