What is the procedure for plasmapheresis in critical care, including volume calculation and replacement fluid selection?

Plasmapheresis Procedure in Critical Care

Plasmapheresis in critical care involves removing 60 ml/kg of plasma volume with replacement using albumin or fresh frozen plasma, typically requiring 5-10 treatments administered daily or on alternate days depending on the clinical indication and patient response. 1

Procedure Components

Vascular Access

• Central venous catheter placement (preferably large-bore double-lumen)
• Common sites: internal jugular or femoral veins
• Peripheral access may be used if blood flow rates are adequate

Volume Calculation

• Standard volume: 60 ml/kg of patient's weight 1
• For a 70 kg patient: approximately 4.2 liters of plasma to be exchanged
• Formula: Patient weight (kg) × 60 ml = Total exchange volume

Replacement Fluid Selection

The choice of replacement fluid depends on the clinical indication:

1. 5% Albumin Solution

   • Primary replacement fluid for most indications
   • Used for autoimmune disorders, hyperviscosity syndromes
   • Advantages: Lower risk of allergic reactions and infections

2. Fresh Frozen Plasma (FFP)

   • Indicated for conditions requiring replacement of clotting factors:
     • Thrombotic thrombocytopenic purpura (TTP)
     • Diffuse alveolar hemorrhage
     • ANCA-associated vasculitis with pulmonary hemorrhage 1, 2
   • Also used when removing antibodies that deplete essential plasma components

3. Combination Approach

   • Often uses 20% albumin solution with 0.9% NaCl 3
   • May use part albumin and part FFP based on clinical needs

Treatment Schedule and Duration

• Frequency: Daily treatments for acute conditions until clinical improvement, then every other day 1
• Number of treatments:
  • Typically 5-10 total procedures 2
  • For vasculitis with pulmonary hemorrhage: 7 treatments over 14 days 1
  • Daily until bleeding stops, then every other day
• Session duration: 2-4 hours per session

Monitoring During Procedure

• Continuous vital signs monitoring
• Attention to:
  • Blood pressure (hypotension is common - 8.4% of procedures) 4
  • Heart rate and rhythm (arrhythmias occur in 3.5% of cases) 4
  • Temperature
  • Calcium levels (to prevent hypocalcemia)
  • Potassium levels (to prevent hypokalemia)

Specific Clinical Applications

1. ANCA-Associated Vasculitis

   • Recommended for patients with rapidly increasing serum creatinine 1
   • Indicated for diffuse pulmonary hemorrhage 1
   • Volume: 60 ml/kg replacement
   • Schedule: 7 treatments over 14 days for pulmonary hemorrhage

2. Neurological Disorders

   • Indicated for Guillain-Barré syndrome, myasthenia gravis
   • Typically requires 4-5 exchanges to remove 90% of harmful antibodies 5

3. Hyperviscosity Syndromes

   • First-line treatment for cryoglobulinemic hyperviscosity 1
   • Used in multiple myeloma and Waldenström's macroglobulinemia 3

Complications and Management

• Common mild complications (generally transient):

  • Hypotension (8.4% of procedures) 4
  • Arrhythmias (3.5%) 4
  • Paresthesias (1.1%) 4
  • Sensation of cold with elevated temperature (1.1%) 4

• Severe complications (rare - 2.16% of procedures) 4:

  • Shock
  • Severe hypotension requiring vasopressors
  • Persistent arrhythmias
  • Hemolysis

• Management strategies:

  • Pre-procedure assessment of fluid status
  • Calcium supplementation during procedure
  • Careful anticoagulation monitoring
  • Warming of replacement fluids

Combination with Other Therapies

• Plasmapheresis should be combined with immunosuppressive medications for optimal results 2
• Common combinations:
  • High-dose corticosteroids
  • Cyclophosphamide
  • Rituximab (for B-cell mediated disorders)

Important Considerations

• Plasmapheresis is most effective when initiated early in disease course 2
• Most beneficial in antibody-mediated conditions rather than T-cell mediated disorders 2
• Not recommended as monotherapy for any condition 2
• Careful monitoring of liver function and viral load is essential in patients with hepatitis 1

Pitfalls to Avoid

• Relying solely on plasmapheresis without concurrent immunosuppression
• Inadequate volume calculation leading to insufficient antibody removal
• Inappropriate replacement fluid selection for specific conditions
• Failure to monitor and replace electrolytes, especially calcium and potassium
• Overlooking potential complications in critically ill patients