CPC 3 - Pleural Effusion Flashcards
What is the mechanism of pleural fluid?
Increased hydrostatic pressure; Decreased oncotic pressure; Increased permeability of pleura; Increased pulmonary interstitial fluid; Movement from other cavities (peritoneal); Vascular rupture into thorax; Rupture of thoracic duct.
What do you do once you have identified pleural effusion as a transudate?
Treat the cause
What do you do if patient returns to clinic after being treated for pleural effusion?
Pleural aspiration and send fluid for: Biochemistry Microbiology Cytology Flow cytometry
What criteria must be met for pleural fluid to qualify as exudate?
Lights Criteria
Pleural fluid is an exudate if one or more of the following criteria are met:
Pleural fluid protein divided by serum protein is >0.5;
Pleural fluid lactate dehydrogenase (LDH) divided by serum LDH is >0.6;
Pleural fluid LDH >2/3 the upper limits of laboratory normal values for serum LDH
What is the difference between exudate and transudate?
Pleural fluid protein >30 g/l has indicated an exudate and
What can pleural fluid NT-proBNP be used for?
Pleural fluid NT-proBNP correlates with blood NT-proBNP, level of >1500 shown to discriminate cardiac failure from other causes of transudative effusions
What can pleural fluid pH be used for?
pH
What can pleural fluid glucose be used for?
Low level
What can amylase in pleural fluid indicate?
Useful in suspected cases of oesophageal rupture or effusions associated with pancreatic diseases
What can mesothelin, Fibulin-3, and Osteopontin levels in pleural fluid indicate?
All independently shown to help differentiate malignant from non malignant pleural effusions in patients with asbestos exposure
What are potential organisms that can be present in pleural fluid that are community acquired?
Strep spp. (52%)
Staph aureus (11%)
Gram -ve aerobes (9%) (enterobacteriaceae, E. Coli)
Anaerobes (20%) (Fusobacterium spp., Bacteroides spp., Peptostreptococcus spp., mixed)
What are potential organisms that can be present in pleural fluid that are hospital acquired?
Staphylococci (MRSA - 25%; S. aureus - 10%)
G-ve aerobes (17%) (E. coli, Pseudomonas aeruginosa, Klebsiella spp.)
Anaerobes (8%)
What are the cytology/characteristics of pleural effusion due to acute inflammation?
Mainly neutrophils
Usually underlying pneumonia
Frank pus indicates empyema
Reactive mesothelial cells may mimic malignancy
What are the cytology/characteristics of pleural effusion due to eosinophilic effusion?
> 10% eosinophils
Usually a reaction to air or blood in the pleural space
Rarer causes include: drug reactions; parasite infection; pulmonary infection; Churg-Strauss syndrome
What are the cytology/characteristics of pleural effusion due to lymphocytic effusion?
Mainly lymphocytes Broad differential diagnosis Inflammatory disease (eg. rheumatoid) Infection (including mycobacterial) Malignancy (solid or lymphoma) Others (after CABG)
What are the cytology/characteristics of pleural effusion due to malignant effusion?
Primary or secondary
Solid or haematological
use immunohistochemistry to define cell type
Definitive diagnosis or mesothelioma rarely possible
Squamous cell carcinoma may not shed cells into fluid
What does pleuritic chest pain indicate?
Inflammation or irritation of the parietal pleura.
The parietal pleura contains sensory nerve endings that can detect pain.
What are the basic functions of pleura?
Pleural fluid originates in parietal pleural tissue.
The parietal pleura and visceral pleura glide over each other without separation.
The visceral pleura absorbs fluid, which then drains into the lymphatic system and returns to the blood.
The pleural space typically contains 10-20ml of fluid at one time.
What is the definition of pleural effusion?
The accumulation of fluid the the pleural space. It occurs whenever the rate of fluid formation and rate of resorption are mismatched.
What imaging of CXR is used to confirm presence of pleural effusion?
PA and lateral CXR.
Look for homogenous density, density in dependent portion (costophrenic angle in PA view), Meniscus sign (dense homogenous opacity with a concave upper border; higher laterally than medially), loss of normal silhouette (obscures hemidiaphragm), +/- mediastinal shift.
What is lost from view on a CXR in 50 ml, 175-200ml, and 500ml pleural effusion? What view is this seen in?
