Chylothorax and Pleural Effusions SDL

Question 1

What is pleural effusion and what clinical signs does it account for?

Answer 1

• Fluid in between visceral and parietal pleura
• Accounts for muffled heart sounds and inability to breathe when lying in lateral recumbency as well as the dyspnoea and cough

Question 2

What is pulmonary oedema and what would you expect to hear on ascultation?

Answer 2

• Fluid in lungs
• You would expect crackles on cardiac auscultation and the lung fields would not be dull ventrally.
• Pulmonary oedema is often secondary to cardiac disease so you might expect some cardiac abnormalities too

Question 3

What are the different types of pleural effusion?

Answer 3

• Pure transudate
• Modified transudate
• Exudate
• Pyothorax
• Chylothorax

Question 4

What are the features of a pure transudate?

Answer 4

• Protein under 25g/L
• Clear in colour
• Low cellularity

Question 5

What are the features of a modified transudate?

Answer 5

• Moderate cellularity
• Slightly hazy in colour
• Protein 25-40 g/L

Question 6

What are the features of an exudate?

Answer 6

• Typically opaque in colour
• Protein >30g/L
• Moderate to high cell count

Question 7

What are the features of an pyothorax?

Answer 7

• High cell count and smells
• Amber red or yellow in colour
• Protein >35g/L

Question 8

What are the features of an Chylothorax?

Answer 8

• Protein variable
• High cell count
• Creamy +/- pale pink in colour

Question 9

Where should thoracocentesis for pleural effusion be performed?

Answer 9

• The tap is performed at the seventh or eighth intercostal space.
• The needle is inserted just cranial to the rib to avoid the intercostal vessels and nerves.
  
  • If air is being aspirated, the tap should be performed from the mid to the dorsal third of the intercostal space.
  • If fluid is being aspirated, the tap should be performed at the costochondral junction

Question 10

An opaque pink fluid is obtained by thoracocentesis. What type of pleural effusion is this?

Answer 10

Chylothorax

Question 11

What are the causes of a chylothorax?

Answer 11

• Rupture/obstruction of lymphatic flow: neoplasia, traumatic, idiopathic
• Secondary to heart failure (especially in cats)

Question 12

Which tests can you do to confirm a chylothorax, and what results do you expect?

Answer 12

• To diagnose chylothorax you would do radiography, thoracocentesis and submit sample for cytology in EDTA tube
• Fluid to serum triglyceride ratio check; you would expect the effusion fluid to be higher in triglyceride than the serum

Question 13

What are the options for managing pleural effusion?

Answer 13

• Repeated thoracocentesis
  
  • Not ideal if there are several litres of fluid
• Place chest drains
  
  • An ideal first step, drain enough to stablise for a quick general anaesthetic then place chest drains
• Low fat diet and Rutin
  
  • Conservative management for cases where there is not much fluid
• Thoracotomy and thoracic duct ligation
  
  • May need to do this eventually but usually we try medical management first with repeated fluid drainage.

Question 14

What are the benefits of Rutin in managing pleural effusion?

Answer 14

Thought to:

• decrease leakage from blood vessels,
• increase protein removal by lymphatic vessels,
• increase macrophage phagocytosis of chyle,
• increase tissue macrophage numbers
• increase proteolysis and removal of protein from tissues