Pneumothorax

Question 1

What is a Pneumothorax?

Answer 1

Pneumothorax= the partial or complete collapse of a lung due to the build up of gas in the pleural space.

Question 2

Pneumothorax: Aetiology

Pneumothoraces are classified according to their aetiology.

Answer 2

• Primary spontaneous pneumothorax - occurs without cause. The symptoms are often mild, regardless of size, and some patients will present after more than 2 days of symptoms.
• Secondary pneumothorax - occurs as a result of trauma, lung pathology (eg. infection, asthma, carcinoma, Marfan’s), or iatrogenic causes (eg. lung biopsy, mechanical ventilation or NIV or central line insertion) or if >50 age with significant smoking history. The symptoms vary (e.g. fever, weight loss, night sweats) and are often more severe because lung function may already be compromised.
• Tension pneumothorax - occurs when the lung defect acts as a one-way valve that lets air into the pleural space, on inspiration, but not out on expiration. The gradual increase in intrathoracic pressure can cause mediastinal shift. This can lead to haemodynamic compromise and cardiorespiratory arrest. This makes it a medical emergency. All types of pneumothorax can develop into a tension pneumothorax.

Question 3

Pneumothorax: Risk Factors

Answer 3

• Smoking
• Tall and thin build
• Male sex
• Young age (in primary pneumothorax)
• Family History (?)

Question 4

Pneumothorax: Symptoms

Answer 4

• Asymptomatic - small pneumothorax
• Ipsilateral pleuritic chest pain
• Dyspnoea (+ tachyponea)
• Cough
• Acute onset

Question 5

Pneumothorax: Respiratory Examination Signs

Answer 5

• A small pneumothorax can be impossible to identify on clinical examination.
• Typical clinical findings in pneumothorax include (on the same side as the pneumothorax):
  
  • Reduced lung expansion
  • Hyper-resonant lung percussion
  • Reduced breath sounds (smaller lungs means less air is entering)
• Additional typicalclinical findings in tension pneumothoraxinclude:
  
  • Tracheal deviation away from the pneumothorax
  • Severe tachycardia
  • Hypotension
  • Distended neck veins (due to increased central venous pressure). Therefore, Raised jugular venous pressure (JVP) also (an indirect measure of CVP).
  • Hypoxic (low levels of oxygen in your body tissues)

Question 6

Pneumothorax: Investigations

Answer 6

• Bedside investigations:
  
  • Pulse oximetry: Low PaO2.
  • Lung ultrasound: used in supine trauma patients, for whom a chest X-ray may be difficult to obtain. The characteristic finding is an absence of lung sliding between the visceral pleura and parietal pleura.
• Laboratory investigations
  
  • FBC: to exclude anaemia and infection. Also, patient may need ablood transfusion
  • Clotting screen: may need to correct coagulopathy (such as INR >1.5 or platelets <50), although this may not be possible in tension pneumothorax. Also, clotting abnormalities might alter management (e.g. decision on inserting a chest drain).
  • ABG: the most common finding isrespiratory alkalosis secondary to hyperventilation, but it may demonstrate type 1 respiratory failure in severe cases.
  • U&Es
  • CRP: to screen for inflammation (eg. pneumonia)
  • ECGs: to exclude cardiac causesof chest pain but should not delay initial management. Normal in pneumothorax.
• Imaging investigations
  
  • Erect Chest X-Ray:
    
    • Clear area with no lung markings between visceral and parietal pleura. >2cm is a “large” pneumothorax. Measured between both pleura at the level of the hilum.
    • Flat or inverted diaphragm
    • Deep sulcus sign (a deep costophrenic angle)
    • Mediastinal deviation (tension)
    • Can also exclude other respiratory diagnoses (e.g. pneumonia, pulmonary oedema)
  • CT chest: used to identify small pneumothoraces missed by chest X-ray, accurately assess the size of a pneumothorax and identify the cause of the pneumothorax (can show air bulla or emphysematous changes).

Question 7

Pneumothorax: Non-Surgical Management

Answer 7

Primary Spontaneous Pneumothorax

• No shortness of breath + non-large (<2cm rim of air on CXR) pneumothorax:
  
  • No treatment + follow-up in 2-4 week. Should spontaneously resolve
• Shortness of breath +/- large pneumothorax:
  
  • Needle Aspiration + reassessment. Size should decrease to <2cm + improved breathing
  • If aspiration fails twice, complete a chest drain + admit
• Bilateral pneumothoraces and haemodynamically unstable patients require a chest drain.

