Secondary spontaneous pneumothorax

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Air enters the pleural space through rupture of diseased lung, a cyst, cavity or tumour. Loss of negative pleural pressure collapses already compromised lung and can sharply worsen ventilation–perfusion matching. Positive-pressure ventilation may expand the leak and convert a stable pneumothorax to tension, so deterioration around NIV or intubation demands immediate reassessment.

Management balances current physiology, pneumothorax size and trajectory, air-leak persistence, the underlying disease and recurrence consequences. Compared with primary pneumothorax, thresholds for admission, drainage and recurrence prevention are lower. Ambulatory devices are possible only in carefully selected patients through an experienced service with reliable follow-up and immediate return access.

Recurrence prevention can include surgical bullectomy and pleurodesis or medical pleurodesis when surgery is unsuitable. Timing is individual: a first secondary episode with severe physiological compromise, high-risk occupation or limited reserve may justify definitive discussion. Apply the valid 2023 BTS pleural guideline, current procedure statement and local thoracic service rather than using older algorithms uncritically.

Key points

Secondary spontaneous pneumothorax occurs without trauma in a person with underlying lung disease, commonly COPD, interstitial lung disease, cystic fibrosis, infection, malignancy or cystic lung disease.
The same radiographic air rim causes more severe hypoxaemia and breathlessness than in primary pneumothorax because the remaining lung is already impaired.
Pleuritic pain, sudden dyspnoea and unilateral reduced breath sounds are typical, but examination can be subtle in hyperinflated or fibrotic lungs.
Tension is a physiological diagnosis of obstructive shock, not a measurement of pneumothorax size. Decompress immediately when clinical compromise is present.
Use chest radiography to confirm and estimate a stable pneumothorax; CT helps distinguish a small pneumothorax from giant bullae or loculated air when uncertainty changes intervention.
Most symptomatic or clinically important secondary pneumothoraces require admission and pleural intervention. Follow the current BTS decision pathway rather than a remembered size cutoff alone.
Small-bore image-guided chest drainage is appropriate for many stable cases; choose site and device for anatomy, air leak, underlying disease and local expertise.
Do not clamp a bubbling drain. Routine early suction is not automatically beneficial and can worsen re-expansion injury or air leak; use specialist direction.
Persistent air leak, failure of re-expansion or recurrence needs early thoracic-surgical and pleural MDT discussion, with blood patch or endobronchial options when surgery is unsuitable.
Smoking cessation, recurrence counselling, air-travel advice and occupation or diving restrictions are part of treatment, not discharge footnotes.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

COPD and emphysema

Rupture of fragile bullae or subpleural emphysematous lung is a common cause and leaves little reserve when lung volume is lost.

Fibrotic or cystic lung disease

Interstitial fibrosis, cystic fibrosis, lymphangioleiomyomatosis and other cystic disorders create structurally weak subpleural spaces, with the final risk shaped by exposure and individual susceptibility.

Infection and necrosis

Pneumocystis, tuberculosis, bacterial abscess and other infections can rupture cavities or injured subpleural lung into pleura.

Malignancy and rarer disorders

Primary or metastatic tumour, catamenial thoracic disease and connective-tissue conditions are less common but important contextual causes.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Diseased-lung rupture
A bulla, cyst, cavity or fragile fibrotic region breaches visceral pleura and leaks alveolar air, contributing to the resulting loss of respiratory reserve.
2
Loss of pleural coupling
Air abolishes local negative pleural pressure, allowing affected lung to recoil and collapse, with effects that increase as the pathological process progresses.
3
Disproportionate gas-exchange loss
Even a modest pneumothorax removes functioning volume from an already impaired lung, worsening ventilation-perfusion mismatch and hypoxaemia.
4
Persistent leak tendency
Poor tissue integrity and ongoing disease make spontaneous sealing less reliable than in otherwise healthy lung.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Stable secondary pneumothoraxRed flag

New unilateral pleuritic pain or breathlessness with a pleural line and absent peripheral lung markings in a person with established lung disease; oxygen need may exceed apparent radiographic size.

Tension physiologyRed flag

Hypotension, severe hypoxaemia, agitation or reduced consciousness, tachycardia and unilateral reduced ventilation indicate obstructive compromise. Tracheal deviation is late and not required.

Persistent air leakRed flag

Continued bubbling, failure of lung re-expansion or recurrent air after several days suggests a bronchopleural or alveolar–pleural fistula and requires early specialist planning.

