Pleural effusion

Introduction We often say that pleural effusion is actually pleural effusion. Normal people have 3 to 15 ml of liquid in the pleural cavity, which acts as a lubricant during respiratory movement, but the amount of fluid in the pleural cavity is not fixed. Even in normal people, 500 to 1000 ml of liquid is formed and absorbed every 24 hours. The pleural fluid is reabsorbed from the venous end of the capillaries, and the rest of the fluid is recovered from the lymphatic system to the blood, and the filtration and absorption are in dynamic equilibrium. If this dynamic balance is destroyed by systemic or local lesions, the fluid in the pleural cavity is formed too fast or absorbed too slowly, and pleural effusion (referred to as pleural effusion) is clinically produced.

Cause

Causes of pleural effusion

1. Increased hydrostatic pressure in the pleural capillaries.

2. Increased pleural capillary permeability.

3. The osmotic pressure of the pleural capillaries is reduced.

4. Parietal pleural lymphatic drainage disorder cancer.

5. Intrathoracic hemorrhage caused by injury.

an examination

Related inspection

Chest B-cardiopulmonary exercise test (CPET) Lung biopsy pleural effusion examination M-mode echocardiography (ME)

Appearance

The leakage liquid is clear and clear, and it is not solidified after standing, and the specific gravity is <1.016~1.018. The exudate is mostly straw yellow and slightly turbid, with a specific gravity of >1.018. Purulent pleural fluid is often smelly if it is infected with E. coli or anaerobic bacteria. Bloody pleural effusion with different degrees of washing water or venous blood samples; milky pleural effusion is chylothorax; if the pleural fluid is chocolate, the amebic liver abscess may be considered to break into the chest; black pleural fluid may be aspergillosis .

2. Cell

There are a small number of mesothelial cells or lymphocytes in normal pleural effusion. When pleural inflammation occurs, various inflammatory cells and hyperplastic and degenerate mesothelial cells can be seen in the pleural fluid. The number of leaking cells is often less than 100 × 106 / L, mainly lymphocytes and mesothelial cells. The leukocytes of the exudate often exceed 500 × 106 / L. At the time of empyema, the white blood cells are as much as 1000×106/L or more. Neutrophils suggest acute inflammation; lymphocytes are mostly tuberculous or malignant; eosinophils often increase in parasitic infections or connective tissue diseases. When the red blood cells in the pleural fluid exceed 5 × 109 / L, it may be light red, mostly caused by malignant tumors or tuberculosis. Thoracic puncture damage to blood vessels can also cause bloody pleural fluid, which should be carefully identified. Trauma, tumor or pulmonary infarction should be considered when red blood cells exceed 100 × 109 / L. About 60% of malignant pleural fluid can be found in malignant tumor cells, and repeated examinations can increase the detection rate. Malignant tumor cells in pleural fluid often have nuclear enlargement and different sizes, nuclear aberrations, deep nuclear staining, abnormal nucleoplasmic ratio and abnormal mitotic division, which should be identified. The pleural fluid intermediate cells are often deformed and easily misdiagnosed as tumor cells. Non-tuberculous pleural fluid intermediate cells are more than 5%, and tuberculous pleural fluid is often less than 1%. When systemic lupus erythematosus is complicated by pleural effusion, the anti-nuclear antibody titer in the pleural fluid can reach above 1:160, and it is easy to find lupus cells.

3.pH

Tuberculous pleural fluid pH <7.30; pH <7.00 only found in empyema and pleural effusion caused by esophageal rupture. The pH of the pleural fluid caused by acute pancreatitis is <7.30; if the pH is <7.40, malignant pleural fluid should be considered.

4. Pathogens

Chest smears for bacteria and culture help pathogen diagnosis. Tuberculous pleurisy after pleural fluid deposition for tuberculosis culture, the positive rate is only 20%, chocolate pus should be microscopic examination of amoeba trophozoites.

