Pleural Diseases

Question 1

Are most pleural effusions symptomatic?

Answer 1

Nope, slow developing ones tend to be asymptomatic (unless they are tension or large)

Question 2

What is the embryonic origin of the lung?

Answer 2

mesothelial

Question 3

“Layers of collagen and elastin covered by a single layer of mesothelium.”

this describes what?

Answer 3

the parietal and visceral pleura

Question 4

Which layer of the pleura plays the main role in producing pleural fluid?

Answer 4

the parietal pleura

Question 5

Where do the pleura receive blood from?

Answer 5

Systemic circulation

Question 6

Where in the pleural layers is microvascular fluid filtration pressure lower? why?

Answer 6

microvascular fluid filtration pressure is lower in the visceral pleura because the bronchial circulation, which supplies the visceral pleura, drains into low pressure pulmonary veins.

Question 7

Which is thicker: the visceral or parietal pleura?

Answer 7

visceral

Question 8

Which layer of the pleura has lymphatic stomata? what does this imply?

Answer 8

only the parietal pleura contains lymphatic stomata between mesothelial cells that communicate directly with the lymphatics and provide a drainage system for pleural fluid.

Question 9

When is pleural symphysis done? why?

Answer 9

in individuals who develop spontaneous pneumothorax, to prevent their formation

Question 10

What is the pulmonary interstitium? how is it related to the alveolar-capillary interface and the pleural space?

Answer 10

The pulmonary interstitium, which is bordered by the visceral pleura, is a physiologically distinct compartment from the pleural space and contains the alveolar-capillary interface.

Question 11

What role does pleural fluid serve in health?

Answer 11

mechanical coupling of the lung, chest wall, and diaphragm

Question 12

Which hydrostatic pressure gradient drives the filtration of blood to make pleural fluid?

Answer 12

systemic capillaries to the microvascular interstitium of the parietal pleura form fluids. Microvascular filtrate is then “pulled” through the mesothelial lining of the parietal pleura into the pleural space by a small pressure gradient (approximately -10 cmH2O) between the parietal pleura interstitium and the subatmospheric pressure of the pleural space.

Question 13

What creates the negative pressure of the pleural space?

Answer 13

This negative pressure results from a combination of pleural surface pressure (a balance between the opposite recoil pressures of the lung and chest wall) and pleural liquid pressure (which is generated largely by the strong pumping action of the parietal lymphatics).

Question 14

Congestive heart failure would be expected to affect what part of the Starlings forces, leading to pleural effusion?

Answer 14

increase microvascular hydrostatic pressure

Question 15

Nephrotic syndrome would be expected to affect which aspect of the starlings forces, leading to pleural effusion?

Answer 15

decreased microvascular oncotic pressure

Question 16

Malignancy could be expected to affect which aspect of the starlings forces that lead to pleural effusion?

Answer 16

obstruct lymphatic drainage (i.e. obliterating pressure gradients by blocking flow)

Question 17

What effect would a trapped lung have on the starlings forces that lead to pleural effusion?

Answer 17

decreased pleural space pressure would decrease pressure gradients for drainage

Question 18

What effect does parapneumonic effusion have on starlings forces, leading to pleural effusion?

Answer 18

increased permeability of capillaries or pleural lining

Question 19

Does the Lights criteria identifies a pleural effusion as an exudate or a transudates?

Answer 19

exudates

Question 20

What is the pleural fluid total protein/serum total protein cut off for classification of an exudate?

Answer 20

> 0.5

Question 21

what is the lactate dehydrogenase cut off for the classification of an exudate?

Answer 21

> 0,6

Question 22

What is the cut off for pleural fluid LDH v. serum LDH to classify an effusion as an exudate?

Answer 22

Pleural fluid LDH > 2/3 of the upper normal value of serum LDH

Question 23

Why do the Lights criteria focus on the protein concentration of pleural fluid?

Answer 23

concentration of protein in the pleural fluid is a rough estimate of the leakiness of the pleural membrane to protein

Question 24

What does LDH tell us about the pleural effusion that is important?

Answer 24

The pleural fluid LDH correlates with the amount of inflammation in or near the pleura.

Question 25

Under what conditions do exudative effusions occur?

Answer 25

increases in pleural fluid protein and LDH (i.e. exudative effusions) occur when the pleural membrane is leaky or inflamed

Question 26

Under what conditions do transudative effusions occur?

Answer 26

low pleural fluid protein and LDH (i.e. transudative effusions) occur when alterations of the Starling hydrostatic forces cause increased fluid formation across a normal membrane

Question 27

What is a clinical scenario in which the Light’s criteria could give a false positive result for exudate?

Answer 27

patients with known heart failure who have been treated with diuretics, which increases the protein content of the effusion creating a “false positive” exudate. The best of these criteria is a pleural fluid cholesterol value of > 45 mg/dl defines an exudate.

Question 28

What do we look at to determine if the Lights criteria has given a false positive for exudate?

Answer 28

pleural fluid cholesterol value of > 45 mg/dl defines an exudate

Question 29

1. Congestive heart failure
2. Liver Cirrhosis
3. Nephrotic syndrome
4. Atelectasis
5. Hypothyroidism
6. Pulmonary embolus
7. Peritoneal Dialysis

Are these transudative effusions or exudative?