Underlying high-recurrence disorder

LAM, Birt–Hogg–Dubé syndrome, cystic fibrosis and some fibrotic diseases carry distinctive bilateral or recurrent risk and should trigger specialist disease assessment.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

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
ABCDE assessment, pulse oximetry and arterial blood gasFirst step
Why
Define immediate respiratory compromise and hypercapnic risk in the underlying lung disease.
Interpretation and limitations
Do not delay decompression for tests in tension physiology. A normal saturation on oxygen can conceal worsening hypercapnia, particularly in COPD.
02
Erect inspiratory chest radiograph
Why
Confirm pleural air, assess extent and identify underlying or contralateral disease.
Interpretation and limitations
Estimate using the current BTS method and combine with symptoms and reserve. Expiratory films are not routinely needed; supine films can miss anterior pneumothorax.
03
Thoracic ultrasound
Why
Rapidly support pneumothorax recognition and guide pleural procedures in trained hands.
Interpretation and limitations
Absent sliding is not specific and adhesions or bullae can mislead. A lung point supports pneumothorax, but ultrasound does not replace urgent clinical decompression in shock.
04
CT thorax
Why
Resolve uncertainty between pneumothorax and bullous or loculated disease and plan complex drainage or surgery.
Interpretation and limitations
Use in stable patients when the result changes care; moving an unstable patient to CT is unsafe. CT can reveal a causal cavity, tumour or cystic disorder.
05
ECG, FBC, renal profile and inflammatory markers
Why
Find competing acute coronary, infectious, anaemic or metabolic contributors and prepare for intervention.
Interpretation and limitations
Tests do not diagnose pneumothorax. Leukocytosis can reflect stress; fever or cavitation should raise infection and bronchopleural-fistula concern.
06
Post-intervention chest imaging and drain assessment
Why
Confirm re-expansion, drain position and ongoing air leak.
Interpretation and limitations
Correlate with bubbling, symptoms and subcutaneous emphysema. A non-expanding lung may reflect obstruction, trapped lung or a large fistula rather than inadequate suction.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

COPD exacerbation

Worsening wheeze and breathlessness may be assumed to be an exacerbation; sudden pain, asymmetry and pleural imaging identify pneumothorax.

Pulmonary embolism

Acute pleuritic symptoms and hypoxaemia overlap, and thromboembolic risk may require assessment even after another abnormality is found.

Giant bulla

A large intrapulmonary air space can resemble pleural air; CT or expert imaging review prevents hazardous drain placement.

Pneumonia

Fever, sputum and focal consolidation support infection, which can also precipitate a pneumothorax in damaged lung.

Pleural effusion

Fluid causes dullness and basal opacity rather than pleural air, while hydropneumothorax may contain both and signal fistula.

Additional chapter-specific clues

Bullous-lung mimicRed flag

A giant bulla may appear as a large lucent area and can be entered catastrophically by a drain; CT is valuable when the patient is stable and radiography is uncertain.

Iatrogenic or traumatic alternativeRed flag

Recent biopsy, central-line insertion, ventilation or chest injury changes classification and may require a trauma or procedural pathway rather than spontaneous-pneumothorax algorithms.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Immediate threatDecompress tension without imaging delayFirst stepPneumothorax is suspected with severe respiratory or haemodynamic compromise.

1Call for senior emergency and critical-care help, give high-concentration oxygen initially if critically ill, and monitor continuously.
2Perform immediate decompression using the locally approved technique and trained expertise; do not wait for a chest radiograph.
3DefinitiveInsert a definitive chest drain through the emergency pleural or trauma pathway and reassess circulation and ventilation.
4Look for precipitating positive pressure, underlying disease and contralateral pathology, then document the event and recurrence plan.

02Stable presentationUse physiology and reserve, not size aloneImaging confirms secondary spontaneous pneumothorax without tension.

1Admit or observe in an appropriate monitored setting, prescribe oxygen to target and provide analgesia.
2Apply the current BTS pathway using symptoms, pneumothorax extent, underlying reserve and ability to access follow-up.
3Use an image-guided small-bore drain for most clinically important cases; ambulatory management requires a specialist service and selected patient.
4EscalationRepeat clinical assessment and imaging at the pathway interval, escalating immediately for increasing air, oxygen need or distress.

03Air leakRestore expansion and escalate earlyEscalationThe drain bubbles persistently or the lung fails to re-expand.

1Check the patient, tubing, connections, drain depth and position; identify blockage, disconnection or a separate loculated pneumothorax.
2Do not clamp a bubbling drain. Discuss suction only with the pleural team after correct drainage and re-expansion strategy are reviewed.
3Refer early to thoracic surgery for repair and pleurodesis assessment rather than waiting for prolonged leak and deconditioning.
4If surgery is unsuitable, consider specialist autologous blood pleurodesis, chemical pleurodesis or endobronchial intervention according to local expertise.

04Prevention and dischargeReduce recurrence and pressure-related harmDefinitiveThe pneumothorax has resolved or definitive treatment is being planned.

