Pleural Effusion & Pneumothorax

Question 1

What is a Pleural Effusion?

Answer 1

Pleural effusion is the presence of fluid between visceral and parietal pleura.

Question 2

Discuss the basic presentation & investigation of pleural effusions

Answer 2

Asymptomatic until >500mL of fluid is present.
* Breathlessness
* dry cough
* pleuritic pain
* B symptoms + fever can be present depending on underlying cause.

Signs on examination of the affected side
* decreased expansion
* stony dull percussion note
* reduced or absent breath sounds
* reduced vocal resonance
Bronchial breathing is often present above an effusion and a pleural rub may be heard.

IX
* CXR - basal opacity obstructing hemidiagphragm
* Thoracic Ultrasound
* CT scan - undiagnosed or unresolved exudate

Question 3

What is Lights Criteria?

Answer 3

Light’s criteria are more accurate for the diagnosis of exudative effusions.
The fluid is considered an exudate if any of the following are present:
* The ratio of pleural fluid to serum protein is greater than 0.5
* The ratio of pleural fluid to serum LDH is greater than 0.6
* The pleural fluid LDH value is greater than two-thirds of the upper limit of the normal serum value

If a patient is thought to have a transudative pleural effusion but the Light’s Criteria suggest an exudate, the serum–pleural fluid protein gradient should be examined.

Question 4

What is an exudate pleural effusion?

Answer 4

Exudate pleural effusions occur when local factors influencing pleural fluid formation and reabsorption are altered through injury/inflammation.
Protein >30 g/L (in patients with a normal serum protein level)

Question 5

What causes an exudate pleural effusion?

Answer 5

• Infection
• Malignancy
• Pulmonary Embolism
• Pulmonary infarction
• Trauma
• Autoimmune - SLE & RA

Question 6

What is a transudate pleural effusion?

Answer 6

Transudative pleural effusions are defined as effusions that are caused by factors that alter hydrostatic pressure, pleural permeability, and oncotic pressure.
Protein <30 g/L (in patients with a normal serum protein level)

Question 7

What causes a transudate pleural effusion?

Answer 7

• Congestive heart failure
• Liver cirrhosis (Liver failure)
• Severe hypoalbuminemia
• Nephrotic syndrome (Chronic Kidney Disease)

Question 8

Discuss the treatment of an exudate pleural effusion

Answer 8

Small & Asymptomatic - watch & wait
larger & symptomatic - chest drain or pleural fluid aspiration

If malignant effusion is asymptomatic, it should be observed and treated only if symptoms arise

Question 9

Discuss the treatment of a transudate pleural effusion

Answer 9

This should focus on the underlying disease and doesn’t routinely require drainage
Therapeutic aspiration can help with symptom relief in patients with very poor life expectancy.

Question 10

What is Empyema?

Answer 10

Empyema is pus within the pleural space
3 stages;
1. parapneumonic effusion
2. fibrinopurulent stage
3. a pleural peel is formed

Clinical features are similar to that of pneumonia
Anaerobic empyema may present insidiously with only weight loss and decreased appetite especially in the elderly
Treatment is with antibiotics that penetrate the pleural space (commonly penicillin and B-lactamase inhibitors).

Question 11

What is Chylothorax?

Answer 11

Chylothorax is an accumulation of lymph in the pleural space

Commonest causes are rupture or obstruction of the thoracic duct caused by trauma or neoplasm.
A latent period of 2-10 days occurs between injury and onset, pleural fluid is high in lipid and has milky appearance.
If suspected, fluid should be tested for cholesterol crystals, chylomicrons and triglyceride and cholesterol levels to help differentiate from a pseudochylothorax. Levels of triglyceride and chylomicrons will be high in true chylothorax whilst levels of cholesterol are high in pseudochylothorax.

Question 12

What is a pneumothorax?

Answer 12

Pneumothorax is a condition characterized by the accumulation of air in the pleural space, resulting in the partial or complete collapse of the affected lung

Question 13

Discuss the basic epidemiology of pneumothorax

Answer 13

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

Question 14

Discuss the causes of a primary pneumothorax

Answer 14

• 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

Question 15

Discuss the causes of a secondary pneumothorax

Answer 15

• Chronic obstructive pulmonary disease (70% of secondary pneumothorax): rupture of air bulla (air-filled space in lungs, caused by emphysematous destruction of lung tissue)
• Asthma: rupture of air bulla or subpleural air bleb, though the mechanism is still poorly understood.
• Cystic fibrosis: endobronchial obstruction causing increased pressure in the alveoli, leading to alveolar rupture
• 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)

Question 16

Discuss the causes of a tension pneumothorax

Answer 16

• Penetrating/blunt trauma
• Mechanical ventilation or non-invasive ventilation (NIV)
• Conversion of simple pneumothorax to tension pneumothorax

Question 17

Discuss the pathophysiology of pneumothorax

Answer 17

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 off.

