Pleural effusion

It is the abnormal accumulation of fluid in the pleural space. The pleural space is the space between the lungs and the thoracic cavity and under normal conditions there is a minimum amount of fluid inside.

In the case of accumulation of blood it is called hemothorax, and in the case of accumulation of pus, empyema.

How it is produced

It occurs when there is a mismatch between the production of liquid and its reabsorption. The amount of fluid in the pleural space cannot be more than 15 ml. Otherwise, the pleural effusion appears.

Depending on the type, the characteristics of the pleural fluid are classified as:

1- Transudates: it is the result of an increase in intravascular pressure, or the oncotic pressure of the blood or a combination of both. They are liquids with a low concentration of protein and cholesterol, and with low densities.

They occur mainly in: heart failure (the most frequent cause of transudates), constrictive pericarditis, fluid overload, superior vena cava syndrome, liver cirrhosis, nephrotic syndrome and peritoneal dialysis.

2- Exudates: they are produced by an increase in the permeability of the pleural surface, generally due to inflammatory causes. Exudates can have different origins: infections (parapneumonic as the most frequent cause of exudates), cancer, metastases, pulmonary thromboembolisms, pancreatitis, connective tissue diseases (rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, Wegener's granulomatosis) drugs (Nitiorofurantoin, Metrorexate, Ammonia) drugs , metronidazole) and radiotherapy among the most frequent.

Symptoms

Pleural effusion usually presents as chest pain with pleuritic characteristics, that is, by localized, sharp and intermittent pain that increases with coughing and deep inspiration. It can be associated with a dry cough and fever in the case of exudates.

Its most characteristic signs are hydric dullness on percussion, bulging of the hemithorax on inspection, and decreased transmission of vocal vibrations and vesicular murmurs on auscultation. In some cases, a plural murmur can also be heard, due to alveolar compression of the underlying lung.

Diagnosis

After a complete medical history that includes a thorough anamnesis (interrogation) and physical examination to try to know the cause of the pleural effusion, an imaging test such as a chest X-ray is necessary, initially in anteroposterior projection and in case of doubts diagnostic, in lateral decubitus projection on the affected side to see if the fluid is displaced. The most common radiological image is the effacement of the posterior costophrenic angle (angle between the chest wall and the diaphragm) and the most typical image, the "Damoisseau" meniscus.

In some cases in which more information is required, ultrasound or pulmonary CT can be performed, especially in those cases in which there is underlying lung disease.

When the pleural effusion is very important, it can displace the mediastinum due to the pressure of the fluid. These complementary imaging techniques help determine this shift.

To determine the origin of the effusion, diagnostic thoracentesis is performed, which is a puncture through the thorax to obtain a sample of pleural fluid for analysis. In cases of small effusions and in those that appear in the context of congestive heart failure or cirrhosis without fever, this diagnostic technique can be avoided.

Thoracentesis allows the analysis of the fluid in different parameters:

• biochemicals: glucose, proteins, triglycerides, cholesterol, LDH, pH
• cytological: hematocrit and leukocytes
• microbiological: aerobic and anaerobic cultures, GRAM staining

and thus to be able to classify it in transudate or exudate to know the cause of it.

Treatment

It is aimed at solving the underlying disease that has caused the pleural effusion. In cases of pleural effusion caused by heart failure, the treatment of the cause (in this case diuretics) is the one of choice. In cases of massive and / or symptomatic effusions, a therapeutic thoracentesis is usually necessary, which consists of aspiration of the fluid with a needle or with the placement of a chest drainage tube.

Malignant pleural effusions are treated with chemotherapy or radiotherapy, and in some cases by performing a chemical pleurodesis that consists of the instillation between both pleurae of chemical substances in order to obliterate the pleural space and prevent fluid from accumulating inside.

Pleural effusion secondary to pneumonia (parapneumonic) usually responds to treatment with systemic antibiotics. In case of pleural effusions after complicated pneumonia (complicated parapneumonic or empyema), it requires the placement of a chest drainage tube for its resolution.

Hemothorax: It is the accumulation of blood in the plural space. The most frequent cause is traumatic, which can be produced accidentally or iatrogenic by means of some invasive diagnostic maneuver or spontaneously. Clinically, it presents as acute onset chest pain with hypotension and anemia. The chest radiograph shows a partial or total opacity of the affected hemithorax and thoracentesis is the one that will confirm the diagnosis. Treatment is aimed at treating the underlying disease and evacuating the hemothorax through a drainage tube. In severe cases, a thoracotomy may be necessary.