PANCE Blueprint Pulmonary (10%)

Pleural effusion (ReelDx)

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Pleural Effusion

68 y/o female with 6 months of bilateral chest pain and difficulty breathing

Patient presents as → a 58-year-old female who returns to the hospital with chest pain and difficulty breathing several weeks after being discharged following a myocardial infarction requiring immediate cardiac catheterization. She has been coughing up frothy sputum for the past three days. The patient complains of a sharp pain that worsens during inspiration. Physical exam reveals decreased tactile fremitus, dullness to percussionand diminished breath sounds on the left side. Chest X-ray demonstrates blunting of the left costophrenic angle, meniscus sign, obliteration of the left hemidiaphragm, and mediastinal shift.

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What criteria are used to differentiate between exudative and transudative pleural effusions?
Light’s criteria are used to differentiate between exudative and transudative pleural effusions.

A pleural effusion is a pathologic accumulation of fluid in the pleural space (often associated with pneumonia)

Dullness to percussion—In pleural effusions, percussion over the affected area is dull. This is because fluid in the pleural space absorbs the sound waves during percussion, resulting in a dull sound instead of the normal resonant sound heard over air-filled lung tissue.

Decreased tactile fremitus—Tactile fremitus refers to the palpable vibration of the chest wall that results from the transmission of sound vibrations through the lung tissue to the chest wall

  • Pleural effusion presents with decreased tactile fremitus because the presence of fluid in the pleural space dampens the transmission of sound vibrations from the lung to the chest wall
Decreased tactile fremitus Increased tactile fremitus
Decreased intensity of tactile fremitus may occur as a result of the following:

Increased intensity of tactile fremitus generally occurs as a result of increased density within the lung tissue

Transudative vs. Exudative Pleural Effusions

  • Transudate = think “transient” fluid due to hydrostatic pressure (cirrhosis, CHF, nephrotic syndrome)
    • The most common causes of transudative effusions are heart failure, cirrhosis with ascites, and hypoalbuminemia (usually due to nephrotic syndrome)
  • Exudative = fluid due to infection (pneumonia), malignancy, immune

Light's criteria: If at least one of the following three criteria is present, the fluid is defined as an exudate

Basically, ↑ Protein and ↑ LDH = Exudative

  • Pleural fluid protein/serum protein ratio > 0.5
  • Pleural fluid LDH/serum LDH ratio greater than 0.6
  • The pleural fluid LDH is greater than two-thirds the upper limit of normal for serum LDH

“It's all about that LDH"

Light Criteria for Pleural Effusion Transudate Exudate
Pleural:serum protein ≤ 0.5 > 0.5
Pleural:serum LDH ≤ 0.6 > 0.6
Pleural fluid LDH ≤ 2/3 upper limit of normal serum LDH > 2/3 upper limit of normal serum LDH
Primary causes
  • Heart failure
  • Cirrhosis
  • Nephrotic syndrome
  • Pulmonary embolism
  • Malignancy
  • Bacterial/viral pneumonia
  • Tuberculosis
  • Pulmonary embolism
  • Pancreatitis
  • Esophageal rupture
  • Collagen vascular disease
  • Chylothorax/hemothorax

Evaluation requires imaging (usually chest x-ray) to confirm the presence of fluid and pleural fluid analysis to help determine the cause

  • lateral decubitus chest X-ray and upright films
    • A large free pleural effusion appears as a dependent opacity with lateral upward sloping of a meniscus-shaped contour at the junction of the lung and the diaphragm (meniscus sign). The diaphragmatic contour is partially or completely obliterated, depending on the amount of the fluid (silhouette sign)
  • Chest CT or ultrasonography should be done if it is unclear whether an x-ray density represents fluid or parenchymal infiltrates or whether the suspected fluid is loculated or free-flowing
  • Thoracentesis is performed for diagnostic and therapeutic purposes, with analysis of pleural fluid (e.g., protein, LDH, cell count, pH, glucose) to differentiate between transudative and exudative effusions

Physical exam: decreased tactile fremitus and dullness to percussion would be found in a pleural effusion

  • In pleural effusions, vocal fremitus is decreased
  • In pleural effusions, breath sounds are decreased
  • Isolated left-sided pleural effusion is likely exudative
  • Right-sided think transudative
Pleural effusion

Pleural effusion seen on lateral decubitus chest x-ray. Arrow A shows fluid layering in the right pleural cavity. The B arrow shows the normal width of the lung in the cavity.

Treatment is with thoracocentesis

  • Small transudative pleural effusions resulting from heart failure may be treated with diuretics and sodium restriction
  • Effusions that are chronic or recurrent and causing symptoms can be treated with pleurodesis (pleural space is artificially obliterated) or by intermittent drainage with an indwelling catheter

osmosis Osmosis
Picmonic
Light’s Criteria

IM_MED_Lightscriteria_V1.3_

Light’s Criteria is a diagnostic tool used to determine if the cause of a pulmonary effusion; transudate versus exudate. This relies on a comparison of the chemistries in the pleural fluid to those in the blood. According to Light’s criteria, a pleural effusion is likely exudative if at least one of the following exists: The ratio of pleural fluid protein to serum protein is greater than 0.5, the ratio of pleural fluid LDH and serum LDH is greater than 0.6, or the pleural fluid LDH is greater than 0.6 or 2⁄3 times the normal upper limit for serum.

