What are the causes of pleural effusion?
Transudate protein <30 g/L
Exudative protein >30 g/L
Exudate protein (>30g/L) causes? - (6) (24)
1) Neoplasia
Carcinoma of the lung
Secondary malignancy (breast, ovarian, pancreatic, and GI)
Mesothelioma
Lymphoma
Meig’s Syndrome (ovarian fibroma, ascites, and pleural effusion)
2) CTD
SLE
RA
3) Infection/Lung
Pneumonia
TB
Pulmonary Infarction
4) Sub-diaphragmatic
Pancreatitis
Sub-phrenic Abscess
Hepatic Abscess
5) Drugs
Practolol (Beta 1 antagonist)
Procarbazine (oral chemo HL)
Bromocriptine
Methotrexate
Nitrofurantoin
6) Other
Asbestosis
Sarcoidosis
Dressler’s Syndrome
Trauma
Oesophageal Rupture (Borehave’s syndrome)
Yellow Nail Syndrome (Yellow Nails’
Yellow Nails, Pleural Effusions, Lymphadema
Chylothorax)
Transudate protein (<30g/L) causes? (8)
Congestive Heart Failure
Constrictive pericarditis (reduced filling/venous congestion of lungs)
Hypoalbuminemia
Nephrotic Syndrome
Cirrhosis
Peritoneal dialysis
( Increased intra-abdominal pressure from the dialysate forces fluid through small, often congenital, diaphragmatic defects.)
Uraemia (increased vascular permeability from uremic toxins)
Hypothyroidism
- Increased Capillary Permeability: The lack of thyroid hormone alters capillary permeability, allowing albumin to leak into the pleural cavity.
- Myxedema/Mucopolysaccharide Deposition: Hypothyroidism causes the extravasation of mucopolysaccharides into interstitial spaces and body cavities, which raises osmotic pressure and draws fluid in. Lack of T3 interferes with normal metabolism, allowing acid mucopolysaccharides to build up in the intercellular matrix.
What volume of pleural fluid can be detected as a pleural effusion on a chest radiograph?
180 mL
Earliest sign = loss of costophrenic angle on AP view or
50 mL loss of clear definition of diaphragm posteriorly on lateral view
How would you confirm the suspicion of a small pleural effusion?
Use lateral decubitis view (accumulates as a layer along dependent chest wall, unless loculated)
If layering of fluid is 1cm = pleural effusion > 200 mL
Or
Use USS
How is USS useful in context of pleural effusion? (5)
1) Detection of small pleural effusions
2) Diagnosis of loculated pleural effusion
3) Guiding pleural fluid aspiration or drainage
4) Guide pleural biopsy
5) Differentiate pleural fluid from pleural thickening
What is the appearance and composition of normal pleural fluid? (6)
1) Clear ultrafiltrate of plasma
2) pH = 7.60 - 7.64
3) Protein <1-2 g/L (<2%)
4) WCC < 1000/mm3
5) LDH <50% of plasma concentration
6) Glucose similar to plasma concentration
What is the pathophysiology of a pleural effusion?
Normal pleural space contains 1 mL of fluid representing balance between hydrostatic and oncotic forces in the visceral and parietal pleural vessels and extensive lymphatic drainage
Small amount of fluid enters → lymphatics remove it → steady ~1 mL maintained
Pleural effusions = disruption of this balance
Mechanisms of pleural effusion and examples? (6-3,3,7,2,2,2)
1) Altered permeability of pleural membranes → Inflammation, neoplasia, pulmonary embolism (PE)
2) Reduced intravascular oncotic pressure → Hypoalbuminemia, cirrhosis, nephrotic syndrome
3) Increased capillary permeability or vascular disruption → Trauma, inflammation, neoplasia, infection, uraemia, pancreatitis, drug hypersensitivity
4) Increased capillary hydrostatic pressure → CHF, SVC obstruction
5) Decreased lymphatic drainage → Trauma, Malignancy
6) Increased fluid in peritoneal cavity and migration across diaphragm via lymphatics → Peritoneal dialysis, cirrhosis
What are lights criteria for an exudate?
1) The ratio of pleural fluid to serum protein is greater than 0.5
2) The ratio of pleural fluid to serum LDH is greater than 0.6
3) The pleural fluid LDH value is greater than two-thirds of the upper limit of the lab normal serum value
One criteria need to be met
In patients receiving chronic diuretic therapy, what precautions must be taken when interpreting pleural fluid results?
