Pneumothorax: Classification, Clinical Features and Emergency

Year 4 · Internal Medicine · Respiratory — Based on the clinical lecture deck by Dr Wanami Tyson, expanded with BTS pleural disease guidance. Introduction Laennec described the clinical picture of pneumothorax in 1819 . Kjaergard (1932) gave the modern description of primary spontaneous pneumothorax in healthy people. Incidence of primary pneumothorax: 18–28 per 100,000/year in men and 1.2–6 per 100,000/year in women . Definition Pneumothorax is the presence of air or gas in the pleural space — air outside the lung, within the pleural cavity. Mechanism Normal pleural pressure is negative throughout the respiratory cycle (about −5 cmH₂O). It results from two opposing forces: the outward pull of the chest wall and the elastic recoil of the lung . When a communication forms between an alveolus (or the atmosphere) and the pleural space, air flows in until the pressure difference disappears or the leak seals . Pathophysiology Loss of negative pressure → lung recoils → ↓ lung volume → low V/Q, anatomical shunt → hypoxia ; ↓ vital capacity, ↓ PaO₂. Positive pressure (tension) → compresses great veins and heart → impaired venous return → ↓ cardiac output → hypotension (obstructive shock). Classification text Pneumothorax ├── Spontaneous │ ├── Primary (no lung disease) │ └── Secondary (underlying lung disease) └── Acquired ├── Traumatic: blunt / penetrating └── Iatrogenic: procedures, positive pressure ventilation Primary spontaneous pneumothorax (PSP) Young healthy people; rupture of apical subpleural blebs or bullae . Smoking (up to 20-fold risk) Tall, thin males Distal airway inflammation Structural bronchial abnormalities Genetic contribution (e.g. Birt–Hogg–Dubé) Secondary spontaneous pneumothorax (SSP) Common causes Rarer causes --- --- COPD (most common) Interstitial lung disease, sarcoidosis Tuberculosis Eosinophilic granuloma / histiocytosis X Asthma Lymphangioleiomyomatosis Suppurative pneumonia AIDS ( Pneumocystis pneumonia) Cystic fibrosis Lung carcinoma, chemotherapy Scleroderma, Marfan syndrome , rheumatoid disease Pulmonary infarct, granulomatosis with polyangiitis SSP is more dangerous than PSP — poor lung reserve means even a small one may cause respiratory failure. Traumatic pneumothorax Accidental: blunt trauma with rib fractures; stab or gunshot wounds Iatrogenic: positive pressure ventilation (alveolar rupture → interstitial emphysema → often bilateral); biopsy, thoracocentesis, CVP line, tracheostomy Clinical Types Closed Open Tension --- --- --- --- Pleural tear Sealed Open Ball-valve Pleural pressure < atmospheric = atmospheric atmospheric Clinical Features Constant: sudden dyspnoea and pleuritic chest pain . Uncommon: cough, haemoptysis, orthopnoea, cyanosis, tachycardia, anxiety, vague malaise. Physical examination Depends on size; vital signs often normal in small ones. ↓ chest movement on the affected side Trachea shifted away if large Tactile fremitus absent Hyper-resonant percussion Breath sounds reduced or absent Liver edge displaced down with a right-sided pneumothorax Subcutaneous emphysema (crackling) Tension pneumothorax Classically hypotension + hypoxia ; life-threatening. Rapidly progressive breathlessness, circulatory collapse (tachycardia, hypotension, sweating) Distended neck veins Tracheal deviation (late) X-ray: mediastinal shift, flattened hemidiaphragm, lung collapse More common with positive pressure ventilation and trauma In ICU: suspect in any ventilated or CPR patient who suddenly deteriorates — dyspnoea, cyanosis, marked tachycardia, hypotension, airway pressure alarms triggered . Tension pneumothorax is a clinical diagnosis — decompress before any X-ray. Investigations Chest X-ray (erect PA) Visceral pleural line with no lung markings beyond it BTS size cut-off: 2 cm rim at the hilum Supine film: deep sulcus sign , hyperlucent hemithorax CT chest Lungs obscured by surgical emphysema Distinguishes pneumothorax from a large bulla Occult pneumothorax, surgical planning Bedside ultrasound Loss of lung sliding , absent B-lines, barcode sign; lung point is diagnostic. Management Goals: re-expand the lung, remove the cause, prevent recurrence. BTS approach text Spontaneous pneumothorax ├── Bilateral or unstable → CHEST DRAIN ├── PRIMARY │ ├── Not breathless, rim <2 cm → discharge, review 2–4 weeks │ └── Breathless or rim 2 cm → ASPIRATE (16–18G) │ ├── Success → discharge, review │ └── Failure → chest drain └── SECONDARY ├── Rim 2 cm or breathless → CHEST DRAIN ├── Rim 1–2 cm → aspirate; if fails, drain; admit 24 h └── Rim <1 cm → admit, high-flow O2, observe Oxygen therapy High-concentration O₂ lowers pleural capillary nitrogen , increasing the gradient for absorption. Natural resorption is 1.25–1.8% of hemithorax volume per 24 h ; oxygen gives about a 4-fold increase . Caution in CO₂-retaining COPD. Simple aspiration First-line for all PSP needing intervention In SSP only for small (<2 cm), minimally breathless patients under 50 ; admit and observe ≥24 h Repeat aspiration