Chapter 105: Thoracic Cavity Flashcards
What is normal plural fluid volume in dogs and cats?
- Dog - 0.1ml/kg
- Cats: 0.3ml/kg
What cells make up normal plueral fluid?
- mesothelial cells
- Monocytes/macrophages
- Lymphocytes
- Neutrophils under 2%
1500-2500 cells/uL
Protein less than 2.5g/dL
What % of dogs have a dorsal thoracic lymph center?
25%
What are the only parts of the body that are NOT drained by the thoracic duct?
- Right thoracic limb
- Right shoulder
- Cervical regions
Drained by the right lymphatic duct
What is the cisterna chyli and where is it located?
- Bipartite, dilated, retroperitoneal lymph channel, ventral to L1-L4 along cranial abdominal aorta
- Most cmmonly sits ventral to L3, caudal to coeliac and cranial mesenteric arteries
What is the major difference in the thoracic duct anatomy in dogs and cats?
- Dogs - travel on RIGHT side through caudal thorax, dorsolateral to aorta.
- Cats: On the LEFT!
Where does the thoracic duct drain into?
Left external jugular vein or jugulosubclavian vein
(Significant anatomical variation - some branches may terminate in azygous)
What embryonic structure forms the thymus?
At what age does it stop growing and starts to involute?
From the 3rd pharyngeal pouch.
4-5 months
What is the normal functional residual capacity (volume of air remaining in lung at end of expiration)
45ml/kg IMPORTANT
What fluid dynamics favor pleural fluid production and absorption?
What is the law that describes this called?
- Increased hydrostatic pressure of systemic and pulmonary capillaries compared to pleural fluid favors pleural fluid production
- Increased osmotic pressure of systemic and pulmonary vascular beds are greater than pleural fluid, favoring absorption
Tends to enter pleural space from parietal pleura and be absorbed by visceral pleura
Starling’s law
What are the functions of the thymus?
Cell mediated immunity
- maturation and selection of T-cells
- Termination of defective or autoreactive thymocytes
Endocrine
- Secretes a whole bunch of hormones for T-cells and enhancement of immune function
How do you classify pleural transudate, modified transudate and exudate?
Transudate: Protein <2.5, <1500 NCC
Modified: 2.5-5, NCC 1500-<7000
Exudate >3, NCC >7000
What can cause a pure pleural transudate?
- Hypoproteinaemia
- Increased hydrostatic pressure as with CHF (NT-proBNP significantly higher in cats with effusion from heart disease)
*any transudate can become a modified with chronicity
What are differentials for a serosanguinous (modified transudate) effusion?
- Lung lobe torsion
- D-hernia with liver entrapment
- Pericardial effusion
- Right sided heart failure
- Neoplasia (diffuse mesothelioma or carcinomatosis)
- Idiopathic pleuritis
What are differentials for a sanguinous (PCV similar to peripheral blood) effusion?
- Trauma
- Coagulopathy
- Acute lung lobe torsion
- Iatrogenic
- Tumours (chemodectoma, right atrial HSA)
