Pleural Space

Question 1

Pleural Anatomy

Answer 1

2 distinct sacs- left and right
Mediastinum is space between them
parietal and visceral pleura= contiguous- parietal lines thoracic cavity and visceral covers the lungs
Pleural space is between parietal and visceral pleura- this is a potential space
There is also pleural space between lung lobes
L and R pleural spaces communicate through microscopic fenestrations in mediastinal pleura- so its not a barrier to the spread of disease.

Question 2

Interlobar fissures

Answer 2

Division between lobes
Pleural fluid accumulates here= visible and is then called a fissure line
Pleural air does not accumulate in fissures
the fissures commonly seen are middle and cdcranial

Question 3

Radiographic anatomy

Answer 3

Normal pleura is not visible- it is thin and does not absorb enough xrays to be detected
the thin pleural lines can sometimes be seen and will have soft tissue opacity
the pleura may line up exactly with the beam and absorb enough xrays, pleura might be slightly thick, there will usually not be CS

Question 4

Pleural disease

Answer 4

Something in pleural space- pushing lung away from thoracic wall. very common
CS from space occupying nature of dz and secondary atelectasis. No signs to various degrees of dyspnea

Question 5

Pleural effusion

Answer 5

fluid in pleural space
produced by the pleura when irritated inflamed or infected
Always important- should be investigated

Question 6

Pneumothorax

Answer 6

gas in pleural space

enters from outside, mediastinum or lung

Question 7

Pleural mass

Answer 7

tumor-uncommon

diaphragmatic hernia

Question 8

Pleural effusion- causes

Answer 8

Heart failure-- common in cats
pyothorax
cancer- common
trauma
chylothorax
hypoproteinemia

Question 9

Pleural effusion-radiographic signs

Answer 9

Depend on volume of fluid, patient positioning (distribution of fluid affected), fluid type has no effect on appearance
Wide interlobar fissures- soft tissue opacity- in VD view
Lung retraction from thoracic wall- VD view
Scalloping of ventral lung margins-lateral
Silhouetting of heart- DV
Silhouetting of diaphragm- all views

Question 10

Interlobar fissures- Pleural effusion-

Answer 10

Thickness and number depend on amount of fluid present and position of patient
minimum of 100 mL of fluid needed for detection of wide fissures in ~40 lb dog- more of a long term thing
xray must strike the fissure tangentially

Question 11

pleural fluid

Answer 11

asymmetric fluid not common- pyothorax is a common cause
chronic fluid, especially exudate, causes pleural fibrosis- limits ability of lung to expand following fluid removal because it was irritated

Question 12

Pleural fluid fakeouts

Answer 12

Normal thin fissures
costal cartilages
chondrodystrophic morphology
scalloping due to fat in mediastinum

Question 13

Costal cartilage

Answer 13

Concave cranially
connects to rib
thicker

Question 14

Pneumothorax

Answer 14

Tear in lung involving visceral pleura- rupture of cavitary lung lesion. congenital or traumatic bulla
traumatic tear
Hole in thoracic wall from trauma or thoracocentesis
extension of pneumomediastinum
Usually bilateral
small without CS = no tx
persistent = needs intervention

Question 15

Pneumothorax- radiographic signs

Answer 15

Retraction of lung margin from thoracic wall- radiolucency between lungs and thoracic wall, lung markings do not extend to edge of thorax- lateral
Air around ventral heart margin- lateral
separation of heart from sternum- lateral

Question 16

Tension pneumothorax

Answer 16

Hole in lung or thoracic wall- functions as a one way valve
air enters pleural cavity on inspiration but cant escape on expiration
pleural pressure > atm pressure
cause marked atelectasis
emergency! 
Contralateral midline shift
flat diaphragm
cd displacement of diaphragm 
tenting of diaphragm

Question 17

Pneumothorax fakeouts

Answer 17

hypovolemia causing cardiac elevation
thoracic wall conformation causing cardiac elevation
skin fold creating peripheral radiolucency