What Is the Etiology of Pleural Effusion?

Pleural effusion is a common clinical feature characterized by the accumulation of pathological fluid in the pleural cavity. The pleural cavity is a potential gap between the visceral layer and the parietal pleura. Normal people have 5 to 15 ml of liquid in the pleural cavity, which acts as a lubricant during breathing exercises. 500 to 1000 ml of liquid is formed and absorbed in the pleural cavity every day. Any The reason is that the pleural cavity produces more fluid or decreases its absorption, which can produce pleural effusion. According to its mechanism, it can be divided into two types: leaky pleural effusion and exudative pleural effusion.

Basic Information

nickname

Pleural fluid

English name

pleural effusion

Visiting department

Respiratory Medicine

Multiple groups

young people

Common symptoms

heat

Contagious

no

Causes of pleural effusion

Increased hydrostatic pressure in pleural capillaries (such as congestive heart failure), increased pleural permeability (such as pleural inflammation, tumors), decreased osmotic pressure of pleural capillaries (such as hypoproteinemia, cirrhosis), and parietal layers Pleural lymphatic reflux disorders (such as cancerous lymphatic obstruction) and chest injury can cause pleural effusion. Common clinical causes are as follows:

Leaking pleural effusion

Pleural effusions caused by congestive heart failure, constrictive pericarditis, cirrhosis, superior vena cava syndrome, nephrotic syndrome, glomerulonephritis, dialysis, and myxedema are often leaked.

2. Exudative pleural effusion

(1) Malignant pleural tumors include primary mesothelioma and metastatic pleural tumor.

(2) Infection of the chest cavity and lungs such as tuberculosis and other bacterial, fungal, viral, and parasitic infections.

(3) Connective tissue diseases such as systemic lupus erythematosus, polymyositis, scleroderma, sjogren's syndrome.

(4) Lymphocyte abnormalities such as multiple myeloma and lymphoma.

(5) Drug-induced pleural diseases such as minoxidil, bromocriptine, ergometrine, methotrene moaning, levodopa and so on.

(6) Digestive system diseases such as viral hepatitis, liver abscess, pancreatitis, esophageal rupture, diaphragmatic hernia.

(7) Other hemothorax, chylothorax, uremia, endometriosis, radiation injury, post-myocardial infarction syndrome, etc.

Clinical manifestations of pleural effusion

Symptoms

(1) The symptoms are not obvious when there is less pleural effusion and less effusion (less than 300ml), but when the amount of effusion in the early stage of acute pleurisy is small, there may be obvious chest pain. When the effusion increases, the visceral layer of the pleura is separated from the parietal layer, and chest pain can be reduced or disappeared. When there is a moderate or large amount of pleural effusion (greater than 500ml), shortness of breath, chest tightness, palpitations, dyspnea, and even sitting breath with cyanosis can occur.

(2) Patients with primary symptoms such as pleural effusion caused by tuberculosis may have symptoms of tuberculosis such as low fever, fatigue, and consumption; patients with heart failure have symptoms of cardiac insufficiency; pneumonia-related pleural effusion and pus and blood often have fever and cough Sputum; liver abscess in patients with liver pain.

2. Signs

Patients with fibrinous pleurisy can hear pleural friction or touch pleural friction. During moderate and large effusions, it can be seen that the affected side has limited breathing movements, shallow breathing, full intercostal space, tracheal displacement to the healthy side, weakened or disappeared voice tremor on the affected side, and increased respiratory sounds above the effusion area, which can sometimes be heard Bronchial breathing sound.

Pleural effusion

Imaging examination

(1) The general effusion volume of chest X-ray and chest CT can be seen to be dull in the costal angle. Encapsulated effusion is limited to one place and does not change with changes in body position. Chest CT can show the fluid, but also the lung, mediastinum, and pleural lesions, which can prompt the cause of the fluid.

(2) Thoracic ultrasound The echoless area between the pleural viscera and the parietal layer that can change with breathing is a feature of pleural effusion ultrasound examination. Thoracic ultrasound can estimate the amount of effusion, and can also identify pleural effusion, pleural thickening, fluid pneumothorax, and so on. The cystic effusion can provide a more accurate localization diagnosis and is helpful for pleural puncture and aspiration.

2. Thoracentesis

(1) Appearance.

(2) Examination of specific gravity, qualitative mucin, protein content and cell number.

(3) Glucose and pH: Determination of pleural glucose content can help identify the cause of pleural effusion.

(4) Enzymes: Determination of enzyme activities such as lactate dehydrogenase, amylase, adenosine deaminase, etc., used to distinguish between leakage and exudate, or to distinguish malignant pleural effusion and tuberculous pleural effusion.

(5) Lipids: The determination of lipids in effusion helps to distinguish chylothorax and pseudochylothorax.

(6) Bilirubin: Measuring the ratio of pleural effusion to serum bilirubin (greater than 0.6) is helpful for the diagnosis of exudate.

(7) Pathogen: Pleural fluid smear to find bacteria and culture, which is helpful for the diagnosis of pathogens.

3. Percutaneous pleural biopsy

Percutaneous pleural biopsy under the guidance of B ultrasound or CT is of great significance for the diagnosis of the etiology of effusion.

4. thoracoscopy or open chest biopsy

For those who cannot be diagnosed by the above examination, if necessary, biopsy can be performed through thoracoscopy or open thoracotomy, which is the most direct and accurate method for diagnosis and treatment of pleural effusion.

Diagnosis of pleural effusion

First, determine the presence of pleural effusion based on clinical symptoms, signs, and imaging. Then identify the nature of the pleural effusion, which is to distinguish between the leaked fluid and the exudate. Finally, according to the accompanying symptoms, the results of various tests, and the scope of the etiology involved in the leakage or exudate, further find evidence and clarify the cause.

