11/14/24, 10\:49 AM Pneumothorax

Pneumothorax

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Pneumothorax\: collection of air in pleural space; primary (no known respiratory disease), secondary (pre-existing
respiratory disease), tension (mediastinal displacement and haemodynamic compromise).
Incidence\: 19 per 100,000 in males, 8 per 100,000 in females; 85% are primary, highest incidence in patients over 65.
Primary pneumothorax causes\: often unknown, rupture of subpleural air bleb.
Secondary pneumothorax causes\: COPD (70%), asthma, cystic
Tension pneumothorax causes\: trauma, mechanical ventilation, conversion of simple pneumothorax.
Pathophysiology\: air moves into pleural space due to pressure gradient, compresses lungs; tension pneumothorax
involves one-way valve, increased intrapleural pressure, mediastinal shift, reduced cardiac output and venous return.
Risk factors\: smoking, tall/thin build, male sex, young age (primary pneumothorax).
Symptoms\: ipsilateral pleuritic chest pain, dyspnoea, cough; small pneumothorax may be asymptomatic.
Clinical
includes tracheal deviation, severe tachycardia, hypotension.
Investigations\: pulse oximetry, lung ultrasound (absence of lung sliding), chest X-ray (visible rim, absence of lung
markings), CT chest (identify small pneumothoraces, causes).
Management\:
Simple pneumothorax\: conservative management, needle aspiration, small-bore chest drain if needed.
Tension pneumothorax\: emergency decompression with large-bore cannula, followed by chest drain insertion.
Follow-up\: outpatient respiratory follow-up, repeat chest X-ray in 2-4 weeks, advice against
open thoracotomy and pleurectomy or medical pleurodesis for recurrent cases.
Complications\:
Disease-related\: respiratory failure, cardiac arrest, pneumopericardium.
Treatment-related\: pain, re-expansion pulmonary oedema, subcutaneous emphysema.
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A comprehensive topic overview

Introduction

A pneumothorax is a collection of air inside the pleural space, which is the space between the lungs and chest wall
(Figure 1).
A primary pneumothorax occurs in a patient without a known respiratory disease, whereas a secondary pneumothorax
occurs in a patient with pre-existing respiratory disease.
Patients >50 years old and those with a signi
A tension pneumothorax is a severe pneumothorax involving the displacement of mediastinal structures and
haemodynamic compromise.
1
In the UK, the incidence of pneumothorax is 19 per 100,000 in males and 8 per 100,000 in females. 85% of pneumothoraces
are primary, and incidence is highest in patients aged over 65.
2-3
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Figure 1. The pleural space.
4

Aetiology

Causes of primary pneumothorax include\:
Often unknown
May be due to rupture of a subpleural air bleb (found in the pleural space). The bleb itself is caused by alveolar rupture,
which lets air travel through the interlobular septum into the subpleural space.
5
Causes of secondary pneumothorax include\:
Chronic obstructive pulmonary disease (70% of secondary pneumothorax)\: rupture of air bulla (air-
caused by emphysematous destruction of lung tissue).
6-7
Asthma\: rupture of air bulla or subpleural air bleb, though the mechanism is still poorly understood.
8
Cystic \: endobronchial obstruction causing increased pressure in the alveoli, leading to alveolar rupture.
9
Marfan syndrome\: abnormal lung connective tissue leads to increased formation of air bulla (which rupture), and tall
body habitus increases mechanical stress on lung apices (exacerbating bulla rupture).
10
Causes of tension pneumothorax include\:
11
Penetrating/blunt trauma
Mechanical ventilation or non-invasive ventilation (NIV)
Conversion of simple pneumothorax to tension pneumothorax

Pathophysiology

The alveolar and atmospheric pressures are greater than the intrapleural pressure. Therefore, connections between the
alveoli and pleural space, or surrounding atmosphere and pleural space, will lead to air moving down a pressure gradient
into the pleural space.
This increases the intrapleural pressure, potentially compressing the lungs. Air will continue to move into the pleural
space until the pressure gradient equilibrates or the connection into the pleural space seals o
12
In a tension pneumothorax, air enters the pleural space through a one-way valve and is therefore unable to leave the
pleural space. The intrapleural pressure exceeds the atmospheric pressure, leading to collapse of the ipsilateral lung
and a shift of the mediastinum away from the pneumothorax.
In severe cases, the increased intrapleural pressure can compress the heart and surrounding vasculature, reducing
cardiac output and venous return. If untreated, this may lead to cardiac arrest.
1

Risk factors

Risk factors for pneumothorax include\:
Smoking
Tall and thin build
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Male sex
Young age (in primary pneumothorax)

Clinical features

History

A small pneumothorax may be asymptomatic.
13
Typical symptoms of pneumothorax include\:
Ipsilateral pleuritic chest pain
Dyspnoea
Cough
Other important areas to cover in the history include\:
Recent trauma to the chest wall
Smoking history\: quantify in pack-years (1 pack-year equates to smoking 20 cigarettes a day for a whole year)
Family history of pneumothorax

