Conducting an oral challenge

Question 1

Indications for an OFC

Answer 1

1. sIgE and SPT results are not consistent with history
2. Expanding the diet where there are multiple restrictions
3. Assessing the status of tolerance in cross reactive foods
4. Assessing the effect of food processing on food tolerability
5. When the family and physician agree that the risk estimated from the medical history and the test results is outweighed by the benefit of possibly adding a food to the diet

Question 2

Reasons to delay or reschedule an OFC

Answer 2

1. Concurrent illness
2. Used a short acting B agonist within 48 hours for cough or wheeze
3. Poorly controlled asthma, AD, or AR
4. Pregnant
5. BB therapy
6. Unstable CV disease
7. Patient has not d/c’d meds required for OFC

Question 3

Medications that may affect the OFC

Answer 3

1. Antihistamines
2. 2nd gen H1 blockers
3. Nasal antihistamines
4. atypical antidepressants/sedatives
5. Benzos
6. TCAs
7. ACEi
8. NSAIDs
9. PPIs

• PRACTALL guidelines recommend discontinuation of anti histamines 5 half lives before the OFC

Question 4

Factors reported with fatal or near fatal food induced reactions

Answer 4

1. Peanut, tree nut, fish, shellfish, milk
2. Asthma
3. delayed use of Epi
4. Upright posture during anaphylactic reaction may contribute to cardiovascular compromise

Question 5

ACEi’s and OFCs

Answer 5

ACEi may enhance or induce allergic reactions and d/c before the OFC may be considered if an equally effective alt. is available

Question 6

Omalizumab and OFCs

Answer 6

Omalizumab may decrease skin test reactivity and increase allergen specific IgE levels checked before an OFC.

It may also increase the threshold dose for reaction, and is therefore not reflective of the reaction that may happen if Omalizumb is not being used

Question 7

H2 blockers and OFCs

Answer 7

may increase severity of reactions by decreasing the digestion of food proteins

Question 8

Pre OFC considerations for the parent

Answer 8

1. Recommended that the patient refrain from eating at least 4 hours before the challenge bc fasting enhances the absorption of the challenge food
2. Parents should be advised of the long process and plan to keep the child entertained
3. If possible other kids should not be brought

Question 9

Pre OFC prep for the MD

Answer 9

1. Monitored setting with experience in recognition and mgmt of anaphylaxis
2. medications that interfere with interpretation of the OFC should be discontinued
3. VS obtained and focused examination
4. Medications ready based on weight
5. Equipment available and ready

Question 10

Dose required in OFC to avoid false negatives is?

Answer 10

2000 mg
Recommended final dose is 3000 mg of food protein

Question 11

How much protein in in 1 large egg?

Answer 11

6 grams

Question 12

How much protein is in infant formula?

Answer 12

5 oz = 2-3 grams

Question 13

Protein content in peanuts

Answer 13

8 peanuts = 2 grams

Question 14

Protein content in PB

Answer 14

1 tbsp = 3 grams

Question 15

Protein content in almonds

Answer 15

11 whole nuts = 3 grams

Question 16

Protein content of cashew

Answer 16

10 whole nuts = 3 grams

Question 17

Protein content in hazelnut

Answer 17

3 tbsp hazelnut or hazelnut meal = 3 grams

Question 18

Protein content in pistachio

Answer 18

20 whole nuts = 3 grams