8. Pneumothorax (including Tension Pneumothorax)

Quick Recap

Nests under Acute Respiratory Failure / Airway Emergencies.

1. Definition

Presence of air in the pleural space, causing partial or complete lung collapse.

• Primary spontaneous: no underlying lung disease (typically tall, thin young males, smoking-associated)
• Secondary spontaneous: underlying lung disease (COPD, ILD, cystic/bullous disease, necrotizing infection, malignancy)
• Traumatic: penetrating or blunt chest trauma
• Iatrogenic: central line placement, thoracentesis, lung biopsy, mechanical ventilation (barotrauma)
• Tension pneumothorax: a one-way valve mechanism allows air into the pleural space on inspiration but prevents its escape on expiration -> progressive intrapleural pressure rise -> lung collapse, mediastinal shift, compression of intrathoracic vasculature -> obstructive shock. This is the most serious consequence and a clinical (not radiographic) diagnosis requiring immediate treatment.

2. Pathophysiology

Air enters the pleural space (via visceral pleural breach — ruptured bleb/bulla, necrotic lung, direct injury — or parietal pleural breach — penetrating trauma, line placement) faster than it can be reabsorbed or drained, causing loss of the negative intrapleural pressure that normally keeps the lung expanded -> collapse. In tension physiology, progressively rising intrapleural pressure compresses the ipsilateral lung, shifts the mediastinum contralaterally, kinks the great veins, and reduces venous return -> obstructive shock physiology superimposed on hypoxemic respiratory failure. Positive-pressure ventilation dramatically accelerates this process, which is why tension pneumothorax classically presents with sudden decompensation in a ventilated patient.

3. Immediate Stabilization (ABCDE)

Recognize tension pneumothorax on clinical grounds — do NOT wait for imaging if unstable:

• Hypotension, distended neck veins, absent/decreased breath sounds unilaterally, tracheal deviation away from the affected side (late/unreliable sign), significant subcutaneous emphysema, absent lung sliding on POCUS
• Suspect strongly in: mechanically ventilated patients who suddenly decompensate, patients with a known stable pneumothorax who suddenly worsen, and any instability during/after a procedure known to risk pneumothorax (central line, thoracentesis, biopsy)

Airway: secure if respiratory failure/shock precludes spontaneous ventilation; recognize that positive pressure ventilation itself can convert a simple pneumothorax to tension physiology.

Breathing/Immediate decompression for tension pneumothorax:

• Needle decompression: insert in the 5th intercostal space, mid-axillary line (NOT the traditionally taught 2nd intercostal space/mid-clavicular line, which is now considered less reliable due to variable chest wall thickness) OR finger thoracostomy if skill/situation allows (more reliable, especially in trauma/hemothorax-associated cases)
• Needle decompression is a temporizing measure only — it can fail to fully relieve tension or the pneumothorax can recur; follow immediately with formal tube thoracostomy
• If intubated and sudden decompensation occurs: assess lung sliding via POCUS first if time allows (rapid, reliable), otherwise proceed directly to decompression on clinical suspicion alone

Circulation: treat obstructive shock physiology as a direct consequence of tension pneumothorax — decompression IS the resuscitation; fluids are adjunctive, not primary treatment.

Disability/Exposure: examine for associated injuries if traumatic; assess for subcutaneous emphysema extent.

Checklist:

4. Focused History

Sudden-onset pleuritic chest pain and dyspnea (spontaneous); recent trauma (mechanism, penetrating vs blunt); recent procedure (central line, thoracentesis, lung biopsy, bronchoscopy); underlying lung disease (COPD, ILD, cystic fibrosis, necrotizing pneumonia, malignancy — secondary spontaneous risk); smoking history and body habitus (primary spontaneous risk — tall, thin, young males); mechanical ventilation with high pressures/volumes (barotrauma risk); prior pneumothorax episodes (recurrence risk).

5. Examination + POCUS

Decreased/absent breath sounds unilaterally, hyperresonance to percussion, decreased tactile fremitus, subcutaneous emphysema, tracheal deviation (late sign, unreliable), signs of hemodynamic compromise if tension.

POCUS (rapid, reliable, preferred over CXR in unstable patients): absence of lung sliding, absence of B-lines, presence of a "lung point" (transition between sliding and non-sliding lung — pathognomonic for pneumothorax and helps estimate size), "barcode/stratosphere sign" on M-mode (absent normal "seashore sign").

6. Syndrome Identification

Pleural air collection with lung collapse; escalate mentally to "tension physiology until excluded" in any unstable or acutely decompensating patient, especially ventilated patients or those post-procedure.

7. Differential Diagnosis

8. Severity Assessment

Severity determined clinically (hemodynamic stability, degree of respiratory compromise, tension vs non-tension) more than by radiographic size alone. Percentage lung collapse on CXR (small vs large, using standard measurement methods) guides observation vs intervention decisions in stable primary spontaneous pneumothorax.

9. Investigations

• Bedside (mandatory in unstable patients): POCUS lung sliding assessment — do not wait for CXR if tension suspected and patient unstable
• Imaging (stable patients): upright CXR; CT chest if diagnosis unclear, large bullae need to be distinguished from pneumothorax, or to characterize underlying lung disease/bronchopleural fistula
• Caution: in patients with cystic/emphysematous lung disease, large bullae can mimic pneumothorax on standard CXR — attempted chest tube placement into a bulla causes significant morbidity; get CT if any doubt in a stable patient

10. POCUS

Central to both diagnosis and rapid rule-out. Absent lung sliding + absent B-lines + lung point = pneumothorax, with the lung point location giving a rough size estimate. In a ventilated patient with sudden desaturation/hypotension, POCUS lung sliding assessment takes seconds and should be part of the first-line rapid differential alongside auscultation.

