Plasma Exchange

General technique of extracorporeal blood filtration or centrifugation to separate cellular or plasma components. Can be divided into:

Indications

Cellular:

Indications are divided by the American Society for Apheresis into three categories based on the evidence supporting plasmapheresis in that condition:

  • Category I
    Accepted as first line therapy, and indicated in bold.
  • Category II
    Second-line therapy.
  • Category III
    Not established.
  • Category IV
    Ineffective or harmful.
  • Leukocytosis
    AML.
  • Sickle cell crisis

In general, for a substance to be effectively removed by apheresis it must be:

  • Present intravascularly
  • Unable to be removed by more simple means (RRT)
    Usually due to molecular weight or plasma protein binding.
  • Have a long enough half-life
    Otherwise, just wait?
  • Not be rapidly replenished
  • Not have a more simple treatment available

Proteins:

Hyperviscosity syndrome describes impaired blood flow and organ perfusion due to ↑ blood viscosity, which occurs due to ↑ concentration of cells or macromolecules, and is characterised by:

  • Hypervolaemia
  • Visual disturbances
  • Neurological dysfunction
    Coma, seizures.
  • Autoantibodies
    • Myasthenia gravis
    • Goodpasture Syndrome
    • GBS
      Equivalent to IVIG.
    • Chronic Inflammatory Demyelinating Polyradiculoneuropathy
    • Granulomatosis with Polyangiitis
      The disease formally known as Wegener’s granulomatosis.
  • Immunoglobulins
    May cause hyperviscosity syndrome, coagulopathy, or renal failure. Immunoglobulin-producing diseases include:
    • Monoclonal gammopathy
    • Waldenstrom macroglobulinaemia
  • Immune complexes
    • Cryoglobulinaemia
      Acute fulminant vasculitis, renal failure, or neurological impairment.
    • Rapidly progressive glomerulonephritis
    • SLE
      For AKI, cerebritis, or acute fulminant lupus pneumonitis.
  • Other immune-mediated disease
    • Renal transplant rejection
    • Thrombotic microangiopathies
      • TTP
      • HUS
      • DIC
      • Catastrophic APS
  • Protein-bound substances
    • Toxins
      • Heavy metals
        • Mercury
        • Cisplatin
      • Herbal preparations
        • Kava
      • Digoxin
      • Paraquat
        Relatively ineffective.
    • Thyroid storm

Efficacy of plasma exchange for toxins is generally over-rated due to the relatively small volume of distribution of the intravascular compartment.

Plasma Solids:

  • Triglycerides
    Indicated, with very weak evidence, for pancreatitis secondary to hypertriglycerideaemia (>1g/dL).

Contraindications

Equipment

  • Vascular access device
  • Plasmapheresis machine
    • Semi-permeable membrane filter
      30× more porous than the conventional dialysis filter.
    • Regional anticoagulation
  • Replacement fluid

Technique

  • Withhold ACE inhibitors and A2RBs
    ↓ Bradykinin activation, which may lead to hypotension and respiratory distress during exchange.
  • Placement of a vascular access catheter
    • Dual-lumen dialysis catheter is generally used
    • Single-lumen cannula can be used
      • Blood periodically removed, filtered, and returned
      • ↓ Efficiency compared to dual-lumen configuration
  • Removal of 1-1.5x plasma volume
    Single exchange of 40mL/kg can remove ~50% of plasma factors (including clotting factors) if not replaced, with replenishment in 24-48 hours.
  • Repeated daily or second-daily

Administration of essential medications should be timed around plasma exchange, as these may also be removed.

Complications

  • Procedural
    • Vascular injury
  • Pump
    • Hypocalcaemia
      Citrate mediated.
    • Haemolysis
    • Air embolism
    • Haemodynamic instability
    • Hypothermia
      • Cooling, as occurs in any extracorporeal circuit
      • Cold replacement fluid
  • Replacement fluid effects
    • Transfusion reactions
      TRALI is the major cause of plasma exchange related mortality.
    • Removal of other substances
      e.g. Loss of therapeutic drugs.
    • Anaemia
    • Coagulopathy
      Dilutional, particularly if albumin is used as replacement fluid. Consider plasma as the replacement fluid if the patient is at ↑ bleeding risk.
    • Sepsis

References

  1. Russi G, Marson P. Urgent plasma exchange: how, where and when. Blood Transfus. 2011 Oct;9(4):356-61. doi: 10.2450/2011.0093-10. Epub 2011 Jul 18.
  2. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.