Basics
Description
Wheezing is a continuous sound that is caused by turbulent airflow through an obstructed airway. ‚
- Often described as musical in nature and with a variable pitch
- Wheezing is an expiratory sound; stridor is an inspiratory sound.
- Wheezing occurs from obstruction in the intrathoracic airway, whereas stridor is caused by an obstruction in the extrathoracic airway.
- If heard in both inspiration and expiration, there may be a fixed obstruction or separate lesions in both the intrathoracic and extrathoracic airways.
Diagnosis
Differential Diagnosis
Extrathoracic (usually results in stridor or stertor rather than wheezing) ‚
- Nasal/nasopharynx
- Acute: nasal turbinate edema or secretions, foreign body
- Chronic: adenoidal enlargement, nasal polyps, choanal stenosis, midface hypoplasia
- Oropharynx
- Acute: peritonsillar abscess, retropharyngeal abscess, palatine tonsillitis
- Chronic: adenotonsillar hypertrophy, macroglossia, micrognathia
- Hypopharynx
- Acute: acute nasal, nasopharyngeal, or oropharyngeal obstruction
- Chronic: hypopharyngeal hypotonia, glossoptosis, obesity, neoplasia
- Larynx
- Acute: laryngospasm, laryngotracheobronchitis (croup), epiglottitis, foreign body (large and irregular)
- Chronic: laryngomalacia, papillomatosis, hemangioma, granuloma, congenital cyst or web, laryngocele
- Glottis
- Acute: vocal cord paralysis or paresis, vocal cord inflammation or polyp, psychogenic wheezing
- Chronic: paradoxical vocal cord motion (vocal cord dysfunction); psychogenic wheezing; brainstem compression; injury to the vagus, glossopharyngeal, or recurrent laryngeal nerves; papillomatosis
- Subglottis/extrathoracic trachea
- Acute: laryngotracheobronchitis (croup), bacterial, rachitic, recent endotracheal extubation
- Chronic: subglottic stenosis (congenital or after prolonged intubation), papillomatosis
Intrathoracic ‚
- Trachea (extrinsic compression)
- Acute: uncommon
- Chronic
- Vascular: vascular ring/sling, compression by an aberrant pulmonary artery
- Cardiac: left main bronchus compression, recurrent laryngeal nerve compression "cardiovocal syndrome " ¯
- Anterior mediastinum: lymphoma, thymoma, teratoma
- Middle mediastinum: lymphoma, lymphadenopathy (tuberculosis, mycotic infection, sarcoidosis)
- Posterior mediastinum: neurogenic tumors, esophageal duplication or cyst, bronchogenic cyst
- Trachea (intramural lesions)
- Acute: uncommon
- Chronic: tracheomalacia
- Congenital: cartilaginous defect (Campbell-Williams syndrome), muscular defect (Mounier-Kuhn syndrome), s/p tracheoesophageal fistula (TEF) repair, external compression/distortion, complete tracheal rings
- Acquired: chronic inflammation (recurrent infection, gastroesophageal reflux, recurrent aspiration), prolonged positive pressure ventilation, external compression
- Trachea (intraluminal lesions)
- Acute: foreign body (irregularly shaped and elongated), bacterial tracheitis (with chronic tracheostomy tube usage)
- Chronic: tracheal granulomas, hemangioma, papillomatosis, tracheal web
- Bronchi/bronchioles
- Acute: viral bronchiolitis, bronchopneumonia, foreign body (small, smooth shape), immune defect (transient hypogammaglobulinemia of the newborn is most common), granuloma, neoplasia
- Chronic: asthma, bronchopulmonary dysplasia, bronchomalacia, carcinoid, adenoma
Approach to the Patient
- Phase 1: Determine the severity of the patient 's general status and degree of respiratory distress and triage accordingly.
- Phase 2: Construct a differential diagnosis.
- Phase 3: Initiate appropriate therapies.
History
- Question: Pattern of the wheezing?
- Significance:
- A rapid onset suggests a foreign body or a postexposure exacerbation of asthma.
- A slow onset suggests an infection.
- Periods of recurrent wheezing suggest asthma.
- Nocturnal and early morning wheezing or coughing are consistent with gastroesophageal reflux, sinusitis, and/or sensitivity to common bedroom allergens.
- Wheezing in association with or soon after a meal can be seen in swallowing dysfunction, gastroesophageal reflux, or, less commonly, tracheoesophageal fistula.
