Lecture 17: Respiratory 2 Flashcards
Define atelectasis
It is the incomplete expansion of alveoli that can affect the whole lung or just part of it
What is the gross appearance of atelectasis
dark and sunken
What are the types of atelectasis
congential
acquired
- compressive
- obstructive
What does congenital atelectasis indicate
It indicated the the neonatal lungs are not inflating
May be obstructed with meconium or amniotic fluid in the bronchi or bronchioles
If it is focal it can resolve over time
If it is diffuse it can indicate underlying problems
- acidosis/distress causing aspiration of fluid
- surfactant problems resulting in alveoli that can’t stay open (higher risk if premature
What might cause compressive atelectasis
external compression from something outside the lung in the thorax
- space occupying mass like a tumor/abccess/neoplasia
- bloat
- pyothorax
What might cause obstructive atelectasis
Blockage of airway from inside the lung
- mucus
- exudate
- aspiration
Narrowing lumen
- edema
- inflammation
Define emphysema
It is the distension and rupture of alveoli
How does emphysema present grossly
It is ‘bubbly’ and has crepitus
Due to air bubble/bullae formation in the parenchyma or connective tissue
What are the 2 types of emphysema and which occurs in animals
primary - not in animals (due to inhalation of smoke)
secondary - found in animals (secondary to disease)
What are 2 mechanisms that result in secondary emphysema
- obstruction to outflow
- bronchopneumonia because the exudate acts as a 1 way valve which allows air to enter but prevent its escape - agonal change
- normal at slaughter
- excess airway constriction from gasping against a closed airway
- more common at the edges of the lung
Define pulmonary congestion
Passive accumulation of blood in the lungs
not the same as hyperemia
What might cause pulmonary congestion
heart failure
- stagnation of blood in pulmonary vessels can result in leakage
- intra alveolar hemorrhage
gradual causes
- DIC
- vasculitis
- septicemia
- coagulopathy
sudden = erosion of the pulmonary artery = sudden hemoptysis and death
It can also be an artifact of death via jugular cutting or blunt force trauma
What is the gross features of pulmonary congestion
heavy, edematous lungs with hemorrhagic/serosanguinous fluid that oozes when cut
Define pulmonary edema
It is the accumulation of fluid in the pulmonary interstitium and alveoli
The fluid accumulation overwhelms the macrophage’s ability to resorb
- the macrophages become less effective when they are floating
fluid leak > fluid resorb (or lymph drainage)
What are 2 categories of pulmonary edema
cardiogenic/hydrostatic
permeability/inflammatory
List 4 causes of cardiogenic or hydrostatic pulmonary edema
congestive heart failure
iatrogenic fluid overload
hypoproteinemia
reduced lymph drainage or a lymph blockage
List 4 causes of permeability or inflammatory pulmonary edema
general inflammation resulting in leaky vessels
viral or toxic lung disease
acute respiratory distress syndrome (ARDS)
shock
Are necropsy findings diagnostic for ARDS? If so what findings indicate this disease?
No cant diagnose from a necropsy alone
What are the gross features of pulmonary edema
lots of froth in the trachea (only a little froth is an agonal change at death)
failure of lung to collapse
- can see the intralobular septa and rib impressions
heavy/dark/wet
- ooze serosanguinous fluid
What is the histologic features of pulmonary edema
pink fluid in the alveoli
List 4 types of pulmonary embolisms and what are their features?
Thromboemboli (insignificant - fibrinolysis will degrade)
septic or bacterial emboli (from vegetative valvular endocarditis resulting in embolic pneumonia and abcess/hemorrhage)
fat emboli from bone fractures
tumor emboli (common)