1. Asthma
Dr. Tara Husain

2. Definition;
is defined as reversible obstruction of large and small airways as a result of hyper-responsiveness to various immunologic and non immunologic stimuli

3. Risk factors Environment; inhaled allergens
respiratory viral infections
chemical and biologic air pollutants
Biological and genetic factors

4. EARLY CHILDHOOD RISK FACTORS FOR PERSISTENT ASTHMA
Parental Asthma
History of other allergy
Sever lower respiratory tract infection
Wheezing apart from colds
Male gender
Low birth weight
Exposure to tobacco smoke
Reduced lung function at birth

5. Pathogenesis; Smooth m contraction Cellular infiltrate
edema, basement membrane
mucus hypersecretion
smooth m and mucous gland hypertrophy

6. Infants are more susceptible to airway obstruction due to;
Smaller airway size.
Lower elastic recoil of the lung.
Decreased smooth muscle support of the small airways.
Relative mucus gland hyperplasia.
Decreased collateral channels of ventilation between the alveoli

7. Asthma triggers; viral infections
Aeroallergens (animal dander, dust mites)
Seasonal aeroallergens ( Pollens)
tobacco smoke
Air pollutants;( Ozone, Sulfur dioxide)
Strong or noxious odors
Cold , dry air
Exercise
Crying, laughter, hyperventilation

8. Aggravating factors in asthma
Gastroesophageal reflux
Rhinitis
Sinusitis

9. Clinical Manifestations
Intermittent dry coughing and expiratory wheezing are the most common symptoms
shortness of breath and chest tightness
symptoms can be worse at night
Daytime symptoms, often linked with physical activities
symptoms can be subtle ; (limitation of physical activities, general fatigue ,or sleep disturbance)
Lack of improvement with bronchodilator and corticosteroid is inconsistent with the diagnosis of asthma

10. Examination; expiratory wheezing and a prolonged expiratory phase
Decreased breath sounds in some of the lung fields, commonly the right lower posterior lobe, are consistent with regional hypoventilation owing to airways obstruction.
Crackles and rhonchi can sometimes be heard, resulting from excess mucus production and inflammatory exudate in the airways

11. Differential diagnosis;
Chronic rhinitis
Sinusitis
Adenoidal or tonsillar hypertrophy
Laryngotracheobronchomalacia
Laryngotracheobronchitis
Vocal cord dysfunction
Foreign body aspiration
Viral bronchiolitis
Gastroesophageal reflux
Tuberculosis
Heart failure

12. Diagnosis; Mainly clinical Pulmonary function test Radiography
Skin test
Radioallergosorbent (RASTA) test

13. Pulmonary function test
Tidal volume
Is the lung volume representing the normal amount of air displaced between normal inhalation and exhalation with no extra effort applied

14. Total lung capacity;
is the maximum volume to which the lung can be expanded with the greatest possible inspiratory effort;
TLC= VC +RV

15. Vital capacity;
Is the maximum amount of air the person can expel from the lung after first filling the lung to the maximum extent

16. Functional residual volume and residual volume;
Functional residual capacity; is the volume of air present in lung at the end of passive expiration
Residual volume; is the amount of air left in the lung after maximum exhalation

17. Spirometry objective measure of airflow limitation
Measures the forced expiratory volume in one second.
usually feasible in children > 6 yr
FEV1 is within 5% on 3 attempts, then the highest FEV1 effort of the 3 is used
Normal values are based on height, gender, and ethnicity.
typically decreases in asthmatics by > 15% after exercise challenge

18. Pulmonary function test;
useful in evaluating an older child’s functional status, although they rarely yield an etiological diagnosis
Abnormalities described in form of obstructive or restrictive lung disease

19. obstructive disease; there is low flow rate and increased residual volume RV and functional residual volume FRV
Restrictive disease; there is low vital capacity and total lung capacity with relative preservation of flow rates and FRV.
A significant increase in pulmonary function test after bronchodilator therapy indicate reactive airway disease

20. Chest X-ray;
often appear to be normal, aside of subtle nonspecific finding of hyperinflation and peribronchial thickening.
CXR is not routine in asthmatic patients

21. Indications of chest x-ray;
1- First attack of bronchospasm.
2- localized wheeze or other finding on osculation.
3- High grade fever or toxic appearance.
4- Sudden deterioration in patients condition despite treatment with signs suspecting pneumothorax.
5- suspicion of foreign body.

22. Skin test; There are 2 methods; 1-Prick or puncture technique.
2-Intradermal injection technique

23. Radioallergosorbent (RASTA) test;
This is an in vitro test to determine the presence of antigen specific IgE in serum of the patient.

24. asthma masqueraders aspiration pneumonitis bronchiolitis obliterans
cystic fibrosis
allergic bronchopulmonary mycoses (aspergillosis)
ciliary dyskinesias
immune deficiencies