Chapter 105 Thoracic Cavity Flashcards
Describe the lymph supply in the lungs
Pulmonary lymph nodes (not present in all dogs) receive lymph from the lungs and drain into the tracheobronchial nodes
Tracheobronchial nodes empty into mediastinal or other tracheobronchial nodes
Where does the thoracic duct travel in dogs vs cats
Thoracic duct starts in the sublumbar region as a cranial continuation of the cisterna chyli.
In the caudal thorax, the thoracic duct travels dorsolateral to the aorta on the right in dogs*
In the left in cats
What is the function of the thoracic duct and what does it drain
Primary channel for return of lymph in most of the body except—Right thoracic limb, shoulder, and cervical region which is drained by right lymphatic duct
What is the functional residual capacity of the lungs and how to estimate
Volume of air remaining in the lung at the end of normal exhalation = ~45 ml/kg
Represents the point at which all forces, collapse of lungs and expansion of chest cavity, are in passive equilibrium
Calculate tidal volume in dogs
10-20 ml/kg
Fluids tend to enter the _____ space from the _______ pleura and be absorbed by the _____ pleural and _____ pleural lymphatics
Fluids tend to enter the pleural space from the parietal pleura and be absorbed by the visceral pleural and parietal pleural lymphatics
Pleural effusion effect on tidal volume
When pleural space is enlarged by fluid, air, or a mass, tidal volume is decreased and an increase in respiratory frequency will be the response to maintain minute ventilation
Starling law
Effects of differences in hydrostatic and osmotic pressure on net filtration
Are the systemic and pulmonary capillary hydrostatic pressures greater than/or less than those of the pleural space
Greater than - pleural fluid production is favored
Osmotic pressure of systemic and pulmonary capillaries compared to intrapleural fluid
Osmotic (same as oncotic) pressure (Pulls) of the systemic and pulmonary vascular beds are also greater than those of the intrapleural fluid, favoring absorption of fluid across the parietal and visceral pleura.
Protein, cell count, and Specific gravity of chylous effusion
Usually modified transudate - Protein 2.5-4
Cell count < 7000
SPG <1.032
Diagnostic tests for chyle
Compare serum triglyceride and cholesterol to effusion
If chyle, triglyceride in effusion will be greater than in serum
If chyle, cholesterol in effusion will be less than in serum
Other tests – check for chylomicrons, stain with Sudan black, or positive ether clearance test
Effects of pleural effusion dogs
Change central and peripheral BP
Right atrial collapse
Signs of cardiac tamponade
In cats with normal pericardial and cardiac function 20 ml/kg of pleural fluid caused ____
increased CVP and removal caused decrease in CVP
Cell count, protein count, and specific gravity of a transudate
Cells < 1500
Protein < 2.5
SPG <1.015
