| Protocol |
- Basic requirements – Clinician supervision, secure IV access, immediate availability of fluid resuscitation.
- Baseline vital signs and complete blood count with differential to determine the baseline peripheral blood neutrophil count.
- Administration of food protein 0.03 to 0.6 g/kg body weight in 3 equal doses over 45 minutes generally not to exceed total 3 g protein or 10 g of total food (100 mL of liquid) for an initial feeding. A lower dose is used in patients with a history of severe reactions.
- Observe patients for at least 4 hours from the beginning of the OFC.
- Very-low-dose initial feeding – If no reaction occurs within 2 to 3 hours of administration of the final dose, feed the patient an age-appropriate serving of the food followed by 4 hours of observation.
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| Criteria for a positive challenge |
Major criterion: - Vomiting in the 1- to 4-hour period after ingestion of the suspect food and the absence of classic IgE-mediated allergic skin or respiratory symptoms.
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Minor criteria: - Lethargy.
- Pallor.
- Diarrhea in 5 to 10 hours after food ingestion.
- Hypotension.
- Hypothermia.
- Increased neutrophil count of at least 1500 neutrophils above the baseline count*.
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| Interpretation of the food challenge outcome |
The OFC is considered diagnostic of FPIES (ie, positive) if the major criterion is met with at least 2 minor criteria. However, we suggest 2 important caveats to these criteria: - With the rapid use of ondansetron, many of the minor criteria, such as repetitive vomiting, pallor and lethargy, may be averted.
- Not all facilities performing challenges have the ability to perform neutrophil counts in a timely manner. Therefore, the treating clinician may decide that a challenge is diagnostic in some instances even if only the major criterion was met.
However, in challenges performed for research purposes, adherence to stringent criteria for challenge positivity is the standard. |
| Treatment for a positive challenge¶ |
- First-line therapy – Fluid resuscitation with 20 mL/kg IV boluses of normal saline (0.9% sodium chloride).
- Antiemetic – Ondansetron 0.15 mg/kg IV, maximum single dose 16 mg. Ondansetron may also be used IM; maximum dose suitable for IM administration is 4 mg for ages 12 years and older and 2 mg for younger ages due to the large volume of the injection.
- Additional therapy for severe reactions – Glucocorticoid (eg, methylprednisolone 1 mg/kg IV, maximum single dose 80 mg).
- Therapy for severe hypotension/shock – IM epinephrine:
- Either:
- 1 mg/mL ampule:
- 0.01 mg/kg per dose; maximum single dose 0.3 mL (0.3 mg) for a child <13 years and 0.5 mL (0.5 mg) if ≥13 years.
- OR
- Auto-injector:
- <10 kg – 0.1 mg (infant autoinjector).
- 10 to 25 kg – 0.15 mg IM (pediatric auto-injector).
- >25 kg – 0.3 mg IM.
- May repeat IM epinephrine after 5 to 15 minutes if needed.
- IM epinephrine should not be used as a first-line for managing acute FPIES reactions without fluid replacement and antiemetic therapy.
- In severe shock, IV vasopressors may be needed.
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