Play Video + Quiz

Question 1
On physical examination you note diminished breath sounds over the right lower lobe with decreased tactile fremitus and dullness to percussion. Which of the following is the most likely cause?
A
asthma
Hint:
Asthma is characterized by decreased tactile fremitus, but would have resonant to hyperresonant percussion, not dullness.
B
consolidation
Hint:
Consolidation from pneumonia is characterized by dullness to percussion, but would have an increased, not decreased, tactile fremitus.
C
pneumothorax
Hint:
A pneumothorax is characterized by decreased to absent tactile fremitus, but would have a hyperresonant percussion note, not dullness.
D
pleural effusion
Question 1 Explanation: 
A decreased tactile fremitus and dullness to percussion would be found in a pleural effusion.
Question 2
Which of the following conditions will produce a transudative pleural effusion?
A
Kaposi's sarcoma
Hint:
Kaposi's sarcoma, pneumonia, or mesothelioma will produce a transudative pleural effusion.
B
Pneumonia
Hint:
See A for explanation.
C
Cirrhosis
D
Mesothelioma
Hint:
See A for explanation.
Question 2 Explanation: 
Transudative pleural effusions result from alteration in the formation of pleural fluid, the absorption of pleural fluid, or both, by systemic factors. Local factors affecting pleural fluid absorption and/or formation produce
Question 3
A 42 year-old male is brought to the emergency department with a stab wound to his right lateral chest wall. On physical examination, the patient is stable with decreased breath sounds on the right with dullness to percussion. An upright chest x-ray reveals the presence of a moderate pleural effusion. Subsequent diagnostic thoracentesis contains bloody aspirate. Which of the following is the next most appropriate intervention?
A
Thoracotomy
Hint:
A thoracotomy is indicated in a small percentage of patients that do not respond to IV administration of fluids and evacuation of the hemothorax via tube thoracostomy. (u) B. Needle aspiration as treatment for a hemothorax is not recommended as it fails to adequately drain the bloody fluid.
B
Needle aspiration
Hint:
Needle aspiration as treatment for a hemothorax is not recommended as it fails to adequately drain the bloody fluid.
C
Close observation
Hint:
Close observation is only indicated for small effusions in a patient that remains hemodynamically stable.
D
Tube thoracostomy
Question 3 Explanation: 
This patient has a hemothorax. Drainage of a hemothorax is best obtained through insertion of a chest tube (tube thoracostomy).
Question 4
A 60-year-old female with a 30-pack year smoking history complains of new onset shortness of breath. On physical examination, dullness is noted on percussion with diminished breath sounds over her left base. Chest x-ray shows a new left pleural effusion. Which of the following is the next step in the management of this patient?
A
Repeat chest x-ray in two months
Hint:
See B for explanation.
B
Perform diagnostic thoracentesis
C
Order MRI of the chest
Hint:
See B for explanation.
D
Treat with antibiotic
Hint:
See B for explanation.
Question 4 Explanation: 
Diagnostic thoracentesis should be performed whenever there is a new pleural effusion and no clinically apparent cause.
Question 5
Which of the following physical examination findings would be most consistent with a pleural effusion?
A
Hyperresonance to percussion
Hint:
Hyperresonance to percussion would be suggestive of emphysema or pneumothorax
B
Increased tactile fremitus
Hint:
Increased tactile fremitus would be consistent with a consolidation.
C
Unilateral lag on chest expansion
D
Egophony
Hint:
Though egophony may be present with pleural effusion it is only heard above the level of the effusion in an upright patient. The presence of egophony would be most consistent with consolidation.
Question 5 Explanation: 
A lag on chest expansion may be seen in the presence of a pleural effusion.
Question 6
A 45-year-old man presents to the emergency department with shortness of breath and pleuritic chest pain. A chest x-ray reveals a large left-sided pleural effusion. Thoracentesis is performed and the fluid is sent for analysis. Which of the following results would be most consistent with an exudative effusion according to Light’s criteria?
A
Pleural fluid protein/serum protein ratio < 0.5
Hint:
A pleural fluid protein/serum protein ratio less than 0.5 would be consistent with a transudative effusion.
B
Pleural fluid LDH/serum LDH ratio < 0.6
Hint:
A pleural fluid LDH/serum LDH ratio less than 0.6 would be consistent with a transudative effusion.
C
Pleural fluid cholesterol < 45 mg/dL
Hint:
Pleural fluid cholesterol is not one of Light’s criteria for differentiating between exudative and transudative effusions.
D
Pleural fluid protein/serum protein ratio > 0.5
E
Pleural fluid LDH < two-thirds the upper limit of normal for serum LDH
Hint:
A pleural fluid LDH less than two-thirds the upper limit of normal for serum LDH would be consistent with a transudative effusion.
Question 6 Explanation: 
Light’s criteria are used to differentiate between exudative and transudative pleural effusions. An exudative effusion is present if any one of the following criteria is met:
  • The pleural fluid protein/serum protein ratio is greater than 0.5
  • The pleural fluid LDH/serum LDH ratio is greater than 0.6
  • The pleural fluid LDH is greater than two-thirds the upper limit of normal for serum LDH
Therefore, answer choice D is correct.
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References: Merck Manual · UpToDate

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