- Wheezing that worsens with crying is suggestive of tracheomalacia and/or bronchomalacia or a fixed intraluminal or extraluminal obstruction.
- Question: Wheezing correlated with exertion?
- Significance: Suggests asthma triggered by exercise
- Question: Multiple exacerbations with recurrent or chronic symptoms?
- Significance:
- Recurrent cycles of exacerbations, with clearing in between, suggest a process such as asthma, cystic fibrosis, ciliary dyskinesia, and bronchopulmonary dysplasia.
- Chronic or persistent wheezing is more common with fixed anatomic abnormalities.
- Question: Common triggers?
- Significance: Could be
- Smoke
- Dust
- Animal dander
- Change in humidity or temperature
- Change in seasons (pollens, grasses, molds)
- Exercise
- Infections (usually viral)
- Inflammation of any sort
- meals (aspiration, GERD, TEF)
- Question: Family history?
- Significance: A family history of wheezing, asthma, allergic rhinitis, or atopy suggests a diagnosis of asthma.
- Question: An episode of choking preceding the first onset of wheezing?
- Significance: Suggests foreign body aspiration
Physical Exam
- Finding: Patient 's degree of respiratory difficulty?
- Significance:
- Tachypnea
- Accessory muscle usage: Use of intercostal and sternocleidomastoid muscles and abdominal musculature indicates increased expiratory effort to overcome airway obstruction.
- Nasal flaring: With increasing respiratory difficulty, the nares will be dilated to decrease the resistance to air flow.
- Finding: Auscultate: Assess airflow, adventitious sounds, and the inspiratory-to-expiratory ratio. Is the wheezing diffuse or localized?
- Significance:
- Aeration: Decreased aeration is much worse prognostically than wheezing because it is directly related to the amount of aeration and ventilation. With decreased aeration, wheezing may not be audible.
- Ratio of inspiration to exhalation: With increased intrathoracic airway obstruction, the time needed to exhale will become greater because of a greater decrease in airway caliber during exhalation. Normal ratio is 1:3.
- Localized wheezing may suggest a foreign body.
- Finding: Presence of nasal crease, the "allergic salute " ¯ (i.e., rubbing the nose with the palm of the hand), atopic dermatitis, boggy nasal turbinates, clear postnasal drainage, allergic shiners, or Dennie lines?
- Significance: Suggestive of allergic rhinitis or atopic disease including asthma
- Finding: Patients with first-time, persistent, or atypical episodes of wheezing?
- Significance: "All that wheezes is not asthma " ¯: Although most episodes of wheezing will represent viral infections or asthma, clinicians need to be mindful of alternative diagnoses.
- Finding: The 3 R 's of asthma?
- Significance:
- Recurrence: symptoms that recur multiple times with full resolution in between episodes
- Reactivity: symptoms that can be triggered during exposures (temperature extremes, smoke, dust, humid or dry air, aromas, etc.)
- Reversibility: symptoms that resolve with bronchodilator therapy
Diagnostic Tests & Interpretation
- Test: Bronchodilator responsiveness
- Significance:
- A postbronchodilator improvement in wheezing indicates a reversible process such as asthma.
- A bronchodilator may worsen wheezing in disorders of airway wall rigidity such as bronchomalacia or tracheomalacia.
- There may be no change following a bronchodilator in situations with foreign bodies, fixed airway obstruction due to significant inflammation (i.e., status asthmaticus), or airway remodeling.
- Test: Pulmonary function testing (spirometry)
- Significance:
- Spirometry remains the standard and most helpful measure of pulmonary function.
- Normative data have been described in children >6 years of age.
- Normal spirometry does not rule out asthma.
- Methacholine challenge test is a provocative test to evaluate for asthma.
- Exercise test with spirometry to evaluate for exercise-induced asthma
- Test: Pulse oximetry measurement of oxygen saturation (Spo2)
- Significance: Pulse oximetry is an insensitive measure of mild to moderate respiratory difficulty during wheezing, but oxyhemoglobin saturation <92% may be seen in severe compromise.
- Test: Arterial blood gas
- Significance:
- Arterial blood gases provide a direct measure of oxygenation (Pao2) and ventilation (Paco2) and can also help to determine severity.
- A normal or high normal Paco2 in a tachypneic patient (when it should be low) may be a sign of impending respiratory failure.
