01Purpose and principlesWhat the assessment is for and the core concepts behind it.
Pneumothorax is gas within the pleural space that separates lung from chest wall. Primary spontaneous pneumothorax occurs without known established lung disease, while secondary spontaneous pneumothorax complicates underlying disease and often causes greater physiological disturbance. Traumatic and iatrogenic causes include chest injury, pleural procedures, central venous access and barotrauma. An open communication between airway and pleura can sustain an air leak.
Tension pneumothorax occurs when intrapleural pressure impairs ventilation and venous return. It is a physiological state rather than an imaging measurement. Severe breathlessness, hypoxaemia, tachycardia, hypotension and peri-arrest deterioration establish urgency. Mediastinal shift may support the diagnosis on an available image but can be absent early, masked by adhesions or difficult to assess on a rotated portable film.
Radiography depends on position. In an erect patient, pleural air rises toward the apex and produces a sharp visceral line with lucency outside it. In a supine patient, air moves anteriorly and basally; deep sulcus, unusually sharp diaphragm and increased hemithorax lucency may be the only signs. Ultrasound can detect absent pleural sliding and a lung point in skilled hands, while CT resolves small or complex collections when the patient is stable.
Key points
- An erect film shows a visceral pleural line with no vascular markings peripheral to it; inspect both apices and trace the line rather than relying on general hyperlucency.
- Supine pneumothorax may collect anteriorly and basally, producing an abnormally deep costophrenic sulcus instead of the classic apical line.
- Tension is defined by physiological compromise, not mediastinal shift alone: decompress an unstable patient immediately and do not delay for imaging confirmation.
- Distinguish a true pleural line from a skin fold, scapular edge, bedding or bulla by tracing its course and checking whether lung vessels continue beyond it.
- Management integrates symptoms, physiology, underlying lung disease, occupation and patient preference; radiographic centimetres alone do not dictate every decision.
- After drainage, confirm clinical response, tube position and lung expansion and continue to assess for bleeding, surgical emphysema and persistent air leak.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
A thin visceral pleural edge with no pulmonary vessels beyond it is the central radiographic sign. Trace the line and inspect the entire hemithorax.
In a supine patient, pleural air can deepen and sharpen the lateral costophrenic angle or outline the diaphragm rather than forming an apical cap.
Severe respiratory compromise or haemodynamic instability with compatible unilateral findings requires immediate decompression before imaging.
Skin folds, clothing, scapulae and giant bullae can imitate pleural air. Lung markings beyond a broad line favour artefact, while CT may be needed before intervention in stable complex disease.
Fibrotic, emphysematous, infectious or cystic lung disease reduces reserve and alters recurrence and drainage decisions even when the visible pneumothorax seems small.
Lack of re-expansion, ongoing bubbling, worsening surgical emphysema or tube migration requires urgent system, imaging and specialist review.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Erect chest radiographyFirst step - Why
- Confirm and estimate pneumothorax and look for underlying disease or an alternative diagnosis in a stable patient.
- Interpretation and limitations
- Measure and describe using the locally adopted method, but integrate symptoms and physiology; a small image size can still be consequential in secondary disease.
- 02
Portable supine chest radiography - Why
- Assess critically ill or injured patients who cannot stand.
- Interpretation and limitations
- Search for the deep sulcus sign, increased lucency and sharply outlined diaphragm; a negative supine film is less reassuring for a small anterior pneumothorax.
- 03
Thoracic ultrasound - Why
- Detect pleural sliding and support rapid bedside diagnosis in trained hands.
- Interpretation and limitations
- Absent sliding is not specific and can occur with apnoea, pleurodesis, fibrosis or mainstem intubation; a lung point is more specific but may be absent in a large pneumothorax.
- 04
Chest CT - Why
- Resolve occult, loculated or bullous disease and associated thoracic injury in a stable patient.
- Interpretation and limitations
- CT is highly sensitive but transport and acquisition must not delay decompression of tension physiology.
