SM 172 Pleural Diseases Flashcards

1
Q

Describe the pleural place normally?

A

Normally, the pleural space is a thin layer of cells that is often described as a potential space

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2
Q

What lines the chest wall?

A

Parietal pleura

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3
Q

What lines the lungs?

A

Visceral pleura

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4
Q

If one pleural space is compromised, what happens to the other?

A

No effect on the other; there are two distinct pleural spaces on either side of the body that do not connect

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5
Q

What is the main function of the pleura?

A

Lubricate the organs and act as a reservoir for excess lung fluid, delaying the formation of pulmonary edema

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6
Q

Which pleural lining receives blood flow from the systemic circulation?

A

Both the parietal and visceral pleura receive blood flow from the systemic circulation

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7
Q

Which pleural layer is under higher pressure?

A

The parietal layer is under higher pressure because the visceral pleura drains into the lower pressure pulmonary veins, and is thicker, diminishing the pressure difference

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8
Q

What differentiates the Parietal and Visceral pleura?

A

Parietal is higher pressure, has lymphatic stoma, and is thinner; Visceral is low pressure, lacks lymphatic drainage, and is thicker

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9
Q

What sets the balance of fluid flow in the interstitial space?

A

The Frank-Starling equation: Q = K*((Pv - Pi)-u(Oi-Op)); Q always refers to flow out of the vessels

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10
Q

What happens in the pleural space at rest, with respect to filtration and drainage?

A

Normally, Q is slightly positive leading to fluid influx into the pleural space, which is drained by the lymphatic stoma

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11
Q

What do the parietal lymphatic stoma do?

A

They generate a strong rhythmic pumping action that creates a negative pressure which sucks fluid out of the interstitial space

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12
Q

What does the development of a pleural effusion suggest?

A

Pleural effusions develop when there is an imbalance between filtration and drainage in the pleural space

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13
Q

What is the radiographic correlate of a Pleural Effusion?

A

On CXR, a meniscus sign is seen during a Pleural Effusion

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14
Q

What is a Meniscus sign?

A

A fuzzy curved line that appears in a lung during a Pleural Effusion

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15
Q

How does congestive heart failure precipitate pleural effusion?

A

CHF increases microvascular hydrostatic pressure leading to pleural effusion

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16
Q

How does low albumin and nephrotic syndrome precipitate pleural effusion?

A

Decreased vascular oncotic pressure favors filtration and leads to pleural effusion

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17
Q

How does malignancy cause pleural effusion?

A

Malignancy can obstruct lymphatic drainage leading to pleural effusion

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18
Q

How does trapped lung lead to pleural effusion?

A

An abnormally thickened visceral pleura decreases pleural space pressure and favors filtration leading to pleural effusion

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19
Q

How does increased permeability of capillaries or pleural lining lead to pleural effusion?

A

Damage to the capillaries via ARDS leads to the filtration coefficient dropping to 0, therefore cancelling the effects of the oncotic pressure gradient and allowing the hydrostatic pressure gradient to drive filtration out of the capillaries and cause pleural effusion

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20
Q

How does pleural effusion present?

A

Pleural effusion is often asymptomatic, but may have nonspecific symptoms like cough and edema

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21
Q

Why is pleural effusion often asymptomatic?

A

Due to hypoxic vasoconstriction

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22
Q

How does pleural effusion show up on physical exam?

A

Dull to percussion and decreased breath sounds

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23
Q

What is a tension pleural effusion?

A

Occurs when an entire lung is compressed by a pleural effusion and pressure builds up on one side, displacing the heart and other mediastinal structures as well as impairing venous return to the heart and dropping CO

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24
Q

Is CXR able to diagnose a pleural effusion?

A

Sometimes; but it’s possible to miss it

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25
Q

What does a pleural effusion look like on Ultrasound?

A

Black fluid above the lung

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26
Q

What is the benefit of an Ultrasound in pleural effusion treatment?