5. Protein

The protein content of the exudate, pleural fluid / serum ratio greater than 0.5. When the protein content is 30 g/L, the specific gravity of the pleural fluid is about 1.018 (1 g per protein added and subtracted, so that it is increased or decreased by 0.003). The leakage protein content is low (<30g/L), mainly albumin, and the mucin test (Rivalta test) is negative.

6. Carcinoembryonic antigen (CEA)

Elevated CEA levels in malignant pleural fluid appeared earlier and more pronounced than serum. If the CEA value of the pleural fluid is >15~15g/L or the pleural fluid/serum CEA>1, it is often suggested as malignant pleural effusion. Increased ferritin content in malignant pleural effusion may be a reference for differential diagnosis. Combined detection of multiple markers can increase the positive detection rate.

7. Lipid

The content of neutral fat and triglyceride in the pleural fluid is higher (>4.52mmol/L), which is milky and turbid. Sudan III is dyed red, but the cholesterol content is not high, which can be seen when the thoracic duct is ruptured. "Cigar-like" or cholesterol pleural effusion (cholesterol > 2.59mmol / L), associated with the accumulation of old effusion cholesterol, can be seen in old tuberculous pleurisy, malignant pleural effusion or cirrhosis, rheumatoid arthritis. Cholesterol pleural fluid contains high levels of cholesterol, but triglycerides are normal, pale yellow or dark brown, containing cholesterol crystals, fat particles and a large number of degenerative cells (lymphocytes, red blood cells).

8. Glucose

The glucose content in the pleural fluid of normal people is similar to the glucose content in the blood, and changes with the rise and fall of blood glucose. Determination of glucocorticol content helps identify the cause of pleural effusion. The glucose content of the leakage fluid and most exudates is normal; and the glucose content in tuberculous, malignant, rheumatoid arthritis and suppurative pleural effusion can be <3.35mmol/L. If the pleural lesions are widely distributed, it is difficult for glucose and acidic metabolites to penetrate the pleura, which may result in lower glucose content, suggesting that the tumor is extensively infiltrated, and the rate of malignant tumor cells in the pleural fluid is also high.

9. Enzyme

The pleural fluid lactate dehydrogenase (LDH) content increased, greater than 200U / L, and pleural fluid LDH / serum LDH ratio greater than 0.6, suggesting that exudate, pleural fluid LDH activity can reflect the degree of pleural inflammation, the higher the value, It shows that the inflammation is more obvious. It is often suggested that a malignant tumor or pleural fluid has been complicated by a bacterial infection.

Elevated pleural fluid amylase can be found in acute pancreatitis, malignant tumors, and the like. In acute pancreatitis with pleural effusion, amylase leakage causes the enzyme to be higher in serum than in serum. Some patients have severe chest pain and difficulty breathing, which may mask their abdominal symptoms. At this time, the pleural fluid amylase has increased, and clinical diagnosis should be noted.

Adenosine deaminase (ADA) is high in lymphocytes. In tuberculous pleurisy, cytotoxicity is stimulated and lymphocytes increase significantly, so ADA in pleural fluid can be higher than 100 U/L (generally no more than 45 U/L). Its sensitivity in the diagnosis of tuberculous pleurisy is higher.

10. Immunological examination

With the advancement of cell biology and molecular biology, immunological examination of pleural fluid has attracted attention. It plays a role in the identification of benign and malignant pleural fluids, the study of the pathogenesis of pleural effusion and the future development of pleural effusion. In tuberculous and malignant pleural effusions, T lymphocytes increased, especially in tuberculous pleurisy, which was up to 90%, and mainly T4 (CD+4). The T cell function in malignant pleural effusion is inhibited, and its cytotoxic activity against autologous tumor cells is significantly lower than that of peripheral blood lymphocytes, suggesting that the local immune function of the thoracic layer is inhibited in patients with malignant pleural effusion. In patients with systemic lupus erythematosus and rheumatoid arthritis, the contents of complement C3 and C4 in pleural effusion decreased, and the content of immune complexes increased.