- 05
Post-intervention imaging - Why
- Assess drain position, re-expansion and complication after treatment when clinically appropriate.
- Interpretation and limitations
- A radiograph complements clinical improvement and drain function; persistent symptoms despite apparent expansion require renewed cause assessment.
04Clinical next stepsHow the result changes management or prompts escalation.
01Worked case: unstable traumaDeterioration before imagingFirst stepAn adult after chest trauma becomes shocked and severely hypoxic with unilateral absent breath sounds.+
- 1Call the trauma and resuscitation team, deliver oxygen, assess airway and ventilation, and recognise suspected tension pneumothorax from the physiology and examination.
- 2Perform immediate chest decompression using the locally approved emergency technique without transferring the unstable patient for radiography.
- 3DefinitiveInsert definitive chest drainage and continue haemorrhage and injury assessment because more than one cause of shock can coexist.
- 4Verify improvement in ventilation and circulation, obtain urgent imaging when stable enough and document procedure, side, response and complications.
02Stable spontaneous presentationChoose management beyond image sizeA haemodynamically stable adult has a spontaneous pneumothorax confirmed on chest radiography.+
- 1Assess symptoms, oxygenation, underlying lung disease, pregnancy, bilateral disease, prior episodes, occupation and ability to return promptly.
- 2Discuss conservative, ambulatory, aspiration or drainage options under current pleural guidance and local expertise rather than using size alone.
- 3Provide explicit deterioration, flying, diving, smoking and follow-up advice and confirm radiographic resolution through the agreed pathway.
03Drain concernPneumothorax persists after interventionThe patient remains breathless and the lung has not re-expanded after chest-drain placement.+
- 1Reassess the patient first and inspect every connection, clamp, bottle, side hole and fixation point for a reversible system problem.
- 2Review imaging for tube position, loculation, bullous disease, airway obstruction or another cause of non-expansion.
- 3Seek early respiratory and thoracic surgical input for persistent leak, non-expanding lung, recurrence prevention or clinical deterioration.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Observe respiratory rate, oxygenation, heart rate, blood pressure, pain and work of breathing, with immediate review for any deterioration.
- For a chest drain, document swinging, bubbling, output, tube depth and connections and avoid clamping a bubbling drain unless a specialist protocol requires it.
- Reassess after decompression for physiological improvement and competing diagnoses, including haemorrhage, tamponade and airway-device malposition.
- Arrange follow-up imaging to document resolution and provide a named route for recurrence symptoms or delayed worsening.
- Discuss recurrence risk and restrictions on air travel and diving under current specialist advice, tailoring decisions to complete radiographic resolution and occupation.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Tension describes physiology
Mediastinal shift on an image is not required to diagnose tension, and shift without compromise does not substitute for clinical assessment.
Position relocates pleural air
The supine patient collects air anteriorly and basally, explaining why the deep sulcus sign replaces the familiar erect apical pattern.
Vessels expose a skin fold
A skin fold often has a broad edge with lung markings visible beyond it, whereas a true visceral line borders a vessel-free pleural space.
Reserve changes consequence
Secondary pneumothorax may cause severe symptoms at smaller visible size because diseased lung offers little ventilatory reserve.
Drain review is a system check
Persistent pneumothorax can reflect tube position, blocked tubing, loose connections, bronchopleural fistula or non-expanding lung, each requiring a different response.
07Common pitfallsFrequent interpretation and management errors.
- 01
Waiting for radiography in a haemodynamically unstable patient with a strong clinical diagnosis of tension pneumothorax.
- 02
Calling tension solely from mediastinal shift on a rotated film without assessing the patient’s physiology.
- 03
Missing a supine pneumothorax because no apical pleural line is visible.
- 04
Inserting a drain into a giant bulla mistaken for pleural air in a stable patient with complex emphysema.
- 05
Using a single size threshold without considering symptoms, reserve, secondary lung disease and access to follow-up.