Pleural Space

Question 1

What is the pleural space and what is it filled with?

Answer 1

It is a very thin space between parietal and visceral pleura (0.8mm in diameter) and it is filled with a small amount of fluid (capillary film for lubrication).

Question 2

What does the pleura contain?

Answer 2

Fluid, blood vessels and lymphatics

Question 3

Is the pleural space seen radiographically?

Answer 3

Not normally. Seen if the pleural space is filled with fluid, cellular, or fibrinous material (pleural effusion). Seen if pleural space is filled with gas (pneumothorax), thickened pleura or deposition of calcium, infiltration of lung tissue underlying the visceral pleura.

Question 4

Causes for pleural effusion

Answer 4

1. Increased systemic venous pressure and lymphatics (R or L HF)
2. Low colloidal osmotic pressure
3. Increased capillary permeability due to neoplasia, infection, or trauma
4. Diaphragmatic hernia with incarceration of the liver

Question 5

What do you need to do to definitively differentiate what kind of pleural effusion is present?

Answer 5

Thoracocentesis

Question 6

Free Pleural Effusion

Answer 6

Moves freely across mediastinal separation, gravity dependent.

Question 7

Trapped pleural effusion

Answer 7

Atypical distribution of the pleural fluid, but still moves with gravity.

Question 8

Encapsulated pleural effusion - give 2 examples

Answer 8

Loculated fluid by fibrinous deposits or adhesions and unable to be moved by gravity (pyothorax, chronic pleuritis)

Question 9

Radiographic signs of pleural effusion - Lateral View

Answer 9

1. Interlobar fissures
2. If enough fluid - Silhouette sign with Heart and/or Diaphragm (films look underexposed)
3. “leafing” of the lung lobes - (retraction of lung lobes)

Question 10

Radiographic signs of pleural effusion - DV/VD view

Answer 10

1. Retraction of lung lobes form body wall
2. Rounding of costophrenic angle (especially DV)
3. Widening of mediastinum b/c of communication
4. +/- silhouette sign with heart/diaphragm

Question 11

When radiographing pleural effusion, small amounts of fluid are best seen when?

Answer 11

On expiration and on erect horizontal beam views; and DV might be more helpful to see pleural fissuures

Question 12

What is the costophrenic angle?

Answer 12

Where lungs should meet the diaphragm

Question 13

Causes of hydrothorax

Answer 13

1. Heart Failure
2. Hypoproteinemia
3. Diaphragmatic hernia

Question 14

Causes of hemothorax

Answer 14

1. Trauma (blood clots)
2. Coagulopathy (blood often does not clot)
3. Neoplasia (blood does not clot - ex hemangiosarcoma)

Question 15

Chylothorax presents with pathological signs of:

Answer 15

Often fibrosis and permanent rounding of lung lobes when chronic

Question 16

Lung lobe torsion can cause a transudate pleural effusion. What lobes are most commonly affected:

Answer 16

Right middle and left cranial lung lobes

Question 17

Lobe lobe torsion occurs most commonly in what kind of dogs?

Answer 17

Large breeds, deep chested dogs

Question 18

Lung lobe torsion presents as:

Answer 18

Non-inflated lung lobe, +/- air bronchogram, pleural effusion but cannot determine all the lung lobes

Question 19

Hydrothorax, hemothorax, chylothorax, neoplasia, and lung lobe torsion are all examples of what kind of pleural effusion?

Answer 19

transudate

Question 20

Causes of pyothorax

Answer 20

1. Systemic
2. Penetrating wounds
3. Foreign body

Question 21

Pyothorax in the cat often involves the ______ and can be _____.

Answer 21

Hemithorax, restrictive

Question 22

Pleuritis - radiographic appearance

Answer 22

Similar findings as hydrothorax with added feature of a white line around the lung due to thickened pleura. The parietal pleural thickening is best seen on the VD view between the ribs. The pleural thickening may restrict expansion of lung with resulting ‘clover-leaf.’

Question 23

Pyothorax and pleuritis are examples of what kind of pleural effusion?

Answer 23

exudate

Question 24

While a pneumothorax can cause a heart to appear elevated off the sternum on radiographs, what else can cause this impression?

Answer 24

When an animal is in shock - so much so that it is enough to have a small cardiac silhouette (cardiovascular shock)

Question 25

Pneumothorax - radiographic findings on a lateral view

Answer 25

1. Heart appears elevated off sternum
2. Retraction of lobar borders
3. Increased opacity of LUNG field
4. Lack of vascular markings in the periphery of the lung field
5. Flattened diaphragm
6. +/- Atelectasis and pulmonary contusions (depends on how much trauma involved)

Question 26

Why does the heart appear elevated off the sternum in a pneumothorax?

Answer 26

It is not being kept in normal position as it would by inflated lung lobes. Therefore it “falls” away from the sternum, instead of being elevated.