Understanding Lung Wheeze

By Rosalie McDonough, MD, MSc - Posted in Clinical Education
Summary:

Wheezing is a common yet concerning symptom that signals airway obstruction, often described as a high-pitched, “musical” sound during auscultation. It can be an indication of various respiratory and non-respiratory underlying conditions, ranging from asthma to heart failure. Understanding the pathophysiology of this common symptom is crucial for accurate diagnosis and effective management. This article explores the mechanisms behind wheezing, its associated symptoms, potential causes, and the diagnostic approaches that guide treatment.

Pathophysiology of wheeze

Wheezing occurs due to turbulent airflow through narrowed or obstructed airways, leading to vibration of the airway walls. This produces the characteristic high-pitched, musical sound, typically heard during expiration.1,2

Associated symptoms

Patients with wheeze often present with:

  • Shortness of breath: A sensation of not getting enough air due to obstructed airways, typically on exertion or, in severe cases, at rest.
  • Chest tightness: Discomfort or a feeling of constriction/pressure in the chest.
  • Difficulty breathing: The physical struggle or increased effort required for inhalation or exhalation of air.
Underlying causes

Wheezing can result from a variety of underlying conditions3,4 including:

  • Foreign body aspiration: Obstruction of the airway by inhaled objects, commonly seen in children.
  • Asthma: Chronic inflammation leading to bronchoconstriction and airflow limitation.
  • Chronic obstructive pulmonary disease (COPD): Exacerbations often triggered by infections, leading to increased airway resistance.
  • Bronchiectasis: Permanent dilation of bronchi associated with chronic infections, leading to mucus accumulation.
  • Bronchiolitis: Inflammation and mucus buildup in the small airways, often due to viral infections, particularly in infants.
  • Bronchitis: Acute or chronic inflammation of the bronchi, causing increased mucus production.
  • Pneumonia: Infection leading to inflammation and narrowing of the airways.
  • Cardiac asthma: Wheezing due to left heart failure causing pulmonary edema.
  • Allergic reactions: Insect stings or other allergens can induce bronchospasm.
  • Drug-induced wheezing: Particularly from NSAIDs like aspirin in sensitive individuals.
  • Smoking: Chronic exposure damages the airways, predisposing to wheeze.
  • Gastroesophageal reflux disease (GERD): Acid aspiration can cause bronchospasm and wheezing.
Diagnostic tests 

Diagnosing the cause of wheezing involves several tests, including but not limited to:

  • Clinical history: Detailed questioning about symptom onset, duration, and triggers helps narrow down the cause.
  • Physical exam: Focus on vital signs, oxygen saturation, and evidence of respiratory distress. On auscultation, wheezes can be heard throughout the chest, though they may be localized in some cases.
  • Pulmonary function tests: E.g., spirometry to assess lung volume, capacity, flow rates, and gas exchange.
  • Chest X-rays: Visualize the chest's internal structures to identify potential causes.
Spotlight auscultation: 

Wheezes are high-pitched, musical tones heard primarily during expiration, but can be heard during both phases in severe cases. In rare cases, wheezes can be heard in inspiration only.4 The sound is typically detected throughout the chest, with intensity varying based on the severity of the obstruction.5

 

Sound recorded by Eko digital stethoscope technology:

Tips for auscultation
  • Optimal positioning: Patients should be seated upright for optimal airflow.
  • Sound intensity: Varies with the severity of obstruction.
  • Radiation: Wheezing sounds often radiate bilaterally across the chest.
  • Progression: As the severity of the airway obstruction increases, wheezing may become louder and extend into the inspiratory phase. The pitch may also become higher, reflecting more significant airflow limitation.
Treatment options

Management of wheeze varies depending on the underlying cause. Examples include:

  • Bronchodilators (e.g., albuterol): Relax airway muscles to improve airflow.
  • Corticosteroids (e.g., prednisone): Reduce airway inflammation.
  • Oxygen therapy: Provides supplemental oxygen in cases of severe respiratory distress.
  • Antibiotics: Used if a bacterial infection is present.
  • Self-care: Using humidifiers, avoiding smoking, and drinking warm liquids can also help.
References

1. Kwong, CG and Bacharier, LB. (2019). Phenotypes of wheezing and asthma in preschool children. Current Opinion in Allergy &Amp; Clinical Immunology, 19(2), 148-153. https://doi.org/10.1097/aci.0000000000000516

2. Loudon R, Murphy RL Jr. (1984). Lung sounds. Am Rev Respir Dis.130(4):663-73. https://doi.org.10.1164/arrd.1984.130.4.663

3. Patel PH, Mirabile VS, Sharma S. Wheezing. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482454/

4. The American College of Allergy, Asthma, and Immunology. Wheezing, Shortness of Breath. Accessed Oct 30, 2024 from: https://acaai.org/allergies/symptoms/wheezing-shortness-of-breath/

5. Shim, CS and Williams Jr, MH. (1983). Relationship of wheezing to the severity of obstruction in asthma. Arch Intern Med. 143(5), 890-2. https://doi.org/10.1001/archinte.1983.00350050044009

6. Forgacs, P. (1978). The functional basis of pulmonary sounds. CHEST Journal, 73(3), 399-405. https://doi.org/10.1378/chest.73.3.399

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About the Author

Rosalie McDonough, MD, MSc
Rosalie McDonough, MD, MSc - Clinician Scientist

Rosalie McDonough, MD, MSc, is a clinician scientist with a diverse background in medical research and clinical practice. She earned her Master of Science degree from McGill University in Montreal, Canada, later completing her medical degree at the University Medical Center Hamburg-Eppendorf in Hamburg, Germany. Dr. McDonough’s career has spanned various fields within medicine, focusing on clinical research and health technology. Her interests have encompassed cardiopulmonary disease, lung cancer, molecular cardiology, occupational medicine, and acute ischemic stroke imaging. She is currently the Senior Manager of Medical Affairs at Eko Health.