Treatment of pleural effusion

Once the diagnosis is clear, treatment for different conditions should be performed. In order to reduce symptoms, a certain amount of pleural fluid is drawn when necessary to reduce the symptoms of dyspnea in patients.

Tuberculous pleural effusion

Most patients are satisfied with antituberculosis treatment. A small amount of pleural fluid generally does not require aspiration or diagnostic puncture. Thoracocentesis not only helps diagnosis, but also relieves lung, heart, and blood vessel compression, improves breathing, prevents fibrin deposition and pleural thickening, and prevents lung function from being damaged. After pumping, the symptoms of toxicity can be reduced and the patient's temperature can be reduced. A large amount of pleural fluid can be pumped 2 to 3 times a week until the pleural fluid is completely absorbed. The amount of fluid per pump should not exceed 1000 ml. Too fast or too much fluid can cause a sudden drop in chest pressure, pulmonary edema or circulatory disturbances, manifested as severe cough, shortness of breath, a lot of foamy sputum, and full lungs. Wet rales, PaO ₂ decreased, and chest X-ray showed pulmonary edema. At this time, oxygen should be taken immediately, glucocorticoids and diuretics should be used as appropriate, control the amount of water, and closely monitor the condition and acid-base balance. If there is a "pleural reaction" that appears to be dizziness, cold sweat, palpitations, pale, thin pulses, and cold limbs during pumping, stop pumping immediately and place the patient supine. If necessary, inject 0.1% epinephrine 0.5ml subcutaneously Closely observe the condition, pay attention to blood pressure, and prevent shock. In general, it is not necessary to inject drugs into the chest cavity after pleural fluid is drawn.

Glucocorticoids can reduce the body's allergic and inflammatory reactions, improve symptoms of toxicity, accelerate pleural fluid absorption, reduce pleural adhesions or pleura thickening. However, there are certain adverse reactions or tuberculosis spread, so the indications should be carefully grasped. Acute tuberculous exudative pleurisy has severe systemic toxicity symptoms, and those with more pleural fluid can add glucocorticoids, usually prednisone or prednisolone, to antituberculous drugs. When the patient's temperature is normal, systemic toxicity symptoms are reduced or subsided, and pleural fluid is significantly reduced, the amount should be gradually reduced or even stopped. The withdrawal rate should not be too fast, otherwise the phenomenon of rebound may occur, and the general course of treatment is 4 to 6 weeks.

2. Pneumonia-related pleural effusion and empyema

The principle of treatment is to control infection, drain pleural effusion, and promote lung expansion and restore lung function. For the pathogenic bacteria of empyema, effective antibacterial drugs should be applied as soon as possible, and administered systemically and intrathoracically. Drainage is the most basic treatment for empyema, which can be repeated pumping or closed drainage. The chest cavity can be repeatedly flushed with 2% sodium bicarbonate or physiological saline, and then infused with appropriate amounts of antibiotics and streptokinase to thin the pus and facilitate drainage. A few empyema can be inserted into the intercostal drainage tube and connected to a water seal bottle to drain the pleural effusion. For those with bronchopleural fistula, it is not advisable to flush the chest cavity to avoid spreading bacteria.

When patients with chronic empyema have pleural thickening, thoracic collapse, chronic attrition, clubbing fingers (toes) and other symptoms, surgical pleural excision should be considered. In addition, general supportive care is also very important. Foods with high energy, high protein and vitamins should be given. Correct water and electrolyte disorders and maintain acid-base balance, if necessary, a small amount of blood transfusion can be given.

3. Malignant pleural effusion

Therapeutic pleural aspiration and pleural fixation are common methods for the treatment of malignant pleural effusion. Due to the rapid and persistent growth of pleural effusion, patients often have severe breathing difficulties due to the compression of a large amount of effusion, and even cause death. Therefore, repeated thoracentesis is needed for this type of patients. However, repeated pumping can cause too much protein loss (1 liter of pleural fluid contains 40 grams of protein), so the treatment is very difficult and the effect is not ideal. For this reason, the correct diagnosis of malignant tumors and tissue types, and the timely and effective treatment are of great significance for alleviating symptoms, reducing pain, improving quality of life, and prolonging life. Systemic chemotherapy has a certain effect on pleural effusion caused by some small cell lung cancer. Local radiotherapy is available for patients with mediastinal lymph nodes. After aspiration of pleural fluid, injecting anti-tumor drugs including doxorubicin, cisplatin, fluorouracil, mitomycin, nitrcamole, bleomycin, etc. into the chest cavity is a commonly used treatment method. This helps kill tumor cells, slows down the production of pleural fluid, and can cause pleural adhesions. Injecting biological immune modulators into the chest cavity is a more successful method for exploring malignant pleural effusion in recent years, such as Corynebacterium vaccine (CP), IL-2, interferon beta, interferon gamma, and lymphokine-activated killer cells (LAK Cells), tumor infiltrating lymphocytes (TIL), etc., can inhibit malignant tumor cells, enhance the local infiltration and activity of lymphocytes, and cause pleural adhesion. In order to close the pleural cavity, pleural adhesion agents such as tetracycline, erythromycin, and talc can be injected after the pleural fluid is drained with a thoracic cannula to prevent the adhesion of the two layers of pleura to prevent the pleural fluid from forming again. If a small amount of lidocaine and dexamethasone are injected at the same time, it can reduce the adverse reactions such as pain and fever.

4. Leaky pleural effusion

For the leakage of pleural effusion, the primary disease is mainly treated. After the primary disease is controlled, the effusion usually disappears on its own. When the large volume of fluid causes obvious clinical symptoms or the treatment of the primary disease is not effective, the symptoms can be relieved by closed chest drainage.