Resp21 - Pneumothorax & Pleural Effusion

Question 1

3 features of a simple pneumothorax

Definition
Origin of Air x3
Primary Spontaneous Pneumothorax

Answer 1

1.) Definition - the presence of air between the visceral and parietal pleura

2. ) Origin of Air - lungs (common), chest wall or both
   - lung: primary spontaneous or secondary
   - chest wall: trauma, iatrogenic
   - both: trauma e.g. stabbing
3. ) Primary Spontaneous Pneumothorax - often due to a small sub-pleural bleb or bulla that bursts allowing air into the air cavity
   - common in young, tall, thin males and smokers
   - patients have no lung disease or thoracic trauma

Question 2

3 causes of secondary pneumothorax

Underlying Lung Disease x6
Trauma x2
Iatrogenic x2

Answer 2

1. ) Underlying Lung Disease
   - asthma and COPD: air against obstruction increases pressure –> break through viscera
   - others: bronchiectasis, CF, lung cancer, pulmonary infections (pneumonia, TB)
2. ) Trauma - fractured rib or chest trauma
   - fractured rib: puncture the visceral pleura
   - chest trauma: severe blunt or mild sharp can puncture both the visceral and parietal pleura
3. ) Iatrogenic - diagnostic or therapeutic procedure e.g:
   - high pressure ventilation
   - insertion of central lines or pacemakers

Question 3

Signs and symptoms of a simple pneumothorax

History x4
Examination x4
CXR x3

Answer 3

1. ) History - sudden onset, pleuritic chest pain, SOB
   - history of lung disease or trauma
2. ) Examination
   - reduced chest movement on affected side
   - hyper-resonant on affected side
   - reduced/absent breath sounds due to less air movement (air is just there but doesn’t move)
   - reduced vocal resonance
3. ) CXR
   - hyperlucent on affected side due to more air
   - absent lung markings on affected side
   - edge of collapsed lung is visible on affected side

Question 4

3 features of a tension pneumothorax

Definition
Mechanism
Mechanical Shock

Answer 4

1.) Definition - any pneumothorax causing mediastinal shift and cardiovascular collapse (shock)

2. ) Mechanism - air enters the pleural cavity on inspiration but cannot escape on expiration
   - due to a flap that closes on expiration
3. ) Mechanical Shock - haemodynamic shock
   - mediastinal shift compresses the normal lung
   - increased intrapleural pressure is higher than atm pressure for majority of the respiratory cycle so compression of the heart
   - venous return is impaired so cardiac output drops

Question 5

Signs and symptoms of a tension pneumothorax

Symptoms x3
Signs x3
Examination
CXR

Answer 5

1.) Symptoms - fatigue, severe distress and SOB, pleuritic chest pain

2. ) Signs - tachycardia and tachypnoea
   - displaced apex beat due to mediastinal shift
3. ) Examination - similar to simple but more severe
   - hyper-resonant percussion, absent breath sounds
4. ) CXR - similar to simple pneumothorax but:
   - mediastinal shift, displaced heart

Question 6

3 types of treatment for a pneumothorax

Small (simple) Pneumothorax
Large (simple) Pneumothorax
Tension Pneumothorax

Answer 6

1.) Small Pneumothorax - needle aspiration

2. ) Large Pneumothorax - chest drainage
   - inserted into 5th ICS, mid-axillary line
   - just above 6th rib to avoid neurovascular bundle
   - chest drain is removed once lung is fully expanded
3. ) Tension Pneumothorax - emergency needle decompression of the chest
   - insert cannula into the 2nd ICS in mid-clavicular line
   - chest drain replaces cannula when patient is stable

Question 7

3 features of a pleural effusion

Definition
Production and Absorption of Pleural Fluid
Types of Fluid x3

Answer 7

1. ) Definition - excess of fluid in the pleural cavity
   - imbalance in rate of fluid production and absorption
2. ) Production and Absorption of Pleural Fluid
   - 2400ml of fluid produced each day by parietal pleura
   - this is normally absorbed by the lymphatics
   - pleural effusion occurs due to overproduction or under absorption of pleural fluid
3. ) Types of Fluid - blood, lymph, pus
   - blood: haemothorax, due to trauma
   - lymph: chylothorax, leak from lymphatic duct (trauma)
   - pus: empyema, often due to pneumonia

Question 8

transudate vs exudate pleural effusion

Transudate
Exudate (inc 3 causes)
Light’s Criteria

Answer 8

1. ) Transudate - increased formation of pleural fluid
   - more likely to cause bilateral pleural effusions because the causes are often more systemic
2. ) Exudate - increased capillary permeability due to inflammation causes leakage of proteins (exudate)
   - causes: infection (pneumonia, TB), cancer
   - cancer may also block lymphatic drainage
   - PE –> pulmonary infarction
3. ) Light’s Criteria - determines if transudate or exudate
   - pleural:serum protein <0.5 = transudate
   - pleural:serum LDH < 0.6

Question 9

Diagnosis of a pleural effusion

History x2
Examination x4
Chest X-Ray x3
CT Scan
Diagnostic Aspiration

Answer 9

1. ) History - gradual onset of SOB, pleuritic chest pain
   - features of causative disease
2. ) Examination
   - reduced chest movement on affected side
   - stony dull percussion on affected side
   - reduced/absent breath sounds
   - reduced vocal resonance
3. ) CXR - fluid collects in most dependant part so opacity is often in the lower zone when standing upright
   - cannot see outline of diaphragm (silhouette sign)
   - meniscus in upper border

4.) CT Scan - useful to detect underlying pathology and confirm pleural effusion

5. ) Diagnostic Aspiration
   - check protein content and LDH levels
   - gram-stain, culture, cytology

Question 10

3 treatment methods for a pleural effusion

Chest Aspiration
Indwelling Pleural Catheter
Pleurodesis

Answer 10

1. ) Treat Underlying Condition
   - chest aspiration for very symptomatic patients
2. ) Indwelling Pleural Catheter - for recurrent effusions
   - used for intermittent drainage
3. ) Pleurodesis - obliteration of the pleural space
   - introduce Talc into pleural space after draining
   - visceral and parietal pleural to become adherent

Question 11

4 causes of transudative pleural effusion

Answer 11

1. ) Congestive Heart Failure - most common cause
   - less reabsorption due to increased pressure in capillary HP in the venous end
2. ) Hypoproteinaemia - reduced colloid oncotic pressure leads to increased production and reduced absorption
   - nephrotic syndrome: protein loss in urine
   - liver failure: reduced protein synthesis
3. ) Liver Cirrhosis - causes pulmonary hypertension
   - increased production of pleural fluid
4. ) Pulmonary Embolism - pulmonary ischaemia –> release of vasoactive cytokines –> rise in interstitial fluid
   - mainly exudative but can also can cause transudative