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Plasma Exchange

Plasma Exchange. Chan King Chung. History. Begins in the 1970s Blood cell separators Initially to treat anti-GBM disease Lowering circulating antibody Widespread use in different condition Some indication replaced by other method Selective extraction for hypercholesterolemia

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Plasma Exchange

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  1. Plasma Exchange Chan King Chung

  2. History • Begins in the 1970s • Blood cell separators • Initially to treat anti-GBM disease • Lowering circulating antibody • Widespread use in different condition • Some indication replaced by other method • Selective extraction for hypercholesterolemia • IVIg for immunotherapy

  3. Indications • Removal of ‘evil’ humoral substances • Antibodies • Goodpasture’s Syndrome (Anti-GBM) • Wegener Granulomatosis (ANCA) • Myasthensia Gravis (Anti-AChR) • Toxins • Triglycerides • Paraproteins • Thyroxin • Acetylsalicylate • Cytokines • Sepsis • Uncertain • Thrombotic Thrombocytopenic Purpura • Haemolytic Uraemic Syndrome • Guillain-Barre´ syndrome • Miller Fisher syndrome • Liver failure

  4. Physiology of Body Fluid

  5. Dosage • Blood volume 7% of BW • Plasma volume ~4% of BW (40mL/kg) • Residual plasma volume = e-(volume removed) • Change of 1 plasma volume = 37% remain

  6. Dosage • Usual 1-1.3x plasma volume per session • Volume = (1- Hct) x 70mL x BW x 1 or 1.3 • ~2 to 3L in most case

  7. Dosage • Frequency of Plasma Exchange depends on • Distribution of substance • Rate of production • ~5 plasma volume in 7 to 10 days will remove ~90% of the plasma substance

  8. Techniques of Plasma Exchange • Access: large vein ± dialysis catheter • Anticoagulation • Cell Separator • Centrifugation • Membrane plasma filtration • Replacement • Fresh frozen plasma • Albumin • Colloid / Crystalloid

  9. Anticoagulation • Heparin • 2000 to 5000 units bolus then • 500 to 2000 units/hour • Citrate

  10. Cell Separator • Centrifugation • 600mL in 37 mins

  11. Cell Separator • Membrane filtration

  12. Performance of Prisma TPE

  13. Replacement • Post-filter • FFP • Contain all component • Replacement of specific factor (TTP / Liver failure) • Risk of transfusion • Citrate Toxicity • ? Giving back the ‘Evil’ humoral

  14. Composition of Plasma • Water • Electrolytes • Na, Cl, Ca, K, PO4, Mg • Osmotic pressure of 5526 mmHg • Between ECF and ICF • Proteins • Albumin, Globulins, Complements, Transport Protein, etc. • Oncotic pressure of 25 mmHg • Distribution between plasma & interstitial fluid

  15. Replacement • Albumin • Expensive • Risk of hypokalemia and hypocalcaemia • Risk of bleeding • Risk of Prion diseases • Mixing electrolyte with 5% albumin solution before use (in paediatrics)

  16. Albumin Replacement e-

  17. Replacement • Colloids • HES / Gelofusin • Cheaper compare with Albumin • Safer • Problem with oncotic pressure • Slowly loosing oncotic pressure -> hypovolaemia • Pulmonary edema • Problem with electrolyte / bleeding

  18. Colloid Replacement H20

  19. Colloid Replacement • Risk of hypovolaemia balanced by • Higher volume of replacement • Close monitoring • Risk of pulmonary edema is low • Normal oncotic pressure is ~25mmHg • Theoretical risk of pulmonary edema when oncotic pressure is <10mmHg

  20. Colloid Replacement • Studies using HES (t1/2: 8hr) instead of albumin had demonstrated the safety of colloid Journal of Clinical Apheresis. 12(3):146-53, 1997 • Less data is available for using gelatin (e.g. gelofusine t1/2: 2hr) • Usually when Albumin > 30g/L

  21. Replacement • Crystalloid • Crystalloid-only replacement is not used • Half crystalloid, half albumin regime is commonly used for saving money • ~1/3 of crystalloid stay in intravascular space • Bolus of crystalloid may be given for hypotension

  22. Typical Replacement • Full volume gelatin • Half gelatin then half albumin • Resulting Alb level 25g/dL • Half gelatin then half FFP • Full volume FFP • For TTP

  23. Electrolyte Replacement • Hypokalemia might occur • 3L plasma only contain 10-15 mmol K • Large reserve inside the cells • Hypocalcaemia • 3L plasma contain 6–7 mmol Ca • ~10ml 10%CaCl2 • Especially if • Total Albumin replacement (Ca++ 0.5-0.75mmol/L) • Cannot clear citrate (as anticoagulation / FFP / Albumin)

  24. Setup • 3L Session (3hr) Anticoagulation (ACDA 240mL/hr) Replacement (1L/hr) Blood (120-150 mL/min) Plasma (1L/hr)

  25. Adverse Reaction • Hypotension • Hypovolaemia • Hypocalcaemia • Allergic reaction • ACEI • Membrane activation • Prekallikrine activator in SPPF

  26. Adverse Reaction • Bleeding tendency • Lowered coagulation factors in underlying bleeding disease (TTP) • Immunosuppression • Lost of immunoglobulins, complements

  27. Modification of Plasma Exchange • Coupled Plasma Filtration Adsorption Plasma Filter Charcoal

  28. How are we going to do ? • By Haematology as much as possible • Prisma TPE • AK10

  29. Prisma TPE • More correct monitoring of volume • Automatically stop removal pump when the replacement is empty • Safer • Unfamiliar • Higher cost

  30. Prisma TPE • Setting • Haematocrit • Blood flow rate • Replacement bottle volume • Replacement volume • Replacement rate • Net patient plasma removal rate • ** Net plasma removal volume **

  31. Prisma TPE • 3L Session (3hr) Anticoagulation (ACDA 240mL/hr) Replacement (1L/hr) Blood (120-150 mL/min) Plasma [1L/hr]+[0mL/hr]

  32. ? Fluid Gain • 240mL/hr for 3 hours • 720mL over 3 hours • A small volume only. Can be handled by kidney • Useful to counter act hypotension • In theory, may set 80mL/hr net loss, as only 1/3 is in intravascular space

  33. AK10 • Cheaper and more familiar • Same setup as CVVH • Only 1 replacement pump and 1 filtrate pump • Volume state less accurate than Prisma • Risk of hypovolaemia if the replacement pump stopped

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