Asthma physical examination

Overview
The characteristic physical signs of asthma include: loud prolonged polyphonic expiratory wheeze and adventitious sounds such as rhonchi. Presence of wheeze is indicative of airway narrowing; however, the absence of wheeze indicates a silent lung characteristic of status asthmaticus delineated by widespread obstruction that results in significant airflow reduction and insufficient enough to produce a wheeze.

Clinical Presentation
Physical examination may be normal or can be characteristically present with a loud polyphonic expiratory wheeze. Nasal examination is mandatory to rule out associated conditions such as, aspirin sensitivity or allergic rhinitis.

Mild Episode

 * Prolong end-expiratory wheeze
 * In between attacks, chest is clear and no abnormal physical signs may be detectable.

Moderately Severe Episode

 * Use of accessory muscles of respiration such as sternocleidomastoid and scalene muscles
 * Increased respiratory rate
 * Pulsus paradoxus (a fall of SBP between 10-20mmHg during inspiration)
 * Hyper-resonant lungs
 * Loud prolonged expiratory wheeze with a reduced inspiration to expiration ratio
 * Vesicular breath sounds with prolonged respiration

Acute Severe Episode

 * Patient has to sit upright with arms extended to support the upper chest (tripod position) that assist the use of accessory muscles of respiration
 * Use of accessory muscles of respiration
 * Increased respiratory rate greater than 30 cycles per minute
 * Increased heart rate
 * Pulsus paradoxus (a fall of SBP greater than 20-40 mmHg during inspiration)

Imminent Respiratory Failure

 * Profuse sweating
 * Severe hypoxia resulting in central cyanosis and hypoventilation
 * Paradoxical thoraco-abdominal breathing
 * Pulsus paradoxus, wheeze and breath sounds are typically absent secondary to severe airway obstruction, representing a silent chest which is an ominous sign.

Chronic Asthma

 * Persistent scattered rhonchi

Associated Conditions

 * Conjunctival congestion, transverse crease on nose as a consequence of constant rubbing and pale swollen nasal mucosa are suggestive of associated allergic rhinitis.
 * Triad of asthma, nasal polyps and rash is indicative of aspirin sensitivity.
 * Presence of clubbing in asthma may be secondary to interstitial lung disease.