Chylothorax and Pyothorax Flashcards
Define chylothoax
The failure of the intestinal lymph to drain normally via the thoracic duct into the venous circulation
What is the most common underlying pathophysiology of a chylothorax?
Idiopathic
What is the success rate of surgery in chylothorax?
40-90%
The thoracic duct returns lymph to the venous circulation from all regions of the body except… (3)
Right thoracic limb, shoulder and cervical regions.
Where does the thoracic duct begin?
Sub lumbar region
Where does the thoracic duct terminate? (2)
Left external jugular vein
Jugulosubclavian angle.
Where is the thoracic duct located in dogs?
Caudal thorax, dorsolateral aorta on RIGHT side
Where is the thoracic duct located in cats?
Caudal thorax, dorsolateral aorta on LEFT side
What are the reported causes of a chylothorax? (9)
-Idiopathic
-Mediastinal or heart-based masses (usually neoplastic)
-Jugular vein/cranial vena cava thrombosis
-Diaphragmatic hernia
-Pericardial effusion
-Congenital abnormalities
-Lung lobe torsions
-Obstruction of cranial mediastinal veins
-Thoracic duct trauma.
What causes the chylothorax?
Increases cranial vena cava hydrostatic pressure, by causing obstruction of the lymphaticovenous junctions and subsequent lymphangiectasia.
Where trauma is the cause of a chylothorax, how do these heal?
Spontaneously
Which dog breed is pre disposed to chylo thorax?
Afghan hound
Which cat breed is pre disposed to a chylo thorax?
Siamese
What are the clinical signs of a chylothorax associated with? What is the common sign if chronic?
- Pleural effusion (e.g., tachypnoea, dyspnoea, lethargy, cough, restrictive breathing pattern etc.).
- Emaciated
What is seen on xrays of a chylothorax?
Pleural effusion
What does a chylothorax yield on thoracocentesis?
Milky coloured fluid
How is a chylothorax definitvely diagnosed?
Comparing triglyceride levels in paired pleural and serum samples
In chyle, serum triglycerides are higher and cholesterol lower compared with serum.
What is the fluid type of a chylothorax?
Modified transudate protein >2.5 g/dL.
What is seen on cytology with a chylothorax?
Initially, lymphocytes and non-degenerate neutrophils predominate (6000-7000 nucleated cells/ul). Later, degenerate neutrophils predominate.
What stain is used for a chylotorax? What does it detect?
Sudan black - chylomicrons
How does the ether clearance test diagnose a chylothorax?
Chylous fluid will clear when potassium hydroxide and ether are added to it.
How is a definitive diagnosis made of a chylothorax?
Lymphangiography immediately before thoracic CT (or, less commonly, radiography), performed by injecting iohexol via ultrasound guidance into the popliteal or mesenteric lymph nodes
How can a chylothorax be medically managed?
Low-fat diet and rutin Intermittent thoracocentesis may be required.
How does changing the diet help a chylothorax?
Low fat diet and rutin - to reduce chylous effusion by decreasing leakage of the lymphatics, increasing protein removal and increasing macrophage number and phagocytosis.
What are the surgical options for a chylothorax? (8)
-Thoracic duct ligation
-Pericardectomy
-Thoracic duct glue embolisation
-Thoracoscopic thoracic duct ligation
-Pleuroperitoneal drainage
-Pleural omentalisation
-Cysterna chyli ablation
-Percutaneous drainage (e.g., Pleural Port).
What is the most common surgical treatment of a chylothorax? How does this work?
Identification and ligation of all the branches of the thoracic duct, which encourages formation of new anastomoses between the lymphatic and venous systems.
What concurrent surgery should be done at the same time as a thoracic duct ligation for chylothorax treatment? why?
Pericardectomy is recommended to decrease right sided pressures, which facilitates anastomotic development.
What surgical approach should be taken for a thoracic duct ligation and pericardectomy for chylothorax treatment? (2)
Open or thoracoscopically