11. pleural biopsy

Percutaneous pleural biopsy can help to identify the presence or absence of tumors and to determine pleural granulomatous lesions. When the tuberculosis is to be diagnosed, the biopsy specimen can be used for tuberculosis culture in addition to pathological examination. Patients with empyema or bleeding tendency should not be used for pleural biopsy. A biopsy can be performed via a thoracoscope if necessary.

12. Ultrasound examination

Can identify pleural effusion, pleural thickening, liquid pneumothorax and so on. The cystic effusion can provide a more accurate positioning diagnosis, which is helpful for thoracic puncture drainage.

13. Tumor markers

Carcinoembryonic antigen (CEA) can be elevated early in malignant pleural effusion and is more pronounced than serum. If pleural fluid CEA>20ug/L or pleural fluid/serum CEA>1, it is often suggested as malignant pleural effusion with sensitivity of 40%-60% and specificity 70%-88%. Compared with CEA, pleural telomerase assay has greater sensitivity and specificity than 90%. In recent years, many tumor marker tests, such as sugar chain tumor-associated antigen, cytokeratin 19 fragment, and neuron-specific enolase, have been developed as reference for differential diagnosis. Combined detection of multiple markers can increase the positive detection rate.

14. pleural biopsy

Percutaneous closed pleural biopsy is important for the diagnosis of pleural effusion, and tumors, tuberculosis and other pleural granulomatous lesions can be found. When the tuberculosis is to be diagnosed, the biopsy specimen should be used for tuberculosis culture in addition to pathological examination. Pleural acupuncture biopsy has the advantages of simple, easy, and less invasive, and the positive diagnosis rate is 40%-75%. Biopsy guided by CT or B-ultrasound can improve the success rate. Patients with empyema or bleeding tendency should not be used for pleural biopsy. If the biopsy is confirmed to be malignant pleural mesothelioma, radiotherapy should be performed within the biopsy site within 1 month.

15. Thoracoscopic or open chest biopsy

For those who cannot be diagnosed by the above examination, biopsy may be performed under thoracoscopy or thoracoscopic surgery if necessary. Since 87% of pleural metastatic tumors are in the visceral layer and 47% are in the parietal layer, this test has positive significance. Thoracoscopy has the highest diagnostic rate for malignant pleural effusion, reaching 70%-100%, providing a basis for the proposed treatment plan. Thoracoscopy can comprehensively examine the pleural cavity, observe the morphological features, distribution range and involvement of adjacent organs, and can be biopsied under direct vision. Therefore, the diagnosis rate is higher and the clinical stage of the tumor is more accurate. Although the etiology of a small number of pleural effusions in clinical practice is still difficult to determine through the above-mentioned various examinations, if there is no special contraindication, a thoracotomy can be considered.

16. Bronchoscopy

This test is feasible for those who have hemoptysis or suspected airway obstruction.

Differential diagnosis

1. When the imaging diagnosis of pleural effusion volume is 0.3-0.5L, the X-ray only sees the rib angle become dull; more effusion shows the effusion shadow of the upper edge of the outer and upward arc. The effusion spreads when lying down, which reduces the brightness of the entire lung field. The liquid pleural effusion has a liquid level. When the effusion is large, the entire affected side is dark and the mediastinum is pushed to the healthy side. The effusion often has a smooth and full edge that is confined between the leaves or between the lungs and the ankle. Ultrasound is helpful for diagnosis.

2, B-ultrasound can explore the lumps covered by the pleural fluid, to assist in the positioning of thoracic puncture. CT examination can be judged as exudate, blood or pus according to the different density of pleural fluid. It can also show mediastinum, paratracheal lymph nodes, intrapulmonary masses, pleural mesothelioma and intrathoracic metastatic tumors. CT examination of pleural lesions has a higher sensitivity and density resolution. It is easier to detect a small amount of effusion that is difficult to display on the X-ray film.

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