What are the physical examination findings in a patient with a pneumothorax (collapsed lung)?

Physical Examination Findings in Pneumothorax

The key physical findings in pneumothorax are diminished or absent breath sounds on the affected side, hyperresonance to percussion, and decreased tactile fremitus, though clinical examination alone cannot reliably confirm or exclude the diagnosis. 1, 2

Primary Physical Examination Signs

Auscultation Findings

• Diminished or absent breath sounds on the affected side are the hallmark finding, though this sign becomes more apparent as pneumothorax size increases 1, 3
• Decreased breath sounds have a positive likelihood ratio greater than 5.0 for detecting pneumothorax, making them a moderately strong predictor when present 4
• In mechanically ventilated patients, difficulty with manual ventilation (bagging) may be the first clinical clue 5

Percussion Findings

• Hyperresonance to percussion over the affected hemithorax is a classic finding, with a positive likelihood ratio exceeding 5.0 4
• A novel technique using sternal percussion with simultaneous auscultation produces an exaggerated, resonant, and booming quality on the affected side when compared to the contralateral chest 6
• This percussion method is particularly useful in supine patients where air localizes anteriorly 6

Palpation Findings

• Decreased tactile fremitus on the affected side occurs because air in the pleural space dampens vibration transmission 4
• Subcutaneous emphysema (crepitus) may be palpable in the neck or chest wall, indicating air leak from the pleural space into soft tissues 7

Respiratory Pattern and Vital Signs

Breathing Characteristics

• Tachypnea is common, particularly in secondary pneumothorax where breathlessness is disproportionate to radiographic size 2, 8, 3
• Severe dyspnea even with small pneumothorax may herald tension physiology and requires immediate intervention 2, 8
• Respiratory rate ≥24 breaths/minute indicates clinical instability requiring urgent treatment 2

Cardiovascular Signs

• Tachycardia is an early compensatory response 5, 3
• Hypotension is NOT typical of simple pneumothorax; its presence suggests tension pneumothorax or concurrent hemothorax 5
• Narrowing pulse pressure indicates developing tension physiology 5

Critical Warning Signs of Tension Pneumothorax

Early Signs (Act Immediately)

• Marked breathlessness with rapid deterioration in cardiopulmonary status 1, 2
• Severe dyspnea, restlessness, and agitation 5
• Cool, mottled skin with delayed capillary refill 5
• Oxygen saturation decline despite supplemental oxygen 1

Late Signs (Indicates Prolonged Tension)

• Tracheal deviation away from the affected side toward the "good" lung is a LATE finding that suggests tension has been developing for some time 5
• Distended neck veins (though this can be normal in supine patients) 5
• Electromechanical dissociation (EMD) arrest in mechanically ventilated patients 1

Important Clinical Limitations and Pitfalls

Physical Examination Cannot Reliably Predict Size

• Clinical symptoms do not correlate with radiographic pneumothorax size, particularly in secondary pneumothorax where patients experience breathlessness disproportionate to actual size 2, 8
• A normal physical examination is common in mild or small pneumothorax, with signs becoming apparent only as the condition progresses 4
• Physical examination alone cannot confirm or exclude pneumothorax diagnosis 2

Special Populations Requiring Extra Vigilance

• COPD and bullous lung disease patients may have baseline decreased breath sounds and hyperresonance, making pneumothorax detection extremely difficult on examination alone 4, 8
• Mechanically ventilated patients in ICU settings frequently have missed tension pneumothorax; maintain high clinical suspicion with sudden deterioration 1
• Trauma patients may have multiple distracting injuries that obscure pneumothorax signs 3

Bedside Diagnostic Adjuncts Beyond Physical Exam

Point-of-Care Ultrasound (Preferred Bedside Tool)

• Lung ultrasound has 89% sensitivity and 99% specificity when performed by non-radiologists, superior to supine chest radiography 9, 2
• Four key sonographic signs: absence of lung sliding, absence of B-lines, absence of lung pulse, and presence of lung point 9
• The lung point sign has 100% specificity and is pathognomonic for pneumothorax 2
• Ultrasound should be your primary bedside diagnostic tool when physical examination raises suspicion 9, 2

Arterial Blood Gas Findings

• Hypoxemia is present in 75% of pneumothorax cases 2
• In secondary pneumothorax with underlying lung disease, 16% show both hypoxemia and hypercapnia 2
• The degree of hypoxemia correlates with both pneumothorax size and severity of underlying lung disease 2

Clinical Decision Algorithm

When you suspect pneumothorax based on physical findings:

1. Assess clinical stability immediately: respiratory rate, heart rate, blood pressure, oxygen saturation, and ability to speak in complete sentences 2

2. Never delay intervention in breathless patients regardless of what physical examination suggests about size 2, 8

3. Perform bedside lung ultrasound rather than waiting for chest radiography if available 9, 2

4. If tension pneumothorax is suspected clinically (marked breathlessness, hemodynamic instability, severe distress), insert a needle or chest tube immediately without waiting for imaging confirmation 1, 8