Breath Sounds (Decreased)

Decreased breath sounds represent either decreased flow of air through the airway or decreased transmission of sound across the chest wall. Lung pathology is a common etiology; however, physical causes such as obesity can be a less obvious etiology. A careful history and thorough physical examination can differentiate potentially life-threatening processes that require emergent intervention from chronic and/or benign processes. Determining whether the decrease in breath sounds is an acute or chronic process, and identifying accompanying symptoms and signs, will narrow the differential significantly.

Differential Diagnosis

Decreased airflow through respiratory tree

• Airway obstruction
  –Aspirated foreign body
  –Asthma
  –Bronchitis
  –Bronchiolitis
  –Croup
  –Epiglottitis
  –Neoplasm
  –Goiter
• Alveolar or interstitial processes
  –Pulmonary edema
  –Pneumonia
  –Pleurisy
  –Sarcoidosis
• Decreased lung expansion
  –Atelectasis
  –COPD or emphysema
  –Bronchiectasis
  –Kyphosis or scoliosis
  –Increased abdominal girth (e.g., ascites, obesity, pregnancy)
  –Pulmonary fibrosis
  –Diaphragmatic paralysis
  –Abdominal, chest wall, or pleuritic pain
  Obstructed transmission of sound
  • Obesity
  • Pleural effusion
  • Pneumothorax, hemothorax, or chylothorax
  • Pleural thickening
  • Large pulmonary embolus
  • Less common etiologies (“zebras”) include cystic fibrosis, alveolar hemorrhage, BOOP, now called COP, pneumonectomy (postsurgical), systemic lupus erythematosus, vocal cord paralysis, vocal cord dyskinesia, and psychogenic

  Workup and Diagnosis

  • History and physical examination
    –History should include associated symptoms (e.g., fever, dyspnea, wheezing, chest pain) and a detailed past medical, surgical, and exposure history
    –Physical examination should include vital signs; examination of oral cavity and neck for evidence of mass, foreign body, or tracheal deviation; inspection and palpation of the chest wall to assess for symmetric movement; percussion and auscultation of all chest fields for related abnormalities (e.g., rhonchi, wheezes, rales, rubs, egophony)
  • Initial labs may include CBC, pulse oximetry, arterial blood gas, and TSH
  • Chest X-ray is the initial imaging test
    –Associate the area of decreased breath sounds to hyperlucency or increased opacity on chest X-ray
    –Tracheal shift to a side with a density and decreased breath sounds likely signifies atelectasis or endobronchial obstruction
    –Tracheal shift away from a side with hyperlucency and decreased breath sounds may indicate tension pneumothorax
  • Lateral neck X-ray may be indicated to rule out epiglottitis (“thumb sign”)
  • If there is evidence of external airway compression, chest and neck CT scans may be needed for further evaluation
  • Pulmonary function testing

  Treatment

  • Closely monitor airway, breathing, and circulation
  • Administer supplemental O₂ as needed
  • Treat underlying etiology (e.g., removal of foreign body, bronchodilators, steroids)
  • Emergent interventions may be necessary (e.g., chest tube insertion)

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

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Copyright Details: In a Page: Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X

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