Respiratory Medicine: Pleural Disease

Question 1

What is dyspnoea?

Answer 1

Difficult or laboured breathing

Question 2

What are the three factors that can result in pleural effusion?

Answer 2

• Rate of pleural fluid production increases
• Rate of drainage is decreased
• Increased vascular permeability

Question 3

What are the two causes of increased fluid production in the pleural space

Answer 3

• Hydrostatic pressure increases- CHF
• Plasma oncotic pressure is decreased- hypoalbuminaemia

This results in transudate ( increased pressure/decreased oncotic)

Exudate- increased vascular perm (protein)

Question 4

What caused a modified transudate in the pleural space?

Answer 4

Chronic transudate results in some pleural inflammation- protein and cell content mildly increase

Question 5

What can cause exudate in the pleura?

Answer 5

• Inflammed/infected pleura
• Neoplasia
• Increases vascular perm
• Coagulpathy- haemothorax
• Chylothorax- ruptured thoracic duct

Question 6

What are the clinical signs of pleural effusions?

Answer 6

• Rapid shallow respirations- progressing to dyspnoea
• Decreased persussion- ventrally especially
• Decreased breath sounds ventrally and muffled heart sounds
• Decreased thoracic compressibility
• CHF- jugular vein distension (can be cranial mediastinal mass)

Question 7

When is thoracocentesis not indicated with a pleural effusion severly compromising resp function?

Answer 7

Possibly: In an active haemorrhage

Question 8

How can effusions be detected?

What should be done after throacocentesis?

Answer 8

Thoracic radiography is non-informative
Brief thoracic ultrasound (T-fast) is sensitive

Effusions should be drained prior to radiography or other investigations

Radiography after thoracocetentesis- identify any pulmonary masses

Question 9

Describe thoracocentesis?

Answer 9

• Usually sternal recumbancy
• Site- avoid heart/liver- US guidance- blind 7/8th intercostal space at costochondral junction
• Surgically prepare the area
• Wear gloves and follow aseptic precautions
• ± sedation, ± local
• Cats- use butterfly catheter (21G)
• Dogs- diagnostic- needle, drainage use large bore (16/14G) IV catheter, three way tap and syrinfe and extension tubing
• Store samples in plain and EDTA tubes

Question 10

Describe transudates, modified transudates and exudated?

Answer 10

• Transudate- uncommon, very clear, cell count <1.5 x 10 ^9
• Modified transudates- most common, CHF usually- straw coloured, TP > 25g/l, cell count <5 x 10^9
• Exudates- classified to their types

Question 11

What are the two primary causes of pyothorax?

Answer 11

• Penetrating injuries
• Secondary to migrating vegetable matter

Question 12

How should a pyothorax be treated?

Answer 12

• Antibiotic selection based on sensitivity results
• Bilateral chest drains and thoracic lavage carried out (20ml/kg warm saline) until clear

Question 13

1. When does chyle not appear very milky in appearance?
2. What does cytology of chyle show?

Answer 13

1. Patient is on a low fat diet
2. High cellularity, mainly small lymphocytes

Question 14

What my chylothorax be associated with?

Answer 14

• Right sided/biventricular CHF
• Any lesions resulting in obsctruction/raised vena cava pressures
• Rupture of thoracic duct
• Lung lobe torsions
• Idiopathic
• Constrictive pericardial disease

Question 15

What does chylothorax result in?

Answer 15

• Stimulates inflammatory response
• May resilt in fibrosing pleuritis

Question 16

What is the treatment and managment of chylothorax?

Answer 16

• Treatment is addresed at the underlying cause
• Managment low fat diet with added medium chain triglycerides
• Best results- surgical managment (thoracic duct ligation)

Question 17

1. What are the possible causes of pneumothorax?
2. What are the clinical signs?
3. What is the treatment?

Answer 17

1. Trauma, iatrogenic, rupture of lung bullae
2. Restrictive breathing, percussion resonance increased, normal heart/lung
3. Thoracocentesis