Timing of TPE Before Thymectomy in Myasthenia Gravis
Total Plasma Exchange (TPE) should be performed 10-30 days before thymectomy, consisting of 5 sessions conducted every other day, with each session exchanging 200-250 mL plasma/kg body weight or 1-L exchanges using fresh-frozen plasma or 5% albumin. 1
Preoperative Optimization Protocol
Medical Control Must Be Achieved First
Medical control of myasthenia gravis is mandatory before any surgical procedure, including thymectomy 1, 2. This is critical because approximately 20% of thymoma-related mortality is directly attributable to myasthenia gravis complications rather than the tumor itself 2.
TPE Protocol Specifications
The standard TPE protocol involves:
- 5 sessions total, performed every other day 1
- Volume: 200-250 mL plasma/kg body weight or 1-L exchanges per session 1
- Replacement fluid: Fresh-frozen plasma or 5% albumin, exchanging twice the blood volume 1
- Timing window: 10-30 days before the scheduled surgery 1
Alternative: IVIG May Be Preferred
IVIG is increasingly favored over TPE as first-line preoperative therapy due to easier administration, wider availability, and fewer complications 1. The IVIG protocol consists of 0.4 g/kg/day for 5 consecutive days (total dose 2 g/kg) 1.
Patient Selection for Preoperative TPE/IVIG
High-Risk Patients Requiring Preoperative Treatment
Patients with the following features should receive preoperative IVIG or TPE 1:
- Dysphagia 1
- Notable weight loss 1
- Severe generalized weakness 1
- Respiratory compromise (vital capacity <20 mL/kg, maximum inspiratory pressure <30 cm H2O, or maximum expiratory pressure <40 cm H2O) 1
Mandatory Preoperative Assessment
Before thymectomy, all patients must undergo 1, 3:
- Comprehensive respiratory assessment with negative inspiratory force (NIF) and vital capacity (VC) measurements 1
- Serum anti-acetylcholine receptor antibody levels 1, 2
- Cardiac evaluation with ECG and echocardiogram if respiratory failure or elevated CPK levels present 1
- Neurologist consultation and treatment optimization 2
Critical Pitfalls to Avoid
IgA Deficiency Screening
Check serum IgA levels before administering IVIG, as IgA deficiency may lead to severe anaphylaxis 1. This is a potentially fatal complication that is entirely preventable with proper screening.
Timing Considerations
The 10-30 day window allows sufficient time for:
- Clinical improvement to manifest 1
- Antibody levels to decrease (though clinical benefit does not require antibody reduction) 4
- Optimization of respiratory function before anesthesia 3
Perioperative Medication Management
Continue anticholinesterase medications (pyridostigmine) perioperatively unless contraindicated 1. However, patients on immunosuppression therapy are more prone to complications 5, so careful monitoring is essential.
Postoperative Monitoring
Close monitoring for myasthenic crisis is essential postoperatively, including respiratory failure surveillance 1. Consider early tracheostomy in high-risk patients, particularly those unable to lift arms from bed at 1 week after intubation 1.