Pleural Diseases

Question 1

pleural effusion - defined

Answer 1

*an abnormal collection of fluid in the pleural space that is clinically detectable
*pleural effusions suggest pulmonary, pleural, or extrapulmonary disease
*results from an imbalance between fluid formation and removal

Question 2

pleural fluid formation & drainage

Answer 2

*pleural fluid flows in a horizontal direction, from costal to mediastinal regions
*pleural lymphatic flow mostly localized to diaphragm & mediastinal surfaces
*homeostatic balance between capillary filtration & lymphatic absorption (hydrostatic push and oncotic pull)

Question 3

pleural effusion: physical exam findings

Answer 3

*diminished breath sounds
*dullness to percussion
*decreased tactile fremitus

Question 4

pleural effusion: radiographic confirmatory studies

Answer 4

*ultrasound most common
*plain CXR (demonstrates costophrenic angle blunting, especially on lateral view)
*CT

note - PFTs would show decreased TLC and FVC (restrictive defect)

Question 5

pleural effusion: targeted history

Answer 5

ALWAYS INVESTIGATE:
*duration of the effusion
*previous pneumonia or pleurisy
*CABG surgery, esp. with harvesting of the internal mammary arteries
*history of radiation treatment
*remote asbestos exposure
*history of travel, residence

Question 6

thoracentesis for pleural effusion

Answer 6

*placement of a needle into the pleural space (without hitting the lung)
*can be used to treat pleural effusion by removing/reducing the lung
*can also be beneficial for diagnosis to examine the pleural fluid

Question 7

classifications of pleural effusions

Answer 7

1. transudative
2. exudative

Question 8

transudative pleural effusions

Answer 8

*clear fluid (hypocellular)
*results from alterations in systemic factors that influence movement of fluid in and out of the pleural space with a net accumulation of fluid
*due to INCREASED HYDROSTATIC PRESSURE and/or DECREASED ONCOTIC PRESSURE
*common causes: heart failure, liver disease, kidney disease

Question 9

exudative pleural effusions

Answer 9

*cloudy fluid (cellular)
*due to infection, malignancy, connective tissue disease, lymphatics, or trauma
*often requires drainage due to increased risk of infection
*common causes: pneumonia, malignant pleural disease, pulmonary embolism, and GI disease

Question 10

normal pleural fluid

Answer 10

*protein concentration about 15 g/L
*clear/light yellow
*< 500 nucleated cells/microliter (differential: 2% neutrophils, 0% basophils, 7-11% lymphocytes, 61-77% MACROPHAGES, 9-30% MESOTHELIAL CELLS)
*pH 7.45-7.60
*glucose equivalent to serum glucose level

Question 11

Light’s Criteria for categorizing transudative vs. exudative pleural effusions

Answer 11

*any one of the following is consistent with an exudative pleural effusion; all 3 increases the surety:
1. pleural fluid (PF) LDH > two-thirds of the upper limit of normal serum LDH (~170)
2. PF LDH / serum LDH ratio > 0.6
3. PF protein / serum protein ration > 0.5

Question 12

5 key pathophysiological mechanisms for pleural fluid accumulation

Answer 12

1. increased transpleural pressure (ex. CHF) - transudate
2. decreased oncotic pressure (ex. hypoalbuminemia, cirrhosis) - transudate
3. increased capillary permeability (ex. pneumonia) - exudate
4. impaired lymphatic drainage (ex. malignancy) - exudate
5. transdiaphragmatic movement of fluid from the pleural space (ex. hepatic hydrothorax) - transudate

Question 13

core studies for pleural effusions

Answer 13

*total protein
*LDH
*pH
*glucose
*gram stain with cultures
*cytology

Question 14

main pleural fluid chemistry: LDH

Answer 14

*helpful in assessing the degree of pleural inflammation
*helps to differentiate transudates from exudates
*increasing level implies progressive pleural inflammation and a decreasing level implies decreasing pleural inflammation

Question 15

main pleural fluid chemistry: glucose

Answer 15

• < 60 mg/dl implicates increased cell metabolism, as can be seen with active inflammation
  *TB, parapneumonic effusion, malignancy, or connective tissue disorders associated with low glucose

Question 16

quick DDx for transudative pleural effeusions

Answer 16

*changes in hydrostatic or oncotic pressure gradient
*most common causes:
-CHF with systemic venous hypertension
-atelectasis
-cirrhosis
-nephrotic syndrome
-hepatic hydrothorax

Question 17

transudative pleural effusion due to hepatic hydrothorax

Answer 17

*liver cirrhosis and portal hypertension without cardiac or pulmonary pathology
*most commonly right sided
*ascites traversing from peritoneal space to pleural space via diaphragmatic fenestrations & pressure gradient (peritoneal space = high pressure; pleural space = low pressure)

