What is the recommended post‑IVIG management for a child with acute Kawasaki disease who has just completed a 2 g/kg intravenous immunoglobulin (IVIG) infusion?

Post-IVIG Management for Kawasaki Disease

After completing a 2 g/kg IVIG infusion, continue high-dose aspirin (80-100 mg/kg/day divided into four doses) until the child has been afebrile for 48-72 hours, then transition to low-dose aspirin (3-5 mg/kg/day once daily) and continue until 6-8 weeks after disease onset if no coronary abnormalities develop. 1, 2, 3

Immediate Post-IVIG Aspirin Management

High-Dose Phase

• Continue high-dose aspirin at 80-100 mg/kg/day divided into four doses until the patient has been afebrile for at least 48-72 hours 1, 2, 4, 3
• Monitor for fever resolution, which typically occurs within 24-48 hours after IVIG completion in responsive patients 2, 3

Transition to Low-Dose

• Once afebrile for 48-72 hours, reduce aspirin to 3-5 mg/kg/day as a single daily dose for antiplatelet effect 1, 2, 4, 3
• Continue this low-dose regimen until 6-8 weeks after disease onset if echocardiography shows no coronary abnormalities 1, 2, 4, 3

Monitoring for IVIG Resistance

Definition and Recognition

• IVIG resistance is defined as persistent or recrudescent fever ≥36 hours after completing the initial IVIG infusion, occurring in 10-20% of patients 2, 4, 3, 5
• This is a critical risk factor for developing coronary artery abnormalities 5, 6

Management of IVIG-Resistant Disease

• Administer a second dose of IVIG 2 g/kg as a single infusion as first-line treatment for IVIG resistance 1, 2, 4, 3
• If fever persists after the second IVIG dose, consider methylprednisolone 20-30 mg/kg IV for 3 days or infliximab 5 mg/kg IV as a single infusion 2, 4, 3

Cardiac Monitoring Protocol

Echocardiography Schedule

• Perform echocardiography at diagnosis, 2 weeks, and 6-8 weeks after treatment initiation 3
• More frequent monitoring is required during the first 3 months for patients who develop coronary abnormalities, as this represents the highest risk period for thrombosis 2, 4

Laboratory Monitoring

• Use CRP rather than ESR for monitoring inflammation after IVIG therapy, as IVIG artificially elevates ESR 3
• Check for resolution of inflammatory markers to confirm treatment response 1

Long-Term Antiplatelet Management Based on Coronary Status

No Coronary Abnormalities

• Discontinue low-dose aspirin at 6-8 weeks after disease onset if echocardiography remains normal 1, 2, 4, 3

Small Coronary Aneurysms

• Continue low-dose aspirin 3-5 mg/kg/day indefinitely 1, 4, 3

Moderate Aneurysms (4-6 mm)

• Low-dose aspirin 3-5 mg/kg/day plus clopidogrel 1 mg/kg/day (maximum 75 mg/day) 4, 3

Giant Aneurysms (≥8 mm)

• Low-dose aspirin 3-5 mg/kg/day plus warfarin with target INR 2.0-3.0 2, 4, 3
• Alternatively, use aspirin plus therapeutic doses of low-molecular-weight heparin if warfarin is difficult to regulate 2, 4

Critical Safety Considerations

Immunization Deferrals

• Defer measles, mumps, rubella, and varicella immunizations for 11 months after high-dose IVIG administration due to interference with vaccine efficacy 1, 2, 4, 3
• Children at high risk for measles exposure may be vaccinated earlier and re-immunized 11 months after IVIG if serological response is inadequate 1

Influenza Vaccination

• Administer annual influenza vaccination to all children on long-term aspirin therapy to reduce Reye syndrome risk during influenza infection 1, 2, 4, 3

Drug Interactions

• Never use ibuprofen in children taking aspirin for antiplatelet effects, as it antagonizes the irreversible platelet inhibition induced by aspirin 1, 3

Reye Syndrome Risk

• Instruct parents to contact their physician immediately if the child develops symptoms of or is exposed to influenza or varicella while on aspirin therapy 1
• Some physicians substitute another antiplatelet medication for aspirin during the 6-week period after varicella vaccination 1

Common Pitfalls to Avoid

• Do not prematurely discontinue high-dose aspirin before the child has been afebrile for 48-72 hours, as this may indicate incomplete response 2, 3
• Do not delay second IVIG dose if fever persists or recurs ≥36 hours after initial infusion, as IVIG resistance increases coronary artery abnormality risk 2, 4, 3, 5
• Do not rely solely on ESR for post-IVIG inflammatory monitoring, as IVIG artificially elevates ESR; use CRP instead 3
• Infants under 1 year require heightened vigilance, as they have the highest rates of incomplete presentations and paradoxically the highest risk of coronary aneurysms if inadequately treated 4, 3