Lab
- Test: Microbiologic studies
- Significance:
- Positive bacterial culture of sputum is helpful in directing or focusing antibiotic therapy. A Gram stain showing sheets of polymorphonuclear leukocytes and a predominant organism is helpful to differentiate a potentially causative organism from the multitude of normal flora.
- Positive respiratory virus screen or culture (often within 12 hours) can prevent needless antibiotic therapy and may be helpful in predicting future disease.
- Test: Tuberculosis skin test
- Significance: Mantoux purified protein derivative " ”tuberculosis. May be falsely positive in a patient who received BCG vaccine. May be falsely negative in a patient who is anergic.
- Test: CBC including eosinophil count, quantitative immunoglobulins, IgE, complement, HIV testing, allergy skin testing
- Significance: Screening for immune defects, atopy
Imaging
- Chest radiography (posteroanterior and lateral views)
- Should be strongly considered in all patients with new-onset wheezing or an asymmetric lung exam
- Can show findings suggestive of airway obstruction (hyperinflation, hyperlucency, flattening of the diaphragms)
- Asymmetry in aeration on right and left lateral decubitus films suggests foreign body or other obstructing lesions on the side having the greatest air trapping.
Treatment
Additional Treatment
General Measures
- A trial of bronchodilator therapy (e.g., albuterol) may be both therapeutic and diagnostic of the reversible airway obstruction characteristic of asthma.
- For acute asthma exacerbation: corticosteroids PO or IV
- Ipratropium bromide may be helpful in reducing airway secretions and reducing airway obstruction, but it is not FDA approved for treatment of asthma. May be helpful in tracheomalacia as might bethanechol.
- Inhaled corticosteroids, antileukotriene agents, and, less, frequently methylxanthines (aminophylline and theophylline) are used as maintenance medications.
- Antibiotics should be used in patients with suspected pneumonia.
- In emergency setting epinephrine, terbutaline, and magnesium sulfate can be used along with supportive care such as supplemental oxygen.
Alert
Factors that may indicate a respiratory emergency: ‚
- Signs of mild to moderate respiratory difficulty: tachypnea, intercostal and suprasternal retractions, nasal flaring, head bobbing and exaggerated shoulder movement during breathing, abdominal breathing and subcostal retractions (may be normal in infants, especially during active [REM] sleep), relative difficulty speaking in complete sentences, significant wheezing, prolonged exhalation, and low Paco2 in the face of tachypnea
- Signs of impending respiratory failure: cyanosis, fatigue, inability to speak in >1- or 2-word phrases, altered mental status (e.g., confusion, agitation), decreased respiratory drive, inadequate ventilation (poor air flow), no audible wheezing, high normal or rising Paco2 in the face of tachypnea or respiratory distress
- Determine which patients require assisted ventilation (e.g., bag-mask ventilation, noninvasive [nasal] ventilation, or endotracheal intubation)
- Lack of response to aggressive bronchodilator therapy, without a history of asthma or recurrent wheeze, or biphasic adventitious sounds should immediately raise the suspicion of a fixed lesion.
Additional Reading
- Castro-Rodriguez ‚ JA, Rodrigo ‚ GJ. Efficacy of inhaled corticosteroids in infants and preschoolers with recurrent wheezing and asthma: a systemic review with meta-analysis. Pediatrics. 2009;123(3):e519 " “e525.
- Cowan ‚ K, Guilbert ‚ TW. Pediatric asthma phenotypes. Curr Opin Pediatr. 2012;24(3):344 " “351. ‚ [View Abstract]
- Nelson ‚ KA, Zorc ‚ JJ. Asthma update. Pediatr Clin North Am. 2013;60(5):1035 " “1048. ‚ [View Abstract]
- Piippo-Savolainen ‚ E, Korppi ‚ M. Long-term outcomes of early childhood wheezing. Curr Opin Allergy Clin Immunol. 2009;9(3):190 " “196. ‚ [View Abstract]
Codes
ICD09
ICD10
SNOMED
- 56018004 Wheezing (finding)
- 9763007 expiratory wheezing (finding)
FAQ
- Q: What percentage of recurrent wheezing resolves by school age?
- A: Roughly 40% of children with ≥1 episode of wheezing before 3 years clear by 6 years of age.
- Q: Should chest radiographs be routinely obtained in children experiencing their first episodes of wheezing?
- A: For a child with new-onset asymmetric wheezing, a chest radiograph should be obtained. For a child with symmetric wheezing, chest radiography may not be helpful and should be ordered judiciously.