1Provide smoking-cessation treatment and investigate a previously unrecognised causal lung disorder when indicated.
2Discuss surgical or medical recurrence prevention after recurrent episodes, severe first-event compromise, persistent leak or high-consequence circumstances.
3Advise no air travel until at least seven days after full radiographic resolution and specialist review for chronic air spaces.
4DefinitiveAdvise against scuba diving unless a specialist diving and thoracic assessment confirms an accepted definitive strategy; give urgent return symptoms in writing.

Key medicines and prescribing safety4 treatments · regimens, roles and cautions

Corrects hypoxaemia while the pleural air is treated and reserve recovers.

Controlled oxygen

Titrate to the BTS target saturation; in COPD or another hypercapnic-risk state use the lower target pending blood gases unless critically hypoxaemic.

Do not withhold oxygen in critical hypoxaemia, but repeat gases after adjustment when CO2 retention is possible. Oxygen alone is not definitive treatment for a clinically important SSP.

Controls pleuritic and drain pain to permit ventilation, coughing and mobilisation.

Multimodal analgesia

Use regular non-opioid treatment and carefully titrated opioid rescue according to frailty, renal function, bleeding risk and respiratory status.

Avoid respiratory depression and oversedation. Sudden severe pain after drainage can indicate malposition, re-expansion stress or non-expandable lung and warrants review.

Reduces pneumothorax recurrence and improves the underlying smoking-related lung disease.

Smoking-cessation pharmacotherapy

Offer a licensed nicotine-replacement or non-nicotine option with behavioural support using current NICE guidance and the BNF.

Select for pregnancy, renal function, mental-health history, interactions and preference. A brief warning without treatment support is inadequate.

Creates pleural symphysis to reduce recurrent pneumothorax risk.

Chemical pleurodesis agent

Administer only through the specialist pleural service using the current local protocol when surgery is unsuitable and recurrence prevention is appropriate.

Discuss lower effectiveness than some surgical approaches, pain, fever and rare systemic complications. Confirm lung apposition and use an approved graded preparation.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Tension physiology

Continuing air entry raises pleural pressure, impairs venous return and can cause obstructive shock, especially during positive-pressure ventilation.

Acute respiratory failure

Loss of limited functioning lung can cause severe hypoxaemia, hypercapnia and exhaustion despite a modest radiographic size.

Persistent air leak

A diseased visceral pleural defect may remain open, prolonging drainage and prompting thoracic specialist intervention, adding morbidity beyond the initial pulmonary disorder.

Recurrence

Underlying structural disease remains after re-expansion, so repeat ipsilateral or contralateral events are frequent and may justify recurrence prevention.

Pleural infection

Prolonged drainage and bronchopleural communication increase infection risk and can create empyema, particularly when baseline cardiopulmonary reserve is limited.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Monitor respiratory rate, work of breathing, saturation, oxygen device, pulse, blood pressure and consciousness closely after presentation and intervention.
Inspect drain fixation, tubing, underwater seal or valve, bubbling, swinging, subcutaneous emphysema and pain every shift.
Repeat blood gas after oxygen changes or deterioration in anyone at risk of hypercapnic respiratory failure.
Use serial imaging according to clinical change and the pleural pathway, especially after drain insertion and before removal.
Document air-leak duration and seek early thoracic review when it persists rather than repeatedly resetting the clock.
Before discharge confirm radiographic status, follow-up ownership, smoking treatment, air-travel and diving advice, and written red flags.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Small image, big physiology

In fibrotic lung or severe COPD, a narrow pleural air rim may remove enough functioning lung to cause major hypoxaemia. Treat the patient’s reserve, not only the measurement.

Bullae make blind drainage dangerous

When a stable patient with emphysema has an atypical lucency and no clear pleural line, CT can prevent placement of a drain into a giant bulla.

Tension is not radiographic size

Positive intrapleural pressure causing impaired venous return defines the emergency. A relatively small pneumothorax under positive-pressure ventilation can create tension.

Bubbling means a communication

Clamping a bubbling drain can recreate tension. First check connections and patient physiology, then involve the pleural team for leak strategy.

Travel advice needs an image date

The BTS interval begins after full radiographic resolution, not after symptoms settle or the drain is removed.

11Common pitfallsFrequent interpretation and management errors.

01
Waiting for radiography before decompressing tension physiology.
02
Applying a primary-pneumothorax conservative pathway to severe secondary disease without considering reserve.
03
Inserting a drain into a giant bulla because CT was omitted despite diagnostic uncertainty.
04
Clamping a bubbling drain or applying suction reflexively.
05
Delaying thoracic-surgical discussion during a persistent air leak.
06
Discharging without recurrence, smoking, air-travel and diving counselling.
07
Using oxygen alone as definitive treatment for a symptomatic clinically important SSP.