Pleural Diseases

Question 1

Give conditions which can pleural effusions by the following mechanisms:

1. Increase in hydrostatic pressure
2. Decrease in oncotic pressure
3. Diaphragmatic defects -> is this considered transudate / exudate?

Answer 1

1. Congestive heart failure -
   #1 cause
2. Nephrotic syndrome (decreased serum proteins)
3. Liver disease, ascites
   -> transudate if simple liver disease
   -> exudate if associated with abdominal infection (i.e. SBP, pancreatitis)

Question 2

What processes can cause direct passage of fluid into the pleural cavity?

Answer 2

1. Rupture of thoracic duct
2. Rupture of esophagus
3. Iatrogenic from central catheter insertion

Question 3

How can malignancies and pneumonia cause pleural effusion?

Answer 3

Malignancy - capillary proliferation and impaired lymphatic drainage

Pneumonia - inflammatory process allows fluid to leak into pleural cavity

Question 4

What processes cause an exudate in the pleural effusions?

Answer 4

Pleural inflammation, infection, or malignancy -> high protein pulmonary edema (i.e. pneumonia, PE, malignancy)

Leaking from surrounding tissue -> mediastinum if esophagus ruptures, or chylothorax

Abdominal infections

Question 5

What are the symptoms of pleural effusion?

Answer 5

Symptoms - dyspnea (decreased gas exchange, possible lung collapse) and pleuritic chest pain (worse with inspiration)

Question 6

What are the clinical signs of pleural effusion?

Answer 6

Dullness to percussion, absence of fremitus, diminished / absent breath sounds, friction rub

Also signs & symptoms of underlying etiology of pleural effusion

Question 7

What is the most common way pleural effusion is diagnosed? What does this help differentiation it from?

Answer 7

Chest X-ray showing a layer of fluid in the pleura if the patient is in left lateral decubitus position

Atelectasis & consolidation will not move in the pleural cavity like this.

Note: Loculated (cystic) effusion will not be able to move like this

Question 8

What is the method of choice to locate pleural effusion in thoracentesis?

Answer 8

Chest ultrasound

Question 9

When is thoracentesis NOT done for draining pleural effusions? Why?

Answer 9

Whenever the clinically suspected reason is transudative: congestive heart failure, low protein, or cirrhosis of liver
-> resulting negative intrapleural pressure will cause more fluid to be pulled out of vessels

Question 10

When is thoracentesis generally indicated?

Answer 10

All exudative causes - want to prevent fibrotic adhesions in pleura

Also - in presence of CHF or cirrhosis if there is unexplained infection (evidence of inflammatory process)

Question 11

What are absolute contraindications for thoracentesis?

Answer 11

Lack of patient cooperation, severe coagulopathy, hemodynamic instability, local chest wall infection (can spread the infection inside)

Question 12

What are possible complications of thoracentesis?

Answer 12

Pneumothorax
Hemorrhage
Syncope
Infection
Puncture of spleen or liver
Re-expansion of pulmonary edema if >1L removed (negative intrapleural pressure)

Question 13

Where is thoracentesis typically done?

Answer 13

One interspace below the fluid level, above the rib, in midscapular line (use ultrasound for guidance).

Patient should be sitting up

Question 14

What tests is the pleural fluid typically sent for?

Answer 14

Cell count and differential

Chemistry: protein, glucose, pH, LDH

Culture: Gram stain and AFB stain with cultures

Cytology for malignant cells

Question 15

What additional tests should be ordered on the pleural fluid if there is clinical suspicion of the following causes:

1. Pancreatitis
2. Chylothorax
3. Cholethorax

Answer 15

Pancreatitis - amylase
Chylothorax - triglycerides:
>110 mg/dL is diagnostic (should appear milky white)
Cholethorax - bilirubin

Question 16

What are the criteria for calling an effusion an exudate: think protein and LDh

Answer 16

Any one of the following:

Pleural fluid protein is > 1/2 of serum protein

Pleural fluid LDH is >0.6 serum LDH

If no serum drawn: Pleural fluid is >2/3 upper limit of normal for serum LDH

Question 17

What are the criteria for cholesterol and protein absolutely to cause pleural effusion an exudate without serum to compare?

Answer 17

Pleural fluid cholesterol > 45 mg/dL

Pleural fluid protein > 2.9 g/dL

Question 18

How might you classify an effusion due to CHF as a transudate even if it meets normal criteria for an exudate and why?

Answer 18

Serum-pleural fluid albumin difference is >1.2 g/dL

Because protein is not truly leaking, serum is just relatively more concentrated due to diuresis in these patients

Question 19

What can cause a low protein pleural effusion with high glucose?

Answer 19

Peritoneal dialysis

-> high glucose content in diasylate fluid

Question 20

What connective tissue diseases can cause pleural effusion and is it a transudate or exudate?

Answer 20

Rheumatoid pleurisy, SLE pleuritis

-> exudate

Question 21

What do you base on your differential diagnoses on if nothing obviously gives you diagnosis of your pleural fluid?

Answer 21

Cell count: i.e. neutrophils, lymphocytes, eosinophils, RBCs

Glucose

pH

LDH

High amylase

Question 22

How do parapneumonic effusions (associated with pneumonia) typically resolve, and what is typical vs complicated?

Answer 22

Usually resolve spontaneously

Typical: pH>7.2, glucose >60, gram stain negative
-> not associated with loculation, Abx alone is fine

Complicated: pH <7.2, glucose <60, gram stain positive
-> chest tube and thrombolytics may be needed in addition as effusion becomes loculated

Question 23

What is empyema and what is the treatment?

Answer 23

A complication of parapneumonic effusion, frank pus is obtained by thoracentesis

Need antibiotics and chest tube, with probable surgery to prevent long-term sequellae

Question 24

What are the most common malignant effusions of the lungs? What will lymphocytes, glucose, LDH, and cytology show?

Answer 24

Lung or breast cancer

Lymphocytes - high
Glucose - low
LDH - high

Cytology - may be initially negative but does not rule out, repeat.

Question 25

If tuberculosis is highly suspected as causing effusion, but cannot be stained or cultured, what level is measured as a surrogate?

Answer 25

Adenosine deaminase level (>40 U/L minimum)

Question 26

What is diagnostic of hemothorax?

Answer 26

Hematocrit of pleural fluid is >50% of serum hematocrit

Question 27

What are the nontraumatic causes of hemothorax?

Answer 27

Anticoagulation, malignancy, aneurysm, thoracic endometriosis (very rare), spontaneous pneumothorax

Question 28

When is pleural biopsy done and how is it generally done nowadays?

Answer 28

If diagnosis remains unconfirmed after thoracentesis

Done via open biopsy by thoracic surgeons

Question 29

Why is tension pneumothorax a medical emergency? How is it diagnosed?

Answer 29

Can cause low blood pressure due to decreased venous return

diagnosis generally by CXR

Question 30

What is the difference between tension pneumothorax and spontaneous pneumothorax?

Answer 30

Spontaneous - much rarer, occurs in a patient without underlying disease, and air enters pleura from alveoli

Tension - generally due to trauma or iatrogenic, air enters pleura from thru chest will

Question 31

How do you treat small vs large pneumothorax?

Answer 31

Small - give patient O2 and monitor by CXR, nitrogen should reabsorb thru alveoli

Large - drain by chest tube. If acute cardiopulmonary collapse, use needle aspiration then chest tube

Question 32

How is recurrent pneumothorax treated?

Answer 32

Pleurodesis - inject talc into pleural space to create inflammation and closure of pleural space