PLEURAL EFFUSION
INTRODUCTION
There is normally a very thin layer of fluid (from 2 to
10 µm thick) between the two pleural surfaces, the
parietal pleura and visceral pleura.
 The pleural space and the fluid within it are not
under static conditions.
 During each respiratory cycle the pleural pressures
and the geometry of the pleural space fluctuate
widely. Fluid enters and leaves the pleural space
constantly.
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The serous membrane
covering the lung
parenchyma is called the
visceral pleura.
The remainder of the lining of
the pleural cavity is the
parietal pleura.
The parietal pleura receives
its blood supply from the
systemic capillaries.
The visceral pleura is
supplied predominantly by
branches of the bronchial
artery in humans
The lymphatic vessels in the parietal
pleura are in direct
communication with the pleural space by
means of stomas.
These stomas are the only route through
which cells and large particles can leave
the pleural space.
Although there are abundant lymphatics
in the visceral pleura, these lymphatics
do not appear to participate in the
removal of particulate matter from the
pleural space.
MECHANISM OF PLEURAL FLUID TURNOVER
Dependent on the hydrostatic and oncotic pressures across membranes.
When the capillaries in the parietal pleura are considered, it can be seen that the
net hydrostatic pressure favoring the movement of fluid from these capillaries to
the pleural space
is the systemic capillary pressure (30cm H2O) minus the
negative pleural pressure (-5cm H2O) or 35cm H2O.
Opposing this is the oncotic pressure in the blood (34cm H2O) minus the oncotic
pressure in the pleural fluid (5 cm H2O), or 29cm H2O.
The resulting net pressure differences of 6 cm H2O (35-29) favors movement of
fluid from the parietal pleura into the pleural space.
Parietal
Pleura
Pleura
Space
Visceral
Pleura
Hydrostatic Pressure
+30
-5
+ 24
35
6
29
0
29
29
Net
+ 34
+5
Oncotic Pressure
+34
NORMAL COMPOSITION PLEURAL FLUID
Volume
 Cells/ mm3
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Mesothelial cells
Monocytes
Lymphocytes
PMN’s
Protein
 LDH
 Glucose
 pH

0.2 mL/kg
1000 – 5000
60%
30%
5%
5%
1-2 g/dL
<50% plasma level
 plasma level
≥ plasma level
PATHOPHYSIOLOGY

Pleural fluid will accumulate when the rate of
pleural fluid formation is greater than the rate of
pleural fluid removal by the lymphatics.
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Pleural effusions have classically been divided into
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Transudative
Exudative
A transudative pleural effusion occurs when
alterations in the systemic factors that influence
pleural fluid movement result in a pleural effusion.
Ex. Heart failure, nephrotic syndrome, hepatic
cirhosis.
 Exudative pleural effusions occur when the pleural
surfaces are altered. Ex. Pleurisy.

ETIOLOGY
Elevated pleural capillary pressure :
Congestive heart failure, pericardial disease.
Elevated pleural permeability :
Pleural inflammation, neoplastic pleural disease
(metastatic disease or mesotheliomas), pulmonary emboli,
systemic lupus erythematosus (SLE).
Decreased serum oncotic pressure :
Cirrhosis, nephrotic syndrome, myxedema.
Dysfunction of parietal pleura lymphatics drainage.
Trauma, such as esophageal perforation, post-cardiac injury
syndrome.
CLINICAL FEATURES
Many patients have no symptoms due to the
effusion when effusion is small.
Pleuritic chest pain is the usual symptom of
pleural inflammation.
Irritation of the pleural surfaces may also result in a
dry, nonproductive cough.
With larger effusions, dyspnea results from lung
compression.
PHYSICAL EXAMINATION
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Signs are proportional to amount of effusion.
Fullness of intercostal spaces.
Decreased or absent tactile fremitus.
Dullness to percussion.
Diminished breath sounds over the site of the effusion.
Change in findings with change in position.
Signs of pneumonia like bronchial breathing,crackles
etc.
CHEST XRAY
The first fluid accumulates in the lowest portion of the thoracic
cavity, which is the posterior costophrenic angle.
The earliest radiologic sign of a pleural effusion is blunting of
the posterior costophrenic angle on the lateral chest
radiograph.
If a posteroanterior radiograph is obtained with the patient
lying on the affected side, free pleural fluid will gravitate
inferiorly and a pleural fluid line will be visible.
Pleural fluid is loculated when it does not shift freely
in the pleural space as the patient’s position is
changed.
Loculated pleural effusions occur when there are
adhesions between the visceral and parietal
pleurae.
Both ultrasound and computed tomography (CT)
have useful in making this differentiation.
USG THORAX
CT CHEST
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Should thoracentesis be performed?
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If thoracentesis is done
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Is the fluid a transudate or exudate?
If the fluid is an exudate
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What is the etiology?
SHOULD THORACENTESIS BE PERFORMED?
 Most

