assessment of the allergic child robin j green phd dept paediatrics, university pretoria
TRANSCRIPT
Assessment of the Allergic Child
Robin J Green
PhD Dept Paediatrics, University Pretoria
The Hypersensitivity Reactions
• Type I: Immediate
• Type II: Cytotoxic
• Type III: Immune complex
• Type IV: Delayed
Gell & Coombs
Atopy
• ‘Inherited tendency to produce increased amounts of IgE in response to small quantities of allergen, and to produce a clinical syndrome (asthma, allergic rhinitis, atopic eczema)’
• = Allergy + Clinical disease entity
• Non-atopic conditions with elevated IgE: Bee venom hypersensitivity/Drug reactions
Allergy Diagnosis
• History and Examination
• Identification of the Atopic Patient
• Identification of the Causative Allergen
• Evaluation of the Patient’s Environment
• Monitoring Allergic Inflammation
Total IgE Useful for Screening:• Small children < 3 years old
• Parasite infestation not common
• Allergic Broncho-pulmonary Aspergillosis
• Non Aero-allergen Allergy – Food/Occupational
• Suspected Allergy but Negative Specific Allergy Tests
• Otherwise diagnosed allergic/atopic condition not resolving
Identification of Causative Allergen
• Skin Prick Test
• ImmunoCap – Individual / Mixed
• CAST Assay
• Other – Patch testing
• - MELISA Test
Decision on Positive RAST for Foods
• Food Decision/Cut Point (kU/l) > 2 years < 2 years
• Egg 7 2
• Milk 15 5
• Peanut 14
• Fish 20
• Soya 30
• Wheat 26
Sampson H 2003
Obstructive airway disease
All volumes reduced
FEF25-75 markedly reduced
FEV1:FVC < 80%
Measuring airway inflammationExhaled NO – screening of Inflammation with a portable device (NIOX, Aerocrine)
Alving K et al. ERS 2004. Adults
Skin and Allergy Hospital, 2005 Children
0
5
10
15
20
25
30
35
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
Mino (ppb)
Nio
x (p
pb
)
Asthma in Pre-School Children
12
The Various Marches That Set Up Asthma
Asthma
The Atopic March
Wheezing Often Persists After Bronchiolitis
• In a study of 83 children aged <2 years hospitalised with bronchiolitis, a large proportion had subsequent wheezing
Korppi M et al. Am J Dis Child 1993;146:628-631
Childrenwith
wheezing (%)
58%
76%
0
20
40
60
80
100
1-2(n=83)
2-3(n=76)
Age (years)
15
Wheezing Phenotypes
• Tuscon:
- Transient early wheezing
- Persistent early-onset wheezing
- Late-onset wheezing (Martinez FD, 1995)
• ERS Task-Force:
- Viral induced wheeze
- Multi-trigger wheeze (Brand PLP, 2008)
ERS Definitions used in the present report
• The majority of the Task Force agreed not to use the term asthma to describe preschool wheezing illness since there is insufficient evidence showing that the pathophysiology of preschool wheezing illness is similar to that of asthma in older children and adults.
Brand PLP, et al ERJ 2008
Outcome of wheeze in infancy
Martinez FD, et al. N Engl J Med 1995; 332: 133-138
Causes of Recurrent Wheezing in Infancy
AsthmaMultiple trigger wheeze
Episodic viral wheeze
Other causes
Viruses and Asthma
Atopy
Asthma
Rhinovirus
RSV
Genes
Influenza
Rhinovirus and asthma
Atopy
Decrease in lamda interferon
Increase in ICAM - 1
Rhinovirus
Asthma exacerbations Remodeling
Vitamin D deficiency
Rhinovirus and Airway Remodeling
Rhinovirus
Increased epithelial cell cytotoxicity
Increased VGEF expression and production
Angiogenesis
Remodeling
Papadopolous N. ERS 2007
Acute Exacerbations of Asthma
• Viral infection of LRT – Infects epithelial cells
Release of Type I interferon
Airway Dendritic cellls
Increase FcERI Binding IgE
Activation TH2 cells
Release IL-4/IL-13
Antigen binding
DIAGNOSING ASTHMA
Features Suggestive of Asthma• Wheezing more than 1x/ month (Evidence C)
• Activity-induced cough or wheeze (Evidence A)
• Cough at night (Evidence A)
• Absence of seasonal variation (Evidence B)
• Symptoms persisting after the age of 3 years (Evidence A)
• Symptoms worsening with certain exposures (Evidence B)
• Colds repeatedly going to the chest (Evidence B)
• Response to a bronchodilator (Evidence B)
• Response to a 10-day oral steroid course (Evidence B)
• Concomitant rhinitis, eczema or food allergies (Evidence B)
• Family history of allergy (Evidence B)
• Response to a bronchodilators in children under 5 (FEV>12%, PEFR> (FEV>12%, PEF>20% of pre-bronchodilators PEF) (Evidence A)
• Diurnal variation of PEF >20% with twice daily readings (Evidence A)
Asthma Prediction Index
Major Criteria Family history of asthma
Positive history of
atopic eczema
Positive SPT
Minor Criteria Eosinophilia > 4%
Positive history of
allergic rhinitis
Wheeze without viral infections
Asthma = 1 Major or 2 Minor
Castro-Rodriguez JA, Holberg CJ, Wright AL, Martinez FD.
