Expiratory Wheezing

1. Pathophysiology
   1. Wheezing is more common in children than adults
      1. Inflammation of a child's smaller Bronchi has a greater impact on airway resistance
      2. Obstruction is more likely in a child's airway due to less chest elastic recoil
      3. A child's compliant airway walls collapse more easily under negative pressure
2. Causes: Infants
   1. Acute
      1. Asthma
      2. Infection (e.g. RSV Bronchiolitis, Bronchitis, Pnuemonia or Upper Respiratory Infection)
      3. Foreign Body Aspiration (uncommon)
   2. Chronic or Recurrent: Common
      1. Asthma
      2. Gastroesophageal Reflux
   3. Chronic or Recurrent: Uncommon or Rare
      1. Aspiration Pneumonitis
      2. Bronchopulmonary Dysplasia
      3. Congenital Lobar Emphysema
      4. Congestive Heart Failure
      5. Cystic Fibrosis
      6. Diaphragmatic Hernia
      7. Extrinsic compression by tumor (neuroblastoma)
      8. Hemosiderosis
      9. Tracheal Stenosis
      10. Tracheomalacia
      11. Tracheoesophageal Fistula
      12. Vascular Ring
      13. Visceral larval migrans
3. Causes: Children and Adolescents
   1. Acute
      1. Asthma Exacerbation
      2. Infection (e.g. RSV Bronchiolitis, Bronchitis, Pnuemonia or Upper Respiratory Infection)
      3. Foreign Body Aspiration
   2. Chronic or Recurrent: Common
      1. Asthma
      2. Allergic Rhinitis
      3. Gastroesophageal Reflux disease
      4. Obstructive Sleep Apnea (adenoid hypertrophy, also with craniofacial abnormalities)
   3. Chronic or Recurrent: Uncommon or rare
      1. a1-antitrypsin Deficiency
      2. Aspergillosis
      3. Cystic Fibrosis
      4. Ciliary Dysmotility Syndrome
      5. Sarcoidosis
      6. Tumors or Lymph node compression
      7. Vocal Cord Dysfunction
4. History
   1. Onset
      1. Onset as an infant: Congenital cause
      2. Sudden onset: Foreign Body Aspiration
      3. Winter onset with upper respiratory symptoms and with cluster of cases
         1. Respiratory Syncytial Virus (fall to spring)
         2. Croup (fall and winter)
         3. Human Metapneumovirus (winter to spring)
   2. Pattern
      1. Seasonal pattern
         1. Asthma
         2. Allergic Rhinitis
      2. Persistent or recurrent respiratory illnesses with Wheezing
         1. Cystic Fibrosis
         2. Bronchopulmonary Dysplasia
         3. Laryngomalacia
         4. Immunodeficiency (e.g. Primary ciliary Dyskinesia, Agammaglobulinemia)
      3. Associated cough
         1. Cough After feeding: Gastroesophageal Reflux
         2. Dry, nighttime cough
            1. Gastroesophageal Reflux
            2. Allergic Rhinitis
            3. Asthma
            4. Obstructive Sleep Apnea
   3. Modifying Factors
      1. Wheezing after feeding
         1. Gastroesophageal Reflux (most common)
         2. Tracheoesophageal fistula
         3. Laryngeal cleft
      2. Positional change
         1. Tracheomalacia
         2. Great Vessel anomalies
5. Signs
   1. General: Signs of chronic systemic illness (e.g. Cystic Fibrosis, Immunodeficiency)
      1. Observe for ill, wan, tired appearance
      2. Review growth charts for fall in growth velocity
   2. Wheezing Intensity
      1. Wheezing in infant heard without stethoscope suggests congenital anomaly
   3. Wheezing Modifying maneuvers
      1. Worse with neck flexion and better with extension suggests Vascular Ring
   4. Severity: Asseess for outpatient versus inpatient management
      1. Observe for respiratory distress (e.g. retractions, Wheezing)
6. Evaluation
   1. Full vital signs including Oxygen Saturation, Respiratory Rate and Peak Flows (if possible)
   2. Consider specific testing or empiric therapy in common conditions
      1. Asthma (e.g. Spirometry)
      2. Allergic Rhinitis (e.g. Allergy Testing)
      3. Gastroesophageal Reflux (e.g. barium swallow)
   3. Consider testing for uncommon conditions
      1. Cystic Fibrosis (e.g. Sweat Chloride)
      2. Immunodeficiency (e.g. Serum Immunoglobulins)
7. Imaging: Chest XRay
   1. Consider inspiratory and expiratory films (detects airway foreign bodies)
8. References
   1. Bush (2007) Prim Care Respir J 16:7-15
   2. Martinati (1995) Allergy 50:701-10
   3. Weiss (2008) Am Fam Physician 77: 1109-14