What are the guidelines for determining whether to use low volume or high volume plasma exchange in patients with conditions such as myasthenia gravis or Guillain-Barré syndrome?

Plasma Exchange Volume Guidelines

For conditions like myasthenia gravis and Guillain-Barré syndrome, use standard volume plasma exchange (1.0-1.5 plasma volumes per session, calculated at 40 mL/kg body weight), not "low volume" or "high volume" regimens—the distinction is in the number of sessions and frequency, not the volume exchanged per session. 1

Standard Volume Parameters Across All Indications

The term "low volume" versus "high volume" plasma exchange is not used in current clinical practice guidelines. Instead, all plasma exchange protocols use a standardized volume approach:

• Exchange 1.0-1.5 plasma volumes per session (approximately 40 mL/kg body weight) 1
• Each session processes this calculated volume over 2-3 hours 1
• Use 5% albumin as replacement fluid for most indications to minimize transfusion reactions 1

Disease-Specific Session Protocols

Guillain-Barré Syndrome

For patients unable to walk unaided, perform 4-6 plasma exchange sessions (not varying the volume per session): 2, 3

• 4 sessions are effective for severe GBS requiring ventilation 3
• 6 sessions provide no additional benefit over 4 sessions 3
• Initiate within 2 weeks of symptom onset (optimal window is within 7 days, though beneficial up to 30 days) 2
• Schedule sessions on alternate days or every other day 1

Respiratory compromise indicators requiring immediate treatment:

• Vital capacity <20 mL/kg 2, 3
• Maximum inspiratory pressure <30 cmH₂O 2, 3
• Maximum expiratory pressure <40 cmH₂O 2, 3
• Single breath count ≤19 3

Myasthenia Gravis Crisis

Use the same standard volume (1.0-1.5 plasma volumes per session) with 5-7 sessions total: 4, 5

• Plasma exchange shows superior ventilatory status at 2 weeks compared to IVIg (partial F = 6.2, p = 0.02) 5
• Superior functional outcome at 1 month (partial F = 4.5, p = 0.04) 5
• However, complication rate is higher with plasma exchange versus IVIg (13 versus 5 episodes, p = 0.07) 5

ANCA-Associated Vasculitis (for comparison)

7 plasma exchange sessions over 14 days using the same 1.0-1.5 plasma volume per session: 1

• Reserved for severe kidney disease with serum creatinine >5.7 mg/dL (>500 μmol/L) requiring dialysis 1
• Combine with reduced-dose glucocorticoid regimen to minimize infection risk 1

Critical Technical Requirements

Vascular access and monitoring apply uniformly regardless of indication:

• Central venous catheter required for adequate blood flow rates 1
• Continuous blood pressure and heart rate monitoring throughout each session 1
• Ensure adequate volume status before initiating to prevent hypotension 1

Common Pitfalls to Avoid

Do not attempt to modify the volume exchanged per session based on disease severity—instead, adjust the total number of sessions. 1

Do not delay plasma exchange beyond 4-6 weeks of symptom onset in acute inflammatory conditions, as efficacy diminishes with time. 1

For GBS, do not combine plasma exchange with IVIg, as combination therapy is no more effective than either treatment alone. 2

Do not substitute fresh frozen plasma for albumin except in thrombotic microangiopathies or active bleeding. 1