Plasma Exchange in Pediatric Autoimmune Encephalitis

This will be a Prospective, randomized, open- label, parallel-group, center trial, which will include enough number of children admitted at Pediatric Intensive Care Unit (PICU) of Menoufia university Hospital with autoimmune encephalitis from August 2026 to February 2027.

Grouping :

The study population will be divided into two groups:

• Daily PLEX Group (Arm A):

This group will perform PLEX on consecutive days (e.g., Day 1, 2, 3, 4, 5) for 5 sessions; up to 7 sessions allowed.

• Alternate-Day PLEX Group (Arm B):

This group will perform PLEX every other day (e.g., Day 1, 3, 5, 7, 9) for 5 sessions; up to 7 sessions allowed.

All patients in this study will be subjected to:

A- Demographic and clinical data Collection:

• Patient demographics: age, sex, Wt., Ht., and body mass index (BMI).
• PLEX parameters: date/time of each session, exchanged volume, replacement fluid, anticoagulation used and immediate complications if any.

B- Full clinical examination will be done including vital signs (HR, RR, BP, temperature), Pediatric Glasgow Coma Scale to assess consciousness level and neurological examination.

C- Investigations will be done including the following:

Laboratory Analysis: CBC, CRP, Electrolytes, calcium level, blood culture, urea, creatinine, ALT, AST, procalcitonin, coagulation profile and D-dimer level.

Radiological: Chest X ray, Brain CT, MRI and EEG if they needed. Intervention and Monitoring

Plasma Exchange Procedure (both arms):

A- Access: Central venous catheter (size appropriate for age and weight) or existing dialysis catheter.

B- Exchange volume: 1-1.5 plasma volumes per session (age/weight-adjusted - typical formula: plasma volume = 0.07 × weight in kg × (1 - hematocrit)).

C- Replacement fluid: 5% human albumin as first choice; fresh frozen plasma (FFP) may be used if clinically indicated (bleeding, coagulopathy), or combination as per local protocol.

D- Anticoagulation: Regional citrate anticoagulation or systemic heparin according to institutional practice; monitor ionized calcium if citrate used.

E- Monitoring: Vital signs pre-, intra-, and post-procedure; electrolytes, coagulation profile and calcium level as clinically indicated.

F- Number of sessions: Up to 5 sessions recommended; clinicians may extend to 7 sessions if inadequate clinical response.

Inclusion criteria

• Childern diagnosed as autoimmune encephalitis according to Cellucci et al., 2020; acute/subacute onset (<3 months) of encephalopathy with at least one of: new focal CNS findings, seizures, CSF pleocytosis, MRI suggestive of encephalitis, and supportive antibody testing when available.
• Autoimmune encephalitis cases indicated clinically for PLEX as determined by the treating team (e.g., severe disease, refractory to steroids/IVIG or as part of first-line combination therapy).

Exclusion criteria

• Hemodynamic instability not amenable to plasma exchange.
• Severe coagulopathy uncorrectable prior to PLEX (INR >2 despite correction, platelets <50,000/µL unless corrected).
• Contraindications to central venous access placement.
• Enrollment in another interventional trial that would interfere with the outcomes.