Ch.6 - Recognizing a Pleural Effusion

Question 1

Approx. …L of fluid will cause opacification of the entire hemithorax in an adult.

Answer 1

2L.

Question 2

Subpulmonic effusions:

Answer 2

Most pleural effusions begin life collecting in the pleural space between the hemidiaphragm and the base of the lung –> These are called subpulmonic effusions.

Question 3

As the amount of fluid increases, it forms a … shape on the upright frontal chest radiograph due to the natural elastic recoil properties of the lung.

Answer 3

Meniscus.

Question 4

Loculated effusions:

Answer 4

With pleural adhesions (usually from old infection or hemothorax) the fluid may assume unusual appearances or occur in atypical locations. Such effusions are said to be loculated.

Question 5

Pseudotumor:

Answer 5

It is a type of effusion that occurs in the fissures of the lung (mostly the MINOR fissure) and is most frequently 2o to CHF.
It clears when the underlying failure is treated.

Question 6

Laminar effusions:

Answer 6

Are best recognized at the lung base just above the costophrenic angles on the frontal projection and most often occur as a result of either CHF or lymphangitic spread of malignancy.

Question 7

A hydropneumothorax:

Answer 7

Consists of both air and increased fluid in the pleural space and is recognizable on an upright view of the chest by a straight, air-fluid interface rather than the typical meniscus shape of pleural fluid alone.

Question 8

Pleural fluid is produced primarily at the … pleura?

Answer 8

PARIETAL

Question 9

Pleural fluid is resorbed at the … pleura + by LYMPHATIC drainage through the … pleura.

Answer 9

visceral, parietal.

Question 10

How can atelectasis cause a pleural effusion?

Answer 10

Via decreased pressure in the pleural space.

Question 11

MCC of an EXUDATE pleural effusion is?

Answer 11

Malignancy

Question 12

Hemothorax?

Answer 12

Has a fluid Ht >50% of blood Ht.

Question 13

SLE pleural effusions - Which side?

Answer 13

Usually BILATERAL, but when UNILATERAL, the effusions are usually LEFT-SIDED.

Question 14

3 conditions that can produce effusions on EITHER side, but are usually UNILATERAL?

Answer 14

1. TB, and other infectious agents, including viruses.
2. Pulmonary thromboembolic disease.
3. Trauma.

Question 15

Diseases that usually produce LEFT-SIDED effusions?

Answer 15

1. Pancreatitis.
2. Distal thoracic duct obstruction.
3. Dressler.

Question 16

Diseases that usually produce RIGHT-SIDED effusions?

Answer 16

1. Abdominal disease related to the liver or ovaries (Meigs syndrome).
2. RA - Effusion unchanged for years.
3. Proximal thoracic duct obstruction.

Question 17

Dressler syndrome presentation?

Answer 17

Typically occurs 2-3 weeks after a transmural MI producing:

1. Left pleural effusion.
2. Pericardial effusion.
3. Patchy airspace disease at the left lung base.

Question 18

How much pleural fluid is needed for the POSTERIOR costophrenic SULCUS to be blunted?

Answer 18

75mL.

Question 19

When the effusion reaches about … mL in size, its blunts the lateral costophrenic angle, visible on the frontal CXR.

Answer 19

300mL.

Question 20

Pitfall about blunting of the costophrenic angles?

Answer 20

Pleural THICKENING caused by FIBROSIS can also produce blunting of the costophrenic angle.

Question 21

Solution for the pitfall about blunting of the costophrenic angle due to pleural thickening?

Answer 21

1. Scarring sometimes produces a characteristic SKI-SLOPE appearance of blunting, UNLIKE the meniscoid appearance of a pleural effusion.
2. Pleural thickening will NOT change in location with a change in patient position, as most effusions will.

Question 22

Right-sided subpulmonic effusion - FRONTAL view:

Answer 22

1. Highest point of the APPARENT* hemidiaphragm is displaced more LATERALLY than the highest point of a normal hemidiaphragm would be.
2. More difficult to recognize due to liver.

Question 23

Right-sided subpulmonic effusions - Lateral view?

Answer 23

Posteriorly, the APPARENT* hemidiaphragm has a curved arc, but as it meets the junction with the major fissure –> Assumes a flat edge that drops sharply to the anterior chest wall.

Question 24

Left-sided pleural effusions - Frontal view?

