Pleural diseases

Question 1

What are different causes of pleural effusions?

Answer 1

• Increased hydrostatic pressure
• Decreased plasma oncotic pressure
• Increased vascular or pleural permeability (inflammation)
• Increased fluid production (Infection)
• Lymphatic capacity can increase 30x if required

Question 2

What should be done if suspected pleural effusion in a severely dyspnoeic animal?

Answer 2

• Radiographs may stress animal excessively
• Standing ultrasound minimally invasive and rapid; readily detects fluid
• With animal in sternal recumbency, under gentle restraint, receiving oxygen, can do “blind” thoracocentesis (or use ultrasound guidance).
• Use e.g. 21G 1 inch Butterfly catheter, with 3-way tap (or one-way valve) and syringe; 7 – 8th ICS, costochondral junction.
• If +ve tap, continue to drain (therapeutic) (submit samples for analysis).
• Thoracocentesis is life-saving in severe pleural effusions.

Question 3

What can be done quickly and good at detecting fluid?

Answer 3

• Ultrasonography

Question 4

What does transudate look like? + possible causes?

Answer 4

• Clear / watery
• Protein <25g/L
• Cells <1.5 x10 (9)/L
• Causes = hypoalbuminaemia

Question 5

What does modified transudate look like? + possible causes?

Answer 5

• Straw coloured, serosanguinous, slightly viscous
• Protein >25g/L
• Cells <5 x10 (9)/L
• Causes = Right sided / biventricular CHF, Diaphragmatic rupture, neoplasia

Question 6

What does exudate look like? + possible causes?

Answer 6

• Blood = trauma, neoplasia, coagulopathy
• Non-septic inflammation - viscous, straw coloured
  = lobe torsion, chronic chylothorax, neoplasia
• Septic inflammation - viscous, turbid, purulent
  = Rupture oes, FB, pyothorax, fungal infection
• Chylous - milky
  = idiopathic, CHF, obstruction, trauma, lobe torsion

*Protein >30g/L
* Cells >5 x10 (9)/L

Question 7

How would you treat pleural effusions after thoracocentesis?

Answer 7

• If due to pericardial effusion, need to rapidly carry out pericardiocentesis
• If due to congestive heart failure, treat as CHF
  – CHF most common reason for pleural effusion in cats.
• If due to hypoproteinaemia, investigate and treat the underlying condition

Question 8

With pyothorax, what should be done?

Answer 8

• Submit material for culture + sensitivity - then base antibiotics on results
• Initially start broad spectrum - potentiated amoxycillins, metronidazole, fluoroquinoloes
• Insert chest drain when stable
• Daily thoracic lavage

Question 9

How would you treat chylothorax after thoracocentesis?

Answer 9

• Treat underlying cause (e.g. CHF)
• Feed low fat diet (high CHO). (reduces chyle prod’n and alters character)
• Add medium chain triglycerides to diet ?
• Rutin (20 – 50 mg/kg q. 8 hours) (may reduce chyle production)
• Almost all cases require surgical management

Question 10

What should always be done post drainage?

Answer 10

• Take radiographs