A clinical index to define risk of asthma in young children with recurrent wheezing.Am J Respir Crit Care Med. 2000;162(4 Pt 1):1403-6.
56% Asthmatic Children in Pretoria Atopic
Figure 1. Inhalant Allergens. % of positive tests (Only 28 of 50 patients positive)
27%
21%9%2%5%
12%
19%5% Bermuda grass
Grass mix
Tree mix
Cat epithelium
Dog dander
HDM
Cockroach
Horse
Diagnosing Asthma in Young children
• Modified Bronchodilator Response Test : Administer a bronchodilator to the child (via spacer or nebuliser) and assess the clinical response at 10 – 15 minutes
• Bronchodilator and diary card over 2 weeks
• Trial of oral corticosteroids for 7 – 14 days
SACAWG 2009
• ‘However, the overwhelming message that should be conveyed is that there is significant difficulty diagnosing asthma in pre-school children and whatever label is given this should be continually revised and all therapies continually evaluated for efficacy.’
Motala C, et al SAMJ 2009 Motala C, et al SAMJ 2009
Differential Diagnosis of Asthma in Children < 5 Years Old• Infections:
- Recurrent respiratory tract infections
- Chronic rhino-sinusitis
- Tuberculosis
- HIV disease
• Congenital problems:
- Tracheomalacia
- Cystic fibrosis
- Bronchopulmonary dysplasia
- Congenital malformation causing narrowing of the intrathoracic airways
- Primary ciliary dyskinesia syndrome
- Immune deficiency
- Congenital heart disease
• Mechanical problems:
- Foreign body aspiration
- Gastroesophageal reflux
Other causes
• HIV-related infections
• Tuberculosis
• Foreign body
• Cardiac failure
• Cystic fibrosis
• Bronchiectasis
• ILD
• Gastro-oesophageal reflux
Small Airway Disease/Bronchiolitis
Acute
Viral
BronchiolitisAsthma
Acute exacerbation of chronic process
Chronic
Persistent
Viral induced wheeze
Multi-trigger Wheeze/Asthma
Eosinophilic Bronchiolitis
Auto-immune/CT Disease
Chronic Infection
Panbronchiolitis
Necrotising Bronchiolitis
Cystic Fibrosis
Viral-induced Wheeze
Cardiac Causes
Recurrent
Congenital/ BPD Follicular
BronchiolitisGastro-oesophageal Reflux INTERSTITIAL
LUNG DISEASE
Preschool Wheeze – Finding a Cause
Recurrent wheeze in a preschool child
Anthropometry
Thriving Not thriving
Very early age of onset
Yes No
Episodic – viral induced
Yes No
Viral-induced wheeze
Asthma
Atopic
Yes No
Other triggers (exercise, emotion, smoke)
Yes No
CXRConsider: Sweat test
TB workup
HIV workup
Induced sputum
Bronchoscopy
Immune testing
TREATING ASTHMA
T re a tm e nt O p tio n s P re -sch oo l W he e ze
M o n te lu ka s t 7 - 1 4 d a ys
E p isod ic w h e e ze
IC S orL T R A
M u ltip le trigg e r w h e e zeM ild
IC S + L A B A
P e rsis te n t a sth m aM o de ra te /S eve re
W h ee ze
If not responding – Stop Treatment and Review diagnosis
Clinical Control of Asthma
No (or minimal)* daytime symptoms
No limitations of activity
No nocturnal symptoms
No (or minimal) need for rescue medication
Normal lung function
No exacerbations* Minimal = twice or less per week
Scope of the Problem
Administration
• Inhaled therapies can be difficult to administer
Routine asthma follow-up questions
1. How often have you had asthma symptoms in the last week?
2. How often have you been woken at night because of asthma symptoms in the last week?
3. How often have asthma symptoms limited your ability to be active in the last week?
4. How many puffs of reliever medicine have you used in the last week?
5. Have you missed any days of school/work because of asthma in the last month?
Conclusion
• Asthma is difficult to diagnose in pre-school children
• Asthma is difficult to treat in pre-school children
• The most important step is trial on and off treatment
• If treatment doesn’t work – stop - think again
Acknowledgement
• Prof Refiloe Masekela
• Dr Teshni Moodley
• Dr Omolemo Kitchin
• Dr Sam Risenga
• Dr Debbie White
• Dr Carla Els
• Dr Marian Kwofie-Mensah
• Prof Max Klein
NAEP CONTACTS
• Web www.asthma.co.za
• E-mail [email protected]
• Tel 0861-ASTHMA(278462)
• Fax 088 011 678 3069
• P.O Box 72128,Parkview, 2122