Question 18

transudative pleural effusion due to nephrotic syndrome

Answer 18

*excessive loss of plasma proteins in urine
-includes: hypoalbuminemia, hypercholesterolemia, & peripheral edema
*excretion of total proteins > 3.5 g/day

Question 19

quick DDx for exudative pleural effusions

Answer 19

*due to pleural inflammation, increased capillary permeability, or impaired lymphatic drainage
*most common causes:
-INFECTION
-MALIGNANCY
-immunologic/inflammatory disorders
-lymphatic disorders
-asbestos related

Question 20

exudative pleural effusion due to malignancy

Answer 20

*large, unilateral, bloody, exudative pleural effusion
*diagnostic yield of pleural fluid cytology = 66%

Question 21

exudative pleural effusion due to tuberculosis

Answer 21

*pleural fluid adenosine deaminase (ADA) level > 40
*lymphocyte/neutrophil ration > 0.75 (> 60% lymphocytes)

Question 22

exudative pleural effusion due to rheumatoid arthritis

Answer 22

*most common intrathoracic manifestation of rheumatoid arthritis
*typically pH < 7.20, glucose < 50 mg/dL, pleural serum/glucose ratio < 0.5, elevated LDH (>1000), rheumatoid titer > 1:320
*associated with rheumatoid nodules

Question 23

exudative pleural effusion due to systemic lupus erythematosus (SLE)

Answer 23

*SLE can commonly cause pleural effusion
*check ANA levels and look for presence of lupus cells

Question 24

exudative pleural effusion due to chylothorax

Answer 24

*appearance is turbid or milky, due to chyle in pleural space from thoracic duct obstruction
*pleural fluid TRIGLYCERIDE > 110 mg/dL (check chylomicrons)
*common causes: trauma (injury to thoracic duct) or malignancy (lymphoma)

Question 25

exudative pleural effusion due to cardiac injury

Answer 25

*post-CABG
*post-cardiac injury syndrome (Dressler’s):
- > 1 week after myocardial injury, with pericarditis, chest pain, fever, pulmonary infiltrates, friction rub
-pleural effusion is small, left-sided; hemorrhagic with acute neutrophil predominant exudate evolving to lymphocyte predominant
-improves with anti-inflammatory drug therapy

Question 26

DDx (top 3) for pleural fluid glucose < 60 mg/dL or pH < 7.2

Answer 26

1. malignancy
2. infection
3. rheumatoid arthritis

Question 27

management of transudative pleural effusions

Answer 27

*treat the organ that caused the effusion (ex. treat the heart, liver, or kidney)
*normally do not need to be drained

Question 28

4 indications for chest tube drainage of an exudative pleural effusion

Answer 28

1. frank pus comes out on thoracentesis
2. positive pleural fluid gram stain
3. positive pleural fluid culture
4. pleural fluid pH < 7.2

Question 29

pneumothorax (PTX) - defined

Answer 29

accumulation of air in the pleural space

Question 30

pneumothorax (PTX) classifications

Answer 30

1. spontaneous PTX
2. traumatic PTX
3. iatrogenic PTX
4. tension PTX

Question 31

primary spontaneous pneumothorax

Answer 31

*due to rupture of apical subpleural bleb or cyst
*occurs most frequently in tall, thin, young males
*associated with tobacco smoking

Question 32

secondary spontaneous pneumothorax

Answer 32

*due to diseased lung (e.g. bullae in emphysema, infections, Marfan syndrome) or mechanical vent with use of high pressures, leading to barotrauma

Question 33

traumatic pneumothorax

Answer 33

*caused by blunt (ex. rib fracture) or penetrating (ex. gunshot) trauma
*may or may not include bronchial rupture

Question 34

tension pneumothorax

Answer 34

*air enters pleural space but cannot exit; increasing trapped air leads to tension pneumothorax
*intrathoracic pressure becomes SUPRA-ATMOSPHERIC (higher than atmospheric pressure)
*trachea deviates AWAY FROM affected lung
*needs immediate needle decompression and chest tube placement
*risk factors:
-receiving positive pressure mechanical ventilation
-undergoing CPR
-spontaneous pneumothorax left untreated

Question 35

pneumothorax - clinical presentation

Answer 35

*tactile fremitus is absent
*percussion note demonstrates hyperresonance
*breath sounds are reduced or absent on affected side
*trachea may be shifted toward the contralateral side if the pneumothorax is large

Question 36

needle decompression

Answer 36

*used to emergently relieve a tension pneumothorax
*needle thoracostomy can be performed on the affected side at the 5th intercostal space midaxillary line
*midclavicular line through the 2nd intercostal space with a readily available kit

Question 37

chest tube - location for placement

Answer 37

*“triangle of safety”
*borders:
-axillary fold
-pectoralis major border
-nipple/5th intercostal space