Answer 24

1. Distance between the stomach bubble and the apparent LEFT hemidiaphragm is increased (normally only about 1cm from top of stomach bubble to bottom of aerated left lower lobe).
2. Highest point of the apparent hemidiaphragm is displaced more LATERALLY than the highest point of a NORMAL hemidiaphragm would be.

Question 25

Left-sided effusions - Lateral view?

Answer 25

Posteriorly, the apparent hemidiaphragm has a curved arc, BUT as it meets the junction with the major fissure --> assumes a FLAT EDGE that drops sharply to the ANTERIOR chest wall.

Question 26

3 purposes of LATERAL decubitus views?

Answer 26

1. Confirm the presence of a pleural effusion. 2. Determine whether a pleural effusion flows freely in the pleural space or not --> IMPORTANT BEFORE ATTEMPTING TO DRAIN PLEURAL FLUID. 3. "Uncover" a portion of the underlying lung hidden by the effusion.

Question 27

Pleural fluid may NOT flow freely if?

Answer 27

ADHESIONS ARE PRESENT, that might impede the free flow of the fluid (loculated effusions).

Question 28

Decubitus vies of the chest can demonstrate effusions as small as ...-... mL.

Answer 28

15-20mL (CT have largely replace them).

Question 29

Don't order a decubitus when?

Answer 29

If the ENTIRE hemithorax is opacified --> No change in the position of the fluid.

Question 30

When the hemithorax of an adult contains about ...L of fluid, the entire hemithorax will be opacified.

Answer 30

2L.

Question 31

When we have a large effusion, what should we order in order to visualize the underlying lung?

Answer 31

CT.

Question 32

Loculated effusions can be suspected when?

Answer 32

An effusion has an unusual shape or location in the thorax.

Question 33

Is loculation of the fluid therapeutically important?

Answer 33

YES - Indicates multiple adhesions that make it difficult to drain the non communicating pockets of fluid with a single pleural drainage tube in the same way free flowing effusions can be drained.

Question 34

Pseudotumors in CXR are what?

Answer 34

Sharply marginated collection of pleural fluid contained BETWEEN the layers of an INTERLOBAR PULM. FISSURE or in a subpleural location just beneath the fissure. TRANSUDATES that almost always occur in patients with CHF.

Question 35

Imaging findings of a pseudotumor:

Answer 35

1. Lenticular in shape, most often occur in the MINOR fissure (75%). 2. Pointed ends on each side where they insinuate into the fissure, much like the shape of a lemon. 3. They do NOT tend to flow freely with a change in patient positioning.

Question 36

Recurrences of pseudotumors?

Answer 36

They disappear when the underlying condition (usually CHF) is TREATED, but they tend to recur in the same location each time the patient's failure recurs.

Question 37

What is a LAMINAR pleural effusion?

Answer 37

A form of pleural effusion in which the fluid assumes a THIN, BANDLIKE density along the LATERAL chest wall, especially near the costophrenic angle. --> Unlike the usual pleural effusion, the lateral costophrenic angle tends to maintain its acute angle with a laminar effusion.

Question 38

Laminar effusions are almost always the result of?

Answer 38

Elevated LA pressure, as in CHF or 2o to lymphangitic spread of malignancy. Usually NOT free-flowing.

Question 39

Hydropneumothorax?

Answer 39

Presence of BOTH air + abnormal amounts of fluid in the pleural space.

Question 40

Some of the common causes of hydropneumothorax:

Answer 40

1. Trauma. 2. Surgery. 3. Recent tap to remove pleural fluid in which air enters the pleural space.

Question 41

What is a bronchopleural fistula?

Answer 41

An abnormal and relatively UNCOMMON connection between the bronchial tree and the pleural space.

Question 42

Causes of bronchopleural fistula?

Answer 42

1. Tumor. 2. Surgery. 3. Infection.

Question 43

Imaging features of hydropneumothorax?

Answer 43

A hydropneumothorax produces an air-fluid level in the hemithorax marked by a STRAIGHT edge + a SHARP, air-over-fluid interface when the exposure is made with a horizontal x-ray beam.

Question 44

Why is CT frequently necessary to distinguish between some presentations of hydropneumothorax?

Answer 44

Because also a lung abscess may have a similar appearance on conventional chest radiographs.

Question 45

About ...mL are required to blunt the posterior costophrenic sulcus (seen on the lateral view) and about ...-...mL to blunt the lateral costophrenic sulcus (seen on frontal view).

Answer 45

75mL. | 200-300mL.