Clinical examination

A full respiratory examination should be performed in suspected cases of pneumothorax.
Typical clinical
Hyper-resonant lung percussion
Reduced breath sounds
Reduced lung expansion
In addition, typical clinical
Tracheal deviation away from the pneumothorax
Severe tachycardia
Hypotension

Di

The presenting complaints of pneumothorax have important di
diagnoses, and the features which di
Table 1. Di
Di
Features di
pneumothorax
Acute asthma exacerbation
Expiratory wheeze
Trial of bronchodilator relieves
symptoms
CXR\: usually normal
Pleural e
Stony dull percussion
Chest pain may ease as e
continues to enlarge, as the visceral
and parietal pleural move apart (and
so there is less rubbing between the
pleura, which is the cause of the
pleuritic chest pain)
14
CXR\: pleural e
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Pulmonary embolism
Myocardial infarction
Unilateral calf swelling/tenderness
(DVT)
Risk factors for PE (e.g. recent
immobility)
CTPA\: pulmonary embolism
Classically described as crushing
chest pain (rather than pleuritic)
Radiates to neck/arm
ECG\: signs of ischaemia (e.g. ST
elevation)

Investigations

Bedside investigations

Relevant bedside investigations include\:
Pulse oximetry
Lung ultrasound\: used in supine trauma patients, for whom a chest X-ray may be di

pleural. This is absent in pneumothorax as there is air separating the visceral pleura from the parietal pleura.
15

Laboratory investigations

Relevant laboratory investigations include\:
Full blood count\: important in trauma cases, as the patient may need a blood transfusion
Clotting screen\: may need to correct coagulopathy (such as INR >1.5) or hold anticoagulants/antiplatelets, although this
may not be possible in an emergency procedure.
16
Arterial blood gas (ABG)\: the most common respiratory alkalosis secondary to hyperventilation, but it may
demonstrate type 1 respiratory failure in severe cases.

Imaging investigations

Relevant imaging investigations include\:
Chest X-ray (Figures 2 and 3)\: visible rim between the lung margin and chest wall, with an absence of lung markings. The
size of the pneumothorax is measured at the level of the hilum. Whilst management used to be predominantly guided
by pneumothorax size, this is no longer the case.
17
CT chest (Figure 4)\: may be used to identify small pneumothoraces missed by chest X-ray. Also, can help to identify the
cause of the pneumothorax (can show air bulla or emphysematous changes).
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Figure 2. Chest X-ray of a simple pneumothorax.
18
Figure 3. Chest X-ray of a tension pneumothorax.
19
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Figure 4. CT chest showing a pneumothorax.
20

Management

For more information on the emergency management of pneumothorax, see the Geeky Medics guide to the acute
management of pneumothorax using an ABCDE approach.

Simple (non-tension) spontaneous pneumothorax

There have been signi
management guided by pneumothorax size. Management is now more individualised, guided by symptoms (e.g.,
breathlessness and chest pain) and the degree of physiological compromise.
17
Figure 5 outlines the management of a spontaneous pneumothorax.
If needle aspiration fails and there are high-risk characteristics in a symptomatic patient, a small-bore chest drain (\<14
French) is required.
F i g u r e 5 . B T S 2 0 2 3 S p o n t a n e o u s P n e u m o t h o r a x G u i d e l i n e s .
1 7
Chest drain insertion
If a chest drain is inserted, look out for\:
Swinging\: the
intrathoracic pressure during inspiration when the diaphragm descends).
Bubbling\: the
eventually). The persistence of bubbling for >48 hours may indicate an air leak, which is a connection between the
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bronchial tree and pleural space (also known as a bronchopleural 21
thoracic surgeon.
This may need to be discussed with a

Tension pneumothorax

Management of tension pneumothorax should include\:
1. Emergency decompression\: insert a large-bore cannula (e.g. orange 14G or grey 16G) into the 2 nd
the mid-clavicular line
intercostal space, along
2. Chest drain insertion immediately after emergency decompression

Follow up

In general, patients should have outpatient respiratory follow-up and a repeat chest X-ray in 2-4 weeks to assess for the
resolution of pneumothorax. They should be advised not to
A recurrent/di
removed, and so the lung sticks to the inner surface of the chest wall, preventing pneumothorax recurrence.
22
Medical pleurodesis may be needed in patients un
talc), which obliterates the space between the visceral and parietal pleura, preventing pneumothorax recurrence.
23

Complications

Disease-related complications of pneumothorax include\:
Respiratory failure
Cardiac arrest (in tension pneumothorax)
Pneumopericardium (air in the pericardial space)
Treatment-related complications of pneumothorax include\:
Pain
Re-expansion pulmonary oedema\: typically occurs after drainage of a large pneumothorax that has been present for >72
hours. Rapid re-expansion of a previously collapsed lung can lead to increased permeability of pulmonary vessels, for
unknown reasons. 24
This leads to
Subcutaneous emphysema\: when the chest drain is inserted into the subcutaneous tissue, rather than the pleural space

References

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Risk factors

Reviewer

Clinical features
Dr Neeraj Shah
Di
Specialist registrar in Respiratory Medicine
Investigations
Management
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