What baseline labs, cardiac imaging, and monitoring protocol should be used before, during, and after administering the standard 2 g/kg intravenous immunoglobulin (IVIG) dose to a child with Kawasaki disease?

IVIG Monitoring Protocol for Kawasaki Disease

Baseline Assessment Before IVIG Administration

Obtain baseline echocardiography with color-flow Doppler at diagnosis to document coronary artery dimensions before initiating the standard 2 g/kg IVIG infusion. 1

Pre-Treatment Laboratory Work

• Measure C-reactive protein (CRP) rather than ESR as your primary inflammatory marker, because IVIG will artificially elevate ESR and render it unreliable for subsequent monitoring 1, 2
• Complete blood count with hemoglobin level (low hemoglobin may predict IVIG resistance) 3
• Baseline inflammatory markers (CRP preferred over ESR) 1

Pre-Treatment Cardiac Imaging

• Perform echocardiography with color-flow Doppler using a low Nyquist limit to visualize flow in the proximal coronary arteries and establish baseline coronary dimensions 2
• Document Z-scores for coronary artery measurements to stratify future anticoagulation needs 1

During IVIG Infusion Protocol

Administer IVIG 2 g/kg as a single infusion over 10-12 hours combined with high-dose aspirin 80-100 mg/kg/day divided into four doses, ideally within the first 10 days of fever onset. 1, 2, 4

Infusion Monitoring

• Monitor vital signs and temperature throughout the 10-12 hour infusion 1
• Watch for immediate hypersensitivity reactions during administration 5
• The 2 g/kg single-dose regimen is superior to lower doses (1 g/kg) or divided dosing, with a U-shaped curve showing optimal outcomes at exactly 2.0 g/kg 6, 5

Post-IVIG Monitoring Protocol

Temperature Surveillance (Critical 36-48 Hour Window)

Monitor temperature closely for 36-48 hours after IVIG completion to detect IVIG resistance, defined as persistent or recrudescent fever ≥36 hours after the infusion ends. 1, 2 This occurs in 10-20% of patients and mandates a second 2 g/kg IVIG dose. 1

Aspirin Management Algorithm

• Continue high-dose aspirin (80-100 mg/kg/day in four divided doses) until the patient is afebrile for 48-72 hours 1, 2, 4
• Then transition to low-dose aspirin 3-5 mg/kg/day as a single daily dose 1, 2
• Continue low-dose aspirin for 6-8 weeks if no coronary abnormalities develop 1, 2

Laboratory Monitoring Post-IVIG

• Use CRP (not ESR) to assess treatment response, as IVIG elevates ESR and makes it unreliable for monitoring inflammation resolution 1, 2
• Resolution of CRP confirms adequate treatment response 2

Echocardiographic Surveillance Schedule

Perform serial echocardiography at three time points: at diagnosis, at 2 weeks, and at 6-8 weeks after treatment initiation. 1, 2 This protocol detects coronary artery abnormalities that develop despite treatment and guides long-term antiplatelet strategy.

Management of IVIG-Resistant Disease

First-Line Rescue Therapy

If fever persists or recurs ≥36 hours after the initial IVIG dose, immediately administer a second dose of IVIG 2 g/kg as a single infusion. 1, 2, 4 This is the highest-level evidence recommendation for IVIG resistance.

Second-Line Options (After Two IVIG Doses)

• Methylprednisolone 20-30 mg/kg IV daily for 3 days 2, 4
• OR Infliximab 5 mg/kg IV as a single infusion over 2 hours 1, 2, 4

Long-Term Anticoagulation Based on Coronary Findings

Risk Stratification Algorithm

• No coronary abnormalities: Discontinue low-dose aspirin at 6-8 weeks 1, 2, 4
• Small aneurysms: Continue low-dose aspirin 3-5 mg/kg/day indefinitely 2, 4
• Moderate aneurysms (Z-score 5-10 or 4-6 mm): Low-dose aspirin 3-5 mg/kg/day plus clopidogrel 1 mg/kg/day (max 75 mg/day) 1, 2
• Giant aneurysms (Z-score ≥10 or ≥8 mm): Low-dose aspirin 3-5 mg/kg/day plus warfarin (target INR 2.0-3.0) 1, 2, 4

Critical Safety Caveats

Immunization Timing

Defer measles, mumps, rubella, and varicella vaccinations for 11 months after high-dose IVIG administration because IVIG interferes with vaccine efficacy through passive antibody transfer. 1, 2, 4

Aspirin-Specific Warnings

• Mandate annual influenza vaccination for all children on long-term aspirin therapy to prevent Reye syndrome during influenza infection 1, 2, 4
• Never co-administer ibuprofen with aspirin, as ibuprofen antagonizes aspirin's irreversible antiplatelet effect 1, 2

High-Risk Populations

Infants <1 year have the highest risk for incomplete presentations and paradoxically the highest rates of coronary aneurysms if untreated, so maintain a low threshold for treatment even with atypical presentations. 1, 2

Late Presentation Exception

Children presenting after day 10 of illness should still receive IVIG if they have ongoing systemic inflammation (CRP >3.0 mg/dL) together with either persistent fever or coronary artery aneurysms. 2