Secondary Spontaneous Pneumothorax

• No shortness of breath + <1cm pneumothorax:
  
  • Admit + 24hr observation + high-flow O2 (unless risk of type 2 respiratory failure eg. COPD)
• No shortness of breath + 1-2cm pneumothorax:
  
  • Aspiration + reassessment. Size should decrease to <1cm
    
    • Admit + 24hr observation + high-flow O2 (unless risk of type 2 respiratory failure eg. COPD)
  • If aspiration fails twice, complete a chest drain + admit
• Bilateral pneumothoraces and haemodynamically unstable patients require a chest drain.

Tension Pneumothorax

If a tension pneumothorax is suspected, do not wait for any investigations. A chest drain is required for definitive management once the pressure is relieved with a cannula.

• Management
  1. Emergency needle decompression/aspiration/thoracentesis: insert a large-bore cannula (e.g. orange 14G or grey 16G or 16-18G) into the2ndintercostal space, along themid-clavicular line
  
  • Advanced Traumatic Life Support (ATLS) 2018 recommend using the “fourth or fifth intercostal space, anterior to the midaxillary line” for adults as chest wall thickness is smaller here than in the second intercostal space.
    
    2. Chest drain insertion immediately after emergency decompression

Question 8

How is a Chest Drain performed?

Answer 8

• Chest drains are inserted in the “triangle of safety”. This triangle is formed by the:
  
  • 5th intercostal space(or the inferior nipple line)
  • Midaxillary line(or the lateral edge of thelatissimus dorsi)
  • Anterior axillary line(or the lateral edge of thepectoralis major)
  • The needle is inserted just above the rib to avoid theneurovascular bundlethat runs just below the rib. Once the chest drain is inserted, obtain a chest x-ray to check the positioning.
• The external end of the drain is placed underwater, creating a seal. This allows air to escape the chest cavity and bubble through the water, and also prevents air from re-entering the drain and chest.
• When a chest drain is inserted successfully, look out for:
  
  • Swinging: the water in the chest drain will rise and fall with respiration due to pressure changes in the chest. swinging should reduce as the pneumothorax resolves.
  • Bubbling: the water in the chest drain bubbles when the pneumothorax is initially drained (this should stop eventually). If the water continues to bubble for >48 hours, there may be an air leak, which is a connection between the bronchial tree and pleural space (also known as a bronchopleural fistula).This may need to be discussed with a thoracic surgeon.
• If there is no swinging or bubbling, there may be a problem with the drain, such as:
  
  • Blocked or kinked tube
  • Incorrect position in the chest
  • Not correctly connected to the bottle
• If the chest drain is successful, there will bere-inflationof the lung on a repeat chest x-ray,.
• Two key complications of chest drains are:
  
  • Air leaksaround the drain site (indicated by persistent bubbling of fluid >48hrs, particularly on coughing)
  • Surgical emphysema (aka.subcutaneous emphysema) is when air collects in the subcutaneous tissue. chest drain is inserted into the subcutaneous tissue, rather than the pleural space

Question 9

Pneumothorax: Surgical Management

Answer 9

Patients may require surgical interventions when:

• A chest drain fails to correct the pneumothorax
• There is a persistent air leak in the drain
• The pneumothorax reoccurs (recurrent pneumothorax)

Video-assisted thoracoscopic surgery(VATS) can be used to correct a pneumothorax.

The surgical options are:

• Abrasive pleurodesis(using direct physical irritation of the pleura)
• Chemical pleurodesis(using chemicals, such astalc powder, to irritate the pleura)
• Pleurectomy(removal of the pleura)

Pleurodesisinvolves creating an inflammatory reaction in the pleural lining so the pleura sticks together and the pleural space becomes sealed. This prevents further pneumothoraces from developing.

• A recurrent/difficult pneumothorax may need anopen thoracotomy and pleurectomy. The parietal pleura is usually removed, and so the lung sticks to the inner surface of the chest wall, preventing pneumothorax recurrence.
• Medicalpleurodesismay be needed in patients unfit for surgery. This involves inserting a chemical (such as tetracycline or talc), whichobliterates the spacebetween the visceral and parietal pleura, preventing pneumothorax recurrence.

Question 10

Pneumothorax: Follow-up

Answer 10

In general, patients should have outpatient respiratory follow-up and a repeat chest X-ray in2-4 weeksto assess for the resolution of pneumothorax. They should be advised not to fly until full resolution of the pneumothorax.

Question 11

Pneumothorax: Complications

Answer 11

Disease-related complicationsof pneumothorax include:

• Respiratory failure
• Cardiac arrest (in tension pneumothorax)
• Pneumopericardium (air in the pericardial space)

Treatment-related complicationsof 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.This leads to fluid moving into the lung parenchyma, causing pulmonary oedema.
• Subcutaneous emphysema: when the chest drain is inserted into the subcutaneous tissue, rather than the pleural space

Question 12

Pneumothorax: Differential Diagnoses

Answer 12

Acute asthma exacerbation, Pleural effusion, Pulmonary embolism, Myocardial infarction