A

The ultrasound shows you a black space where you can stick a needle to drain the pleural effusion

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27
Q

What are the complicated effusions an Ultrasound can detect and why is this helpful?

A

Ultrasound can show loculated effusion (looks like lots of little cavities in the lung) as well as layering hemothorax, both of which require a large chest tube to drain the pleural effusion

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28
Q

What is the diagnostic test for a pleural effusion?

A

Thoracentesis, which obtains a sample of the pleural fluid

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29
Q

What are Light’s Criteria used for?

A

Classify a pleural effusion as exudative if any one of three conditions is met, or transudative if none of the three conditions are met

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30
Q

List the Light’s Criteria?

A

Pleural Total Protein/Total Serum Protein > 0.5
Pleural LDH/Serum LDH > 0.6
Pleural LDH > (2/3) of Upper Normal Serum LDH

31
Q

Are transudative effusions positive or negative on Light’s Criteria?

A

Transudative effusions are negative on all 3 of Light’s criteria

32
Q

What are common causes of transudative Pleural Effusion?

A

CHF, Cirrhosis, Nephrotic Syndrome

33
Q

What are common causes of Exudative pleural effusion?

A

Parapneumonic, malignancy, autoimmune disease, pulmonary embolism, pancreatitis

34
Q

What is the order of tests in classifying pleural effusion?

A

Ultrasound -> Thoracentesis -> If exudative, Cell Count/pH/Glucose/Cultures/Cytology

35
Q

After determining a pleural effusion is exudative, what is the point of a cell count?

A

High neutrophils = infection

High lymphocytes = malignancy, TB, autoimmune diseas

36
Q

What do high neutrophils in a pleural effusion tell you?

A

High neutrophils mean an infection is driving the pleural effusion

37
Q

What do high lymphocytes tell you in a pleural effusion?

A

High lymphocyte suggest a malignancy, TB, or autoimmune disease is driving the pleural effusion

38
Q

After determining a pleural effusion is exudative, what is the point of a pH?

A

pH < 7.2 (more acidic) indicates an active infection and requires directly inserting a large chest tube

39
Q

After determining a pleural effusion is exudative, what is the point of a Glucose measurement?

A

Low glucose = active infection

40
Q

After determining a pleural effusion is exudative, what is the point of growing cultures from the pleural effusion fluid?

A

If cultures are grown, common bacteria that cause community acquired bacteria can be detected

41
Q

After determining a pleural effusion is exudative, what is the point of cytology?

A

Search for malignant cells

42
Q

What is Empyema?

A

Empyema is pus in the pleural space, and indicates active infection with the need for drainage using a large chest tube immediately

43
Q

What is a Chylothorax?

A

Chylothorax is a triglyceride rich pleural effusion that occurs due to impaired lymphatic drainage, and can be cleared with a large chest tube

44
Q

How should a transdutative pleural effusion be treated?

A

Treat the cause of the pleural effusion, ie congestive heart failure, and the effusion will resolve on it’s own

45
Q

When is thoracentesis always indicated?

A

New, unilateral pleural effusion = thoracentesis

46
Q

What is Pneumothorax?

A

Air in the pleural space

47
Q

What are the 3 types of Pneumothorax?

A

Primary spontaneous, secondary spontaneous, and traumatic/iatrogenic

48
Q

What are the characteristics of a Primary Spontaneous Pneumothorax?

A

No underlying lung pathology, no inciting event, young thin patients, high recurrence rate

49
Q

What is a “lung line”?

A

In a pneumothorax, air flows into the pleural space and compresses the lung, creating an area on the periphery of the lung where lung markings are absent

50
Q

What are the characteristics of a Secondary Spontaneous Pneumothorax?

A

Spontaneous pneumothorax in the setting of underlying lung disease

51
Q

How does Cystic Fibrosis present on CXR?

A

Upper lobe predominant cysts and traction bronchiectasis

52
Q

What diseases can predispose secondary spontaneous pneumothorax?