50ml - lateral view, obliteration of anterior or posterior CP angle
175-200ml - PA view, obliteration of lateral CP angle
500ml - PA view, obliteration of ipsilateral hemidiaphragm
What is a loculated effusion?
When the fluid does not shift freely in the pleural space, usually due to adhesions between the visceral and parietal pleura (eg. haemothorax, infection (empyema))
No change by gravitational positioning
Lentiform opacity against chest wall (convex to the lung)
May mimic chest wall mass
What to do once location of pleural effusion has been established?
Investigate aetiology, cause may be obvious from the clinical history or radiographic findings
Generally, all patients with unilateral plerual effusion (>1 cm in height on lateral decubitus X-ray, US or CT) of unknown origin should have thoracentesis
What is a subpulmonic effusion?
When pleural fluid is located in the subpulmonic region in upright patients. lung floats on a layer of fluid.
The hemidiaphragm is flattened and inverted, without significant blunting of lateral costophrenic angle.
Apparent elevation of hemidiaphragm;
Lateral peak of hemidiaphgragm;
2cm between hemidiaphragm and gastric bubble
Can be confirmed by Decubitus film (lying down)
What are the advantages of using US in imaging pleural effusions?
Lack of ionising radiation
Low cost and easy to repeat
Real-time bed side applications
Best method to detect small pleural effusions (from 5 ml)
More sensitive than CT to depict the internal structure (septa) of pleural collections.
Anechoic US appearance of pleural effusions
US finding: Echo-free (black) spaces between pleural layers
Suggests transudate, sometimes exudate
Complex non septated US appearance of pleural effusions
US finding: Echogenic material (bright) in anechoic fluid
Suggests exudate
Complex septated US appearance of pleural effusions
Fibrin strands or septa floating in anechoic fluid
Suggests exudate
Echogenic US appearance of pleural effusions
Homogeneously echogenic fluid
Suggests exudate, haemorrhage, empyema or chylothorax
What are the advantages of CT for imaging pleural effusions?
Differentiates pleural from parenchymal lesions
Determines the precise location and extent of pleural disease
Differentiates between free and loculated fluid
More sensitive than US for differentiating fluid from pleural thickening
Exact placement of chest tubes and percutaneous biopsy
What should be done before a CT of pleural effusion?
Administer contrast medium, and CT should be performed before complete aspiration of fluid (pleural abnormalities will be better visualised)
What are common causes of exudative pleural effusions?
Parapneumonic effusion
Malignant neoplasm
What are common causes of transudative pleural effusions?
Heart failure
Cirrhosis
Hypoalbuminemia
Peritoneal dialysis
What are less common causes of exudative pleural effusions?
Pulmonary infarction RA Benign effusion related to asbestos Pancreatitis Dressler's syndrome Autoimmune disease
What are less common causes of transudative pleural effusions?
Nephrotic syndrom PE Mitral stenosis Atelectasis Hypothyroidism
Congestive cardiac failure and pleural effusion?
Most common cause of transudative effusions.
Most often are bilateral (R>L).
If unilateral, are most commonly right-sided.
Usually, associated cardiac enlargement, with or without pulmonary venous hypertension.
Effusions improve quickly once diuretic therapy is started.
What are CXR findings for congestive heart failure?
Heart enlarged Pleural effusions Upper lobe diversion Kerley B lines \+/- Enlarge central pulmonary arteries Also fissural fluid collections
What percentage of pleural effusions in older patients are malignant?
25%
Malignant effusions details?
The pleura may be involved by primary or secondary tumours
Secondary tumours account for about 90% of pleural neoplasms
Tumoral invasion of the pleura is produced by haematologic route, lymphatic invasion or by contiguity spread
What is the appearance of malignant effusions on CXR?
Unilateral pleural effusion
Unilateral nodular/irregular pleural thickening
Rib destruction
What is the appearance of malignant effusions on CT?
Nodular pleural thickening
Mediastinal pleural thickening
Parietal pleural thickening > 1cm
Circumferential pleural thickening
What are the clinical features that are suggestive of malignant origin of pleural effusion?
Symptoms > 1m
Absence of fever
Blood-tinged fluid
Chest CT suggesting malignancy
What are the primary sites causing metastatic pleural effusion?
Lung>breast>lymphoma/leukemia
Metastatic adenocarcoma positive cytology (70%);
Lymphoma (25-50%);
Squamous cell carcinoma (20%);
Sarcoma within pleura (25%).