11. Evidence-Based Management

Tension pneumothorax: immediate needle or finger decompression (5th ICS, mid-axillary line) -> formal tube thoracostomy without delay (Section 3).

Simple/non-tension pneumothorax — management depends on type and stability:

• Primary spontaneous, small, minimally symptomatic, stable: observation with supplemental oxygen (accelerates air reabsorption) and serial imaging may be appropriate in selected patients per local protocol
• Primary or secondary spontaneous, large, symptomatic, traumatic, or iatrogenic: tube thoracostomy is the mainstay
• Secondary spontaneous pneumothorax: typically requires tube thoracostomy and may need pleurodesis for definitive/recurrence-prevention management given underlying lung disease
• Pneumothorax in a mechanically ventilated patient: always requires tube thoracostomy (positive pressure ventilation will not allow spontaneous resolution and risks tension conversion)

Chest tube size/technique by indication (French sizing, 3F = 1mm outer diameter):

• Simple pneumothorax (primary/secondary/traumatic/iatrogenic): 8-14F, image-assisted guidewire (Seldinger) technique
• Loculated pneumothorax: 8-14F, image-assisted guidewire
• Pneumothorax in a patient on positive pressure ventilation: 20-28F, guidewire OR blunt dissection
• Bronchopleural fistula: >=28F, blunt dissection
• (Hemothorax, for reference: >32F, blunt dissection)
• Small-bore tubes (SBCTs, 8-14F) are increasingly favored — equally efficacious to large-bore tubes for most indications, better tolerated, fewer complications; large-bore tubes retain traditional use for ventilated patients and bronchopleural fistula due to theoretical concern about adequate drainage

Chest tube removal criteria: pneumothorax resolved, no air leak present, lung remains expanded on water seal for 24 hours. If uncertainty remains, clamp trial for 4-8 hours followed by repeat CXR before removal.

Persistent air leak (>72 hours) / bronchopleural fistula: difficult, multidisciplinary problem. Options: continued chest tube drainage, endoscopic management (tissue sealants, glue, silver nitrate, endobronchial one-way valves — effective for localized injury identifiable by bronchoscopy with balloon occlusion, not for diffuse lung injury), or surgical repair. Most common cause is post-pulmonary-resection; other causes include necrotizing infection, trauma, ruptured bullae, iatrogenic injury.

12. Organ Support

Supplemental oxygen (accelerates pleural air reabsorption in addition to treating hypoxemia); avoid unnecessary high airway pressures/PEEP if a pneumothorax is undrained or a bronchopleural fistula is present; standard ICU supportive care once stabilized.

13. Consultation Matrix

14. Monitoring Framework

Serial clinical reassessment and CXR after chest tube placement, monitor for air leak (bubbling in the water seal chamber), monitor for re-expansion pulmonary edema after rapid large-volume drainage (rare but recognized complication), watch for recurrent tension physiology if tube function is uncertain (kinking, clot, malposition).

15. ICU Bundle Checklist (Daily)

16. Complications

Recurrent tension physiology (tube malfunction/malposition), re-expansion pulmonary edema (rapid drainage of a large/chronic pneumothorax), bleeding/organ injury from tube insertion, infection (empyema), persistent air leak/bronchopleural fistula, pneumothorax recurrence (higher in secondary spontaneous and untreated primary spontaneous without pleurodesis). Prevention: correct decompression site/technique, appropriate tube size selection, careful insertion technique. Rescue: repeat decompression/tube placement, surgical/endoscopic management of persistent leaks.

17. Escalation & De-escalation

Escalate: any sign of tension physiology -> immediate decompression; ongoing large air leak or failure to re-expand despite tube drainage -> surgical/interventional pulmonology referral.

De-escalate/remove tube: per Section 11 removal criteria.

18. ICU Discharge Criteria

Chest tube removed (or persistent air leak being managed on an established outpatient/step-down pathway), no respiratory distress, stable on room air or baseline oxygen requirement, underlying cause addressed or being followed (e.g., smoking cessation counselling for primary spontaneous, oncology/pulmonology follow-up for secondary spontaneous).

19. Documentation & Medicolegal Checklist

20. Key Guidelines

British Thoracic Society Pleural Disease Guidelines; ATS/relevant thoracic society guidance on pneumothorax management as reflected in Washington Manual of Critical Care Ch. 17 (Pleural Disorders) and general trauma/ATLS principles for tension pneumothorax recognition and needle decompression site.

21. Controversies

Optimal chest tube size remains debated — growing evidence supports small-bore tubes for most indications (equal efficacy, better tolerability) even as large-bore tubes remain traditionally favored for ventilated patients and bronchopleural fistula, without strong RCT evidence settling the question definitively. Observation vs intervention threshold for primary spontaneous pneumothorax (size cutoffs, symptom thresholds) varies between guidelines/regions. Needle decompression site (5th ICS mid-axillary vs traditional 2nd ICS mid-clavicular) has shifted in recent teaching based on chest wall thickness data, but practice variation and retraining lag persist.

22. References

1. Pleural Disorders in the Intensive Care Unit (Wayne M, Chen AC). Washington Manual of Critical Care, 4th ed, 2025 (Ch. 17).
2. Chest Tube Insertion (Patel TM, Chenna PR). Washington Manual of Critical Care, 4th ed, 2025 (Ch. 81).
3. General Management of Trauma. ICU Protocols: A Step-wise Approach, 2nd ed. Springer; 2020 (Ch. 10).
4. Trauma-related pneumothorax/tension pneumothorax chapters. Washington Manual of Critical Care, 4th ed, 2025.
5. British Thoracic Society Pleural Disease Guideline, current edition.