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

Question 18

Discuss the basic presentation & investigation of pneumothorax

Answer 18

Symptoms tend to come on suddenly:
* dyspnoea
* chest pain: often pleuritic
Signs
* hyper-resonant lung percussion
* reduced breath sounds
* reduced lung expansion
* tachypnoea
* tachycardia

Question 19

Discuss the basic management of pneumothorax

Answer 19

The first step is assessing whether the patient is symptomatic
* the BTS define minimal symptoms as ‘no significant pain or breathlessness and no physiological compromise’
* no or minimal symptoms → conservative care, regardless of pneumothorax size
* symptomatic → assess for high-risk characteristics

If a pneumothorax is symptomatic, the next step is assessment for high-risk characteristics;
* haemodynamic compromise (suggesting a tension pneumothorax)
* significant hypoxia
* bilateral pneumothorax
* underlying lung disease
* ≥ 50 years of age with significant smoking history
* haemothorax

if no high-risk characteristics are present, and it is safe to intervene, then there is a
choice of intervention:
* conservative care
* ambulatory device
* needle aspiration

if high-risk characteristics are present, and it is safe to intervene → chest drain

Question 20

How can a pneumothorax be classified?

Answer 20

• Primary spontaneous pneumothorax
• Secondary spontaneous pneumothorax
• traumatic pneumothorax
• Iatrogenic pneumothorax
• Tension pneuomothorax
• Catamenial pneumothorax

Question 21

What is a Primary spontaneous pneumothorax?

Answer 21

Occurs without underlying lung disease, often in tall, thin, young individuals.
PSP is associated with the rupture of subpleural blebs or bullae

Question 22

What is a Secondary spontaneous pneumothorax?

Answer 22

Occurs in patients with pre-existing lung disease, such as COPD, asthma, cystic fibrosis, lung cancer, Pneumocystis pneumonia.
Certain connective tissue diseases such as Marfan’s syndrome are also a risk factor

Question 23

What is a traumatic pneumothorax?

Answer 23

results from penetrating or blunt chest trauma, leading to
lung injury and pleural air accumulation

Question 24

What is an iatrogenic pneumothorax?

Answer 24

occurs as a complication of medical procedures, such as thoracentesis, central venous catheter placement, ventilation, including non-invasive ventilation or lung biopsy.

Question 25

What is a tension pneumothorax?

Answer 25

Tension pneumothorax is a life-threatening condition characterised by the accumulation of air in the pleural space under positive pressure, leading to the collapse of the lung on the affected side and a shift of the mediastinum towards the contralateral side.
This process results in impaired venous return to the heart and subsequent reduction in cardiac output, posing a significant risk of cardiovascular collapse.

Question 26

What is a catamenial pneumothorax?

Answer 26

3-6% of spontaneous pneumothoraces occurring in
menstruating women. It is thought to be caused by endometriosis within the thorax.

Question 27

What is the presentation of a tension pneumothorax?

Answer 27

Symptoms tend to come on suddenly:
* dyspnoea
* chest pain: often pleuritic
Signs
* hyper-resonant lung percussion
* reduced breath sounds
* reduced lung expansion
* tachypnoea
* tachycardia
In tension pneumothorax:
* respiratory distress
* tracheal deviation away from the side of the pneumothorax
* hypotension

Question 28

What is conservative care of a pneumothorax?

Answer 28

patients with a primary spontaneous pneumothorax that is managed conservatively should be reviewed every 2-4 days as an outpatient
patients with a secondary spontaneous pneumothorax that is managed conservatively should be monitored as an inpatient
if stable, follow-up in the outpatients department in 2-4 weeks

Question 29

What is Ambulatory care?

Answer 29

Ambulatory devices typically have a one-way valve and vent to prevent air and fluid return to the pleural space while allowing for controlled escape of air and drainage of fluid

Question 30

What happens in recurrent pneumothorax?

Answer 30

If a patient has a persistent air leak or insufficient lung reexpansion despite chest drain insertion, or the patient has recurrent pneumothoraces, then video-assisted thoracoscopic surgery (VATS) should be considered to allow for mechanical/chemical pleurodesis +/-bullectomy.

Question 31

DIscuss the pathophysiology of a tension pneumothorax

Answer 31

Tension pneumothorax develops when air enters the pleural space and is unable to escape, creating a one-way valve effect
This can be due to a flap of tissue acting as a valve, or a similar mechanism in a traumatic or iatrogenic wound
The continuous accumulation of air leads to increased intrapleural pressure which exceeds atmospheric pressure throughout the respiratory cycle
as intrapleural pressure rises, it exerts several serious effects:
* Lung collapse - the affected lung collapses causing a decrease in functional residual capacity & impaired gas exchange
* Mediastinal shift - the increased pressure pushes the mediastinum to the opposite side compressing the opposite lung further impairing respiratory function
* Impaired venous return - The mediastinal shift and raised intrathoracic pressure compress the great veins reducing venous return to the heart. This diminishes cardiac output and can lead to obstructive shock, characterised by hypotension and tachycardia.
* Reduced Cardiac filling - The direct pressure on the heart, coupled with reduced venous return, impairs both right and left ventricular filling. This can precipitantly lower cardiac output and systemic blood pressure

Question 32

What is the management of a tension pneumothorax?

Answer 32

Decompression of the pleural space
This is initially performed via needle thoracostomy, inserting a cannula into the second intercostal space in the midclavicular line on the affected side
This is followed by the placement of a chest drain (tube thoracostomy) in the safe triangle of the chest to allow continuous drainage of air.