Asthma is chronic inflammatory disease of airway; which is associated with hyper responsiveness due to virus, allergens or exercise. The episodes are reversible.
It represents clinically as wheezing, breathlessness, chest tightness and coughing. There is great dyspnea, which causes restricted activities.
Pathophysiology:
- Triggering factors such as house dust, pollen, mites, cockroach residue, tobacco smoke, cold air or exercise.
- Immune response gets activated (Th2 T helper cell type 2).
- Release cytokines such as IL-4, IL-5, IL-9 and IL-13; promotes eosinophilic inflammation and IgE production.
- Release inflammatory mediators i.e. histamine and cysteinyl leukotrienes.
- Contracts smooth muscle of airway (bronchospasm), edema and increases mucous secretion which leads physical symptoms.
- Recurrent attacks causes progressive inflammation which causes decline lung function and gradually severe obstruction.
Risk factors:
- Family history: If the first relative have asthma; then the chances of developing the same to that individual increases by 6 times.
- Viral infection: Recurrent viral respiratory infection tends to have asthma in future.
-Allergy: If patient/person already have an allergic condition; asthma tends to develop.
- Occupational tobacco: Smoke tends to irritate the airways. Maternal smoking during time of pregnancy, affects the fetus growth.
- Air pollution: Exposure to smog have high chances of developing the disease.
- Obesity: Due to excess amount of fat around abdomen and chest; it does not allow the lungs to fully expand causing the symptoms.
Phenotype:
Moore and colleagues identified 5 clinical phenotype of asthma. In children 3 types of phenotype wheeze have been found:
1. Transient early wheezing: Symptoms are limited to first 3 to 5 years of age.
2. Non atopic wheezing: Symptoms are faced up to adolescence.
3. Atopic (IgE mediated) wheezing: Persistent wheezing. Allergic condition.
Classification:
1. Intermittent: Patient shows mild symptoms. It does not affect daily activities; lasts for less than 2 days/week or 2 nights/month.
2. Mild persistent: Symptoms appears more than 2 times/weeks and 4 nights/month.
3. Moderate persistent: Symptoms appear daily and at least 1 night/week. it some how limits day to day activities.
4. Severe persistent: Symptoms appear several times daily and most nights. Extremely hampers day to day activities.
Diagnosis:
It is based on medical history and physical examination.
Medical history: Symptoms like wheezing, breathlessness, chest tightness and cough are observed.
Physical examination: On auscultation; there is prolonged expiratory phase and wheezing. Watch for symptoms like allergic rhinitis, allergic dermatitis and nasal polyp.
Asthma predictive index:
More than or at least 4 wheezing episodes a year.
AND
At least 1 major criteria:
- Parental physician diagnosed asthma
- Physician diagnosed atopic dermatitis
- Allergic sensitization to at least 1 aero allergen
OR
At least 2 minor criteria:
- Wheezing unrelated to cold
- Eosinophils more than 4% in circulation
- Allergic to milk, eggs or peanuts
Pediatric Respiratory Assessment Measure (PRAM scoring) for asthma
|
Criterion
|
Description |
Score |
||
|
Oxygen
saturation |
>= 95 % 92% - 94% <92% |
0 1 2 |
||
|
Suprasternal
retraction |
Absent Present |
0 2 |
||
|
Scalene
muscle contraction |
Absent Present |
0 2 |
||
|
Air
entry |
Normal Lower at base Lower at apex and base Minimal or absent |
0 1 2 3 |
||
|
Wheezing
|
Absent Expiratory only Inspiratory (with or without expiratory) Audible without stethoscope or silent chest (Minimal
or no air entry) |
0 1 2 3 Total score
|
Work up:
Spirometry: Measures forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1)
If FEV1/FVC is less than 0.75 to 0.80; it is suggestive of asthma. Normal value in adults is 0.75 to 0.80 and in children it is 0.90.
For bronchial hyperactivity:
- Bronchoprovocation: Measurement of lung function after exposure to common asthma triggering agents.
- Sputum examination: Presence of nitric oxide level suggestive of asthma.
- Allergic skin testing: Performed using allergen according to geographic region.
Differential Diagnosis:
- Chronic obstructive pulmonary disease
- Bronchitis
- Gastro intestinal reflux disease
- Recurrent respiratory infection
- Vocal cord dysfunction
Management:
Step wise management of the episode help to reverse the condition:
- Rapid acting beta 2 agonist as needed.
- Inhaled corticosteroids (ICS)/ Leukotriene receptor antagonist (LTRA)
- Combination of ICS and LABA (Long acting beta 2 agonist) or ICS and LTRA
- Biologic therapies (ANTI IgE or Anti IL-5)
- Oral prednisone
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