patients should be tapped
Newly recognized effusion.
 Two
exceptions
Small Effusions ( < 1 cm on decubitus)
 Congestive Heart Failure

Thoracentesis only if bilateral effusions not equal.
 Fever.
 Pleuritic chest pain.
 Impending respiratory faillure.
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Is The Fluid A Transudate Or Exudate?
 Transudative
Effusions
Mechanical
 No capillary leak or cytokine activation
 Excessive formation or impaired absorption
 Limits the differential with no additional workup
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CHF, Cirrhosis, or Nephrotic Syndrome
If Exudative, more investigation required
 Method: LIGHT’s Criteria
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LIGHT’S CRITERIA (EXUDATE)
 Pleural

Pleural total protein > 3g/dl.
 Pleural

fluid total protein/ serum protein >0.5
fluid LDH/serum LDH > 0.6
Pleural fluid LDH > 200 IU/l.
 Pleural
fluid LDH level > 2/3 of upper normal
level of serum LDH.
EFFUSIONS
Transudate
Exudate
Congestive Heart
Failure
 Nephrotic syndrome
 Cirrhosis
 Meig’s Syndrome
 Hydronephrosis
 Peritoneal Dialysis
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Parapneumonic
Malignancy
Pulmonary Embolism
Tuberculosis
Traumatic
Collagen Vascular (SLE,
RA)
Drug induced, Uremia,
Dressler’s syndrome
OTHER USEFUL TESTS
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Brain Natriuretric Peptide (N<1000 pg/mL)
 > 1000 in CHF
Glucose < 60 mg/dL
 Empyema or Rheumatoid Arthritis
pH < 7.2 Empyema
Triglycerides > 110 mg/dL
 Chylothorax
Amylase
 Malignancy, Pancreatic disease.
OTHER USEFUL TESTS

Pleural to blood Hct > 0.5
 Hemothorax
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Cell Count
 PMN predominate in parapneumonic pneumonia.
 Lymphocyte predominate in malignancy, Tb, CABG.
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The pleural fluid ADA level above 45 IU/L - tuberculous pleuritis.
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Fluid Culture
 Grams stain, bacterial culture, acid fast bacilli smear and culture,
and fungal culture.
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Cytology for malignancy.
PLEURAL FLUID MANAGEMENT
 Observation
 Defervesce quickly
 Uncomplicated pleural effusion
 Therapeutic drainage (thoracentesis)
 Early exudative phase
 Tube thoracostomy
 Complex pleural fluid spaces
 VATS (Video assisted thoracoscopic surgery)
 Poor clinical response to above interventions
 Decortication: removal of pleural peel
 Parapneumonic

Any pleural effusion associated with bacterial or
viral pneumonia
 Loculated

parapneumonic effusion
Not free flowing
 Multiloculated

effusion
parapneumonic effusion
Noncommunicating compartments
 Empyema
(fibrosuppurative exudate)
Pus in the pleural space.
 pH < 7.2, Glucose < 60 mg/dL, High LDH.
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