Chronic diuretic therapy increases protein and LDH concentration in pleural fluid to exudative range
In this situation, use:
Serum protein-effusion protein gradient, if <31g/L then this more correctly identifies an exudate
What is the differential diagnosis of dullness and dull percussion note at a lung base? (6)
1) Pleural effusion
2) Pleural thickening
3) Collapse
4) Consolidation
5) Raised hemidaphragm
6) Lower lobe lobectomy (need thoracotomy scar - look at back)
If pleural fluid LDH level > 1000 IU/L what would that suggest? (4)
And what’s a lung cavity?
1) Empyema
2) Malignant Effusion
3) Rheumatoid Effusion
4) Pleural Paragonimiasis
Paragonimus westermani = endemic disease in asia, through ingestion of raw freshwater crayfish or crabs
Can have pulmonary infiltrates, cavities, nodules and pleural effusion
Cavity = an abnormal, thick-walled (typically >5 mm), air-filled space within the lung parenchyma, often formed by tissue necrosis and drainage through the airways
What are the causes of a haemorrhagic pleural effusion? (4)
1) Malignancy
2) PE
3) TB
4) Chest Trauma
How would you diagnose a chylothorax? (3)
1) Milky-white appearance of pleural fluid
2) Pleural fluid cholesterol >4g/L
3) TG raised
What are the causes of a chylothorax? (3)
1) Lymphatic obstruction (lymphoma or solid tumours)
2) Lymphatic damage (post cardiothoracic surgery/trauma)
3) Yellow Nail Syndrome
What are the causes of low glucose concentration in pleural fluid? (6)
1) Malignancy
2) TB
3) Empyema
4) Oesopageal rupture
5) RA
6) SLE
What are the causes of low pH of pleural fluid?
Same causes as for low glucose (if pleural fluid <7.3) - low pH correlates well with low glucose
What are the causes of an elevated amylase in pleural fluid? (4)
1) Pancreatitis
2) Malignancy
3) Bacterial pneumonia
4) Oesophageal rupture
What is the significance of a low pH (<7.3) in the context of a malignant pleural effusion? (4)
1) More extensive pleural involvement
2) Higher yield on cytology
3) Decreased success rate of pleurodesis
4) Shorter life expectancy
How reliable is pleural fluid biochemistry and microbiology in the diagnosis of tb pleuritis?
TB pleural effusions = hypersensitivity rx to mycobacterium, not bacterial invasion so acid-fast bacillus stain <10% of cases
Pleural fluid cultures grow Mycobacterium TB in 65% of cases
Pleural tissue biopsy + culture increase diagnostic yield to 90%
ADA (adenosine deaminase activity) >43 U/L = support dx but sensitivity is 78% so if less doesn’t exclude pleuritis
Interferon-gamma concentration >140 pg/mL support tb pleuiritis but not routinely available
How would you investigate a patient with pleural effusion? (11 - tons of stuff)
1) Blood Tests
FBC (Leukocytosis)
U&Es
LFTs
Inflammatory markers
Serum Albumin + Lipid
Serum LDH
Serum Amylase
TFTs
RF
Autoimmune Profile (ANA,ENA,ANCA)
2) CXR
3) ABG
4) Pleural Tap
Protein, LDH glucose, and pH
Amylase (pancreatitis, oesophageal rupture, or malignancy)
Cytology
MC&S
Cholesterol (Chylothorax)
Cytology
Ziehl-Neelson staining and mycobacterial culture (tb)
RF & Ana
5) Pleural Biopsy (TB/Malignacy)
6) CTPA (if PE suspected)
7) CT Chest (lung malignancy/lymphoproliferative disorder is suspected)
8) Bronchoscopy (malignancy)
9) ECHO (Cardiac Failure)
10) Mammogram (if breast primary suspected)
11) CT Abdomen (lymphoproliferative, GI, or renal malignancy)
What are the complications of pleural fluid drainage? (4)
1) Pneumothorax
2) Haemothorax
3) Hypovolemia
4) Unilateral Pulmonary Edema
What are the indications for pleuroadesis? (3)
1) Recurrent malignant pleural effusion
2) Recurrent pneumothoraces
3) Recurrent benign effusions (e.g. hepatic hydrothorax)