A

Cystic Lung Diseases (CF), Infection (pneumonia), and Malignancy (cancer)

53
Q

How can cystic lung diseases predispose secondary spontaneous pneumothorax?

A

Cystic lung diseases create cysts in the lung that can pop and release air into the interpleural space

54
Q

How can infection predispose secondary spontaneous pneumothorax?

A

Infections can form cavitary lesions on the lung, such as S. Aureus, which can burst and release air into the interpleural space

55
Q

How can malignancy predispose secondary spontaneous pneumothorax?

A

Malignancy can erode the pleural lining and predispose pneumothorax

56
Q

How can trauma cause pneumothorax?

A

Trauma can puncture the parietal pleura and allow air to enter the pleural space, creating a pneumothorax

57
Q

What procedures can generate Iatrogenic pneumothorax and why?

A

IR Biopsies, Bronchoscopy, tracheal tube, central line placement; in these procedures, the pleural space may be punctured

58
Q

How might a tracheal tube form a pneumothorax?

A

If the tube is pushed too far into the lung, it can burst through the lung and pierce the parietal pleura, forming a pneumothorax

59
Q

How can a central line placement cause a pneumothorax?

A

The sharp tip of the line is normally inserted into the subclavian vein, but can break out of the vein and pierce the parietal pleura, resulting in a pneumothorax

60
Q

What is a trapped lung?

A

Inflamed visceral pleura that becomes scarred and permanently compresses the lung, allowing pleural effusions to form forever

61
Q

Can a trapped lung be treated with a chest tube?

A

No; even if the pleural effusion is drained, the lung is unable to expand and eventually the pleural effusion will reform

62
Q

What is the gold standard for diagnosis of a pneumothorax?

A

Chest CT, but ultrasound is being used more

63
Q

What is a lung point?

A

The lung point is where the intense line on ultrasound that represents both the visceral and parietal layers stops shimmering, as at this point gas is in between the two layers

64
Q

Which is worse, an open or closed pneumothorax?

A

Closed pneumothorax, because air cannot escape the chest cavity, resulting in worse hemodynamic effects

65
Q

Describe an open pneumothorax?

A

A hole in the parietal lining allows air to enter the pleural space and compress the lung, since the interpleural pressure becomes equal to atmospheric pressure; however, breathing can still occur because the interpleural pressure can be lowered and raised

66
Q

Why is expiration possible in an open pneumothorax but not a closed pneumothorax?

A

In an open pneumothorax, air can still escape through the hole in the parietal pleura, allowing expiration to occur

In a closed pneumothorax, the hole is a one way valve that only allows air in, but not out, blocking expiration

67
Q

Describe a closed pneumothorax?

A

A hole in the parietal pleura allows air in but not out of the pleural space, raising interpleural pressure greatly and shifting the mediastinal contents to restrict venous filling/cardiac output as well as inhibiting expiration

68
Q

How can a closed pneumothorax be seen on CXR?

A

The entire mediastinum is shifted in the opposite direction of the lobe with the pneumothorax

69
Q

What is a subcutaneous emphysema?

A

Air in the subcutaneous tissue that can be felt as popping, following a pneumothorax

70
Q

What is the emergency treatment for a pneumothorax?

A

Needle decompression

71
Q

How does needle decompression work?

A

In an emergency, it allows air to escape the pleural cavity, resulting in lowered interpleural pressure and increased venous return, raising cardiac output

72
Q

Is a pleural space required for life?

A

No

73
Q

What is a tension pneumothorax?

A

A pneumothorax that reaches high pressures which impair filling of the heart, causing circulatory collapse and require immediate drainage of the pleural space

74
Q

Why are ventilators a risk for tension pneumothorax?

A

Normal ventilation maintains a negative interpleural pressure; ventilated patients get Positive End Expiratory Pressure which raises PIP due to increased stretch of the lung, which can impair venous return to the heart