Answer 29

transudative

Question 30

Congestive heart failure: transudative or exudative?

Answer 30

transudative

Question 31

liver cirrhosis: transudative or exudative?

Answer 31

transudative

Question 32

nephrotic syndrome: transudative or exudative?

Answer 32

transudative

Question 33

atelectasis: transudative or exudative?

Answer 33

transudative

Question 34

hypothyroidism: transudative or exudative?

Answer 34

transudative

Question 35

pulmonary embolus: transudative or exudative?

Answer 35

transudative

Question 36

peritoneal dialysis: transudative or exudative?

Answer 36

transudative

Question 37

1. Neoplasm
2. Infections in the pleural space
3. Infections abutting the pleural space
4. Pulmonary embolus
5. Collagen vascular disease
6. Drug induced pleural disease
7. Gastrointestinal disease (esophageal perforation, pancreatitis)
8. Post-pericardotomy or post-myocardial infarction syndrome
9. Uremia
10. Asbestos exposure
11. Meig’s Syndrome (ovarian tumor + ascites + pleural effusion)
12. Yellow nail Syndrome (pleural effusions + lymphedema + yellow nails)
13. Iatrogenic injury
14. Hemothorax
15. Chylothorax

Transudative or exudative?

Answer 37

Exudative

Question 38

What are possible symptoms of a large pleural effusion?

Answer 38

nonproductive cough and chest discomfort

Question 39

What does pleuritic chest pain indicate when evaluating a pleural effusion?

Answer 39

inflammation of parietal pleura as only the parietal pleura is innervated

Question 40

What is the test of choice for confirming a pleural effusion?

Answer 40

bedside ultrasound

Question 41

When do pleural effusions require drainage?

Answer 41

large and symptomatic or infection

Question 42

Is the pH of pleural fluid typically higher or lower than the serum?

Answer 42

usually higher due to bicarb transport

Question 43

What do low pH pleural effusions indicate?

Answer 43

Low pH pleural effusions are seen most commonly in infected parapneumonic effusions (pleural effusions adjacent to a pneumonia)

can also occur in patients with malignancies with extensive pleural involvement, and esophageal perforation

Question 44

When is a pH of less than 7.2 an indication for chest tube drainage?

Answer 44

In the setting of pneumonia accompanied by an exudative effusion (parapneumonic effusion), a pH of less than 7.2 is generally considered an indication for chest tube drainage.

Question 45

When are low glucose pleural effusions seen?

Answer 45

Low glucose effusions are seen with infection, malignancy with extensive pleural involvement, and rheumatoid arthritis

Question 46

What is the number of thoracenteses that hae good sensitivity for detecting malignancies?

Answer 46

2

Question 47

A pleural effusion with a predominance of polymorphonuclear cells indicates what etiology?

Answer 47

infection

Question 48

a pleural effusion with a predominance of lymphocytes indicates what etiology?

Answer 48

a predominance of lymphocytes can be seen with malignancy and tuberculous or fungal effusions

Question 49

What does a hemothorax usually indicate?

Answer 49

trauma

Question 50

What is the hematocrit or RBC count that defines a hemothorax?

Answer 50

> 50% compared to peripheral blood

Question 51

What is empyema?

Answer 51

pleural effusion with purulence

Question 52

What is required for the diagnosis of empyema?

Answer 52

chest tube or surgical drainage

Question 53

Are elevated adenosine deaminase levels in pleural effusions specific or sensitive for tuberculous effusions?

Answer 53

specific but not senstivie

Question 54

At what point does air stop flowing from the lungs to the pleural space during a pneumothorax?

Answer 54

When the lung is punctured, air continues to flow into the pleural space until the inspiratory pleural pressure approaches atmospheric pressure and flow ceases.

Question 55

Define a tension pneumothorax. At what point does it compromise right heart filling?

Answer 55

ball valve type holes in the lung which limit expiratory flow out of the pleural space, leading to very high positive pleural pressures.

When pressures equal right atrial pressure, filling is impaired

Question 56

Among what population of patients are tension pneumothoraces common?

Answer 56

mechanically ventilated patients

Question 57

Are pleural effusions or pneumothoraces symptomatic?

Answer 57

pneumothorax

Question 58

What are the three types of pneumothorax that require chest tube drainage?

Answer 58

1. large
2. increasing in size
3. develop during mechanical ventilation

Question 59

1. Name the 3 Light’s Criteria (meeting any one of the following means you have an exudative effusion)

Answer 59

a. Pleural fluid total protein/serum total protein >0.5
b. Pleural fluid lactate dehydrogenase (LDH)/serum LDH > 0.6
c. Pleural fluid LDH > 2/3 of the upper normal value of serum LDH

Question 60

Name the 2 most common causes of a transudative pleural effusion

Answer 60

a. Congestive heart failure (by far the most common)

b. Cirrhosis

Question 61

How can a pneumothorax lead to cardiac arrest?

Answer 61

If a hole in the lung functions as a ball valve limiting expiratory flow out of the pleural space, very high positive pleural pressures can develop. When these pressures exceed right atrial pressure, venous return (and subsequently cardiac output) falls leading to cardiac arrest. This life-threatening condition is called a tension pneumothorax and requires immediate drainage of the pleural space.