Respiratory Signs

Normal Breath Sounds

Bronchial

Bronchial sounds arise from the bronchial tree. They are loud, harsh, and high-pitched and are generally heard over the trachea under the sternum. They are predominantly heard during expiration. If bronchial breathing is heard in other parts of the lung, these sounds are abnormal.

Vesicular

Vesicular sounds arise from the lung parenchyma. They are soft, low-pitched, and predominantly heard during inspiration. They are louder towards the posterior lung bases.

Bronchovesicular

Bronchovesicular sounds are heard during inspiration and expiration and have a mid-range pitch and intensity. They are generally heard over the upper third of the anterior chest.

Clinical significance

Generally speaking, if the intensity of breath sounds is higher, this may suggest increased ventilation and pathology. Quieter breath sounds can suggest decreased ventilation.

Abnormal (Adventitious) Breath Sounds

Wheeze and rhonchi

Wheezes and rhonchi are continuous breath sounds (where they cannot be counted as discrete events). They both occur due to air moving through constricted airways (such as bronchoconstriction in asthma) and are separated by pitch. Wheezes are high-pitched (due to restricted air movement through small airways such as bronchioles), whereas rhonchi are lower in pitch (due to movement through larger airways such as tracheobronchial passages).

They both occur during expiration or both inspiration and expiration. They do not occur on inspiration alone.

Stridor

Stridor is another continuous breath sound that originates in the upper airway and occurs on inspiration. It is high-pitched and occurs due to upper airway narrowing (such as epiglottitis, croup, or anaphylaxis).

Crackles (rales)

Crackles are discontinuous and can be counted discretely. They occur due to small airways snapping open during inspiration. They can be fine or coarse depending on the size of the airway snapping open. Coarse crackles are deeper in pitch and suggest larger airways are involved, fine crackles are higher in pitch and suggest smaller airways. Crackles are seen in pneumonia, pulmonary oedema, and tuberculosis. 

Pleural friction rub

Pleural friction rubs are discontinuous sounds that occur when inflamed pleura rub against one another due to reduced lubrication. It occurs during inspiration and expiration and sounds like footsteps in fresh snow. They can be heard in pneumonia, pleuritis, and sometimes pulmonary embolism.

Other Signs

Nail clubbing

The reasons why nail clubbing occurs are not fully understood. The causes of nail clubbing can be divided into respiratory, cardiac, and other causes:

• Respiratory:
  • Lung cancer
  • Idiopathic pulmonary fibrosis
  • Tuberculosis
  • Mesothelioma
  • Sarcoidosis
  • Nail clubbing is not associated with COPD and should raise suspicion of lung cancer or other lung pathology if seen in a patient with COPD
• Cardiac:
  • Congenital cyanotic heart disease (e.g. tetralogy of Fallot, transposition of the great arteries)
  • Bacterial endocarditis
  • Atrial myxoma
• Other causes:
  • Crohn’s disease
  • Liver cirrhosis
  • Primary biliary cholangitis
  • Grave’s disease

Cyanosis

Cyanosis describes the bluish-purple colour of a person due to decreased amounts of oxygen bound to haemoglobin in the body. It can be divided into:

• Central cyanosis – due to cardiorespiratory problems leading to poor oxygenation in the lungs, caused by:
  • Respiratory disorders:
    • Pneumonia
    • Bronchiolitis
    • Severe asthma
    • Pulmonary hypertension
    • Pulmonary embolism
    • COPD
  • Cardiovascular disorders:
    • Cyanotic congenital heart disease (e.g. tetralogy of Fallot or transposition of the great arteries)
    • Heart failure
    • Myocardial infarction
  • Haemoglobinopathies:
    • Methaemoglobinaemia
    • Polycythaemia
  • Other disorders:
    • Hypothermia
    • High altitude
    • Intracranial haemorrhage – due to impaired ventilation
    • Generalised tonic-clonic seizures – due to impaired ventilation
    • Opioid overdose – due to impaired ventilation
• Peripheral cyanosis – due to inadequate/blocked circulation reaching the extremities, caused by:
  • All causes of central cyanosis
  • Heart failure
  • Hypovolaemia
  • Exposure to the cold
  • COPD
  • Peripheral arterial disease
  • Raynaud’s phenomenon

Central cyanosis causes a blue-purple discolouration around the mucous membranes of the lips and tongue as well as the extremities. Peripheral cyanosis affects the extremities and the skin around the lips but not the mucous membranes.