Pleural effusion

Accumulation of fluid in the pleural cavity in an amount greater than 10ml. The free fluid can be of various natures. We usually distinguish: exudate, transudate, empyema, hemothorax a chylothorax.

Pathogenesis
It is usually related to the nature of the accumulated fluid.

Transudate
Is is a protein-poor liquid. It occurs when hydrostatic intravascular pressure increases or oncotic pressure decreases (hypoproteinemia). It ussually associated with systemic diseases. The most common causes are: congenstive heart failure (bilateral),nephrotic syndrome (bilateral) and liver cirrhosis (right).

Exudate

 * It usually arises in conection with pleural processes. It is a protein-rich liqiud. The pathogenesis is an increase in pleural permiability or a resorption disorder. It is important to distinguish between exsudates associated with an infectious or non-infectious process. Among infectious diseases we include mainly pneumonia. Non-infectious exsudates are found in pulmonary embolism, tumor processes (bronchogenic carcinoma, beast cancer, gastric cancer and malignant lymphoma) and less often in autoimmune systemic inflammation (SLE, rheumatoid arthritis).

Empyema usually arises as a complication of exudate in pneumonia. Hemothorax a chylothorax occur mainly during major traumas.

Clinical manifestation and diagnosis
The most common manifestation is shortness of breath, which is caused by compression of the lungs and limited function of the diaphragm and chest wall. The effusion irritates the pleura, leading to pleural pain and dry irritating cough. In the case of large effusions (tumor), the mediastinum and large vena cava can be compressed. This caused reduced right ventricular filling and reduced cardiac output.

Physical examination
By physical examination, we are able to detect effusions up to 300-400ml. At the site of effusion, there is weakened, even inaudible atrial respiration, darkened percussion, weakened bronchophony and fremitus pectoralis. Above the upper limit of the effusion, we can hear a band of weakened tubular breathing.

Imaging methos
The most improtant method is undoubtedly sonography, which detects effusion as low as 50-100ml. We also use it to identify fibrin septa and fluid compartments.

Skiagram of the chest shows effusions up to 200-300ml (blunt costophrenic angle) Up to 500ml of effusion can be detected in bedridden patients. Inflammatory effusions have an upper limit of parabolic shape with cranially directed convexity, in non-inflammatory this convexity is smaller.

We use CT a PET/CT to differentiate malignant pleural disorders

Pleural puncture
We do this when it is not a cardiac failure. We then analyze the punctate biochemically, cytologically and microbiologically


 * Biochemical examination
 * It involves the determination of total protein and LD, to distinguish transudate from exudate (Light's criteria). We also determine amylase (pancreatitis, esophageal rupture), glucose (rheumatoid effusion, bacterial effusion) and lipids (chylothorax).


 * Cytology
 * It shows the presence of erythrocytes (pulmonary embolism), tumor cells, polymorphonuclear cells (bacterial infections, pulmonary infection), monocytes (TB, rheumatoid arthritis) or eosinophils (asbestosis).


 * Mikrobiological examination
 * Includes Gram and Ziehl-Neelsen staining, aerobic, anaerobic, fungal and PCR cultivation.

Biopsy
In case of ambiguity we can perform a skiagram or sonographically guided percutaneous pleural biopsy. If we need a more accurate idea of the location of the disease, we perform videothoracoscopy with visually targeted pleural biopsy. We use this mainly for malignancies or tuberculosis of the pleura.

Therapy
First of all, we try to treat the root cause of pleural effusion. These can be either well controlled (pneumonia, cardiac failure, pulmonary embolism, liver cirrhosis with portal hypertension, etc.) or less difficult to control (disseminated tumors, asbestosis). If the primary causes cannot be further influenced, we try to reduce clinical manifestations. For this, we use single or repeated pleural punctures, or drainage, oxygen substitution and analgesics (especially opiate)

The most reliable method for preventing excessive production of the malignant effusions is pleurodesis with intrapleural application of sclerosing agents (talc, bleomycin) through the chest drain. A more effective but invasive method is surgery in the form of simple abrasion of the pleura with susequent application of talc pleurodesis.

Related articles

 * Puncture
 * Emergencies in pneumology
 * Pleural puncture (pediatrics)