Pleural effusion

Pleural effusion is the accumulation of fluid in the pleural cavity. The reasons for effusions can be very diverse, so they are usually classified as transudates or exudates. Identify in the physical examination and radiography of chest organs; Puncture of the pleural cavity with subsequent study of the pleural fluid often allows you to determine the cause of the effusion. Asymptomatic transudates do not require treatment. On the contrary, transudates, accompanied by clinical symptoms, and almost all exudates require performing pleural puncture, draining, pleurodesis and / or pleurectomy.

Normally, between 10 and 20 ml pleural fluid, similar in composition to blood plasma, but with a lower protein content (<1.5 g / dl) is finely distributed between the visceral and parietal pleura. This is necessary to facilitate movements between the lung and chest wall. The fluid enters the pleural cavity from the blood capillaries of the parietal pleura and is excreted into the pleural lymph vessels. Accumulation of the pleural fluid occurs when it reaches a significant extent in the pleural cavity or if it is too slowly removed from there.

[1], [2], [3], [4], [5], [6], [7], [8], [9]

Epidemiology

According to several studies, pleural effusion is diagnosed in more than 20% of patients in the ICU. Pleural effusion rarely serves as an independent cause of hospitalization of patients in the ICU (except for cases of massive pleural effusion with severe dyspnea), this condition develops as a complication of various diseases. So, with pneumonia pleural effusion is recorded in 40-60% of cases, with PE - in 40%, with congestive heart failure in 50% of cases. Also, pleural effusion is found in 7-27% of patients with HIV infection hospitalized in a hospital.

Pleural effusion can occur as a result of several mechanisms, including increased permeability of pleural sheets, an increase in pressure in the pulmonary capillaries, a decrease in negative intrapleural pressure, a reduction in the oncotic pressure of the blood plasma, and obstruction of the lymphatic drainage pathways.

Normally, the pleural cavity contains no more than 30 ml of fluid, and the total production of fluid is about 0.3 ml / kg per day. The appearance of pleural effusion indicates the presence of a serious extrapulmonary pathology or pathology of the lungs. Under normal conditions, the drainage system of the pleural cavities can cope with a more than 20-fold increase (about 700 ml) of fluid flow into the pleural cavity. Since differential diagnosis includes a wide range of diseases, the physician should provide a systematic approach to examining such a patient to establish the correct diagnosis as soon as possible, producing a minimum number of invasive examinations.

[10], [11], [12], [13], [14], [15], [16], [17]

What causes pleural effusion?

Pleural effusions have many causes and are usually divided into transudates or exudates based on the results of their laboratory studies. The transudate can usually be treated without a thorough examination, whereas the cause of the exudate needs clarification. Bilateral effusions usually have similar characteristics.

Causes of pleural effusion

Causes	Comments
Heart failure	Two-sided (81%), right-sided (12%), left-sided (7%). Left ventricular failure increases interstitial pressure, leading to fluid transudation and pleural effusion
Cirrhosis of the liver with ascites (hepatic hydrothorax)	Right-hand (70%); left-sided (15%); bilateral (15%). Ascetic fluid migrates into the pleural cavity through diaphragmatic defects; occurs in approximately 5% of patients with clinically evident ascites
Nephrosis	Occurs infrequently. Bilateral in more than 90% of cases; decrease in intravascular oncotic pressure causes transudation into the pleural cavity; is associated with edema or anasarka in other areas
Hydronephrosis	Usually bilateral, often sublegical; reduction of intravascular oncotic pressure in combination with hypervolemia leads to transudation into the pleural cavity
Syndrome of the superior vena cava	Urine spreads retroperitoneally into the pleural cavity, resulting in the development of urinothorax
Constrictive pericarditis	Malignant neoplasms or thrombosed central catheters block the intrathoracic lymphatic duct
Atelectasis	Hydrostatic pressure in veins increases; in some cases accompanied by a massive anasarka; the mechanism is similar to hepatic hydrothorax
Peritoneal dialysis	Increases the negative intrapleural pressure. The mechanism is similar to hepatic hydrothorax; Pleural fluid has characteristics similar to dialysate
Brief Light	The formation of a fibrous capsule leads to an even greater decrease in intrapleural pressure
Syndrome of systemic increase in capillary permeability	Occurs rarely in combination with an ansarca and effusion into the pericardial cavity
Myxedema	Occurs about 5%; transudate, if there is also an effusion in the pericardial cavity; However, with isolated pleural effusion, there may be both exudate and transudate
Pneumonia (parapneumonic exudate)	It can be uncomplicated, divided into several fragments and / or purulent (empyema); for the purpose of differential diagnosis it is necessary to perform a pleural puncture
Malignant neoplasms	Most often, lung cancer, pleural mesothelioma and breast cancer, but effusion can occur with any tumor metastasizing to the pleura; chest pain, usually dull and persistent
Pulmonary embolism	It occurs in about 30% of cases; almost always exudate; hemorrhagic - less than 50%; suspicion of thromboembolism occurs with dyspnea, not proportional to the volume of effusion
Viral infection	Exudation, usually minor, accompanied by a parenchymal infiltrate or without it; Systemic symptoms prevail, not lung manifestations
Aortocoronary bypass surgery	Left-sided or larger left (73%); bilateral, equal in volume (in 20%); right or more to the right (7%). In 10% of cases, more than 25% of the volume of the chest is filled within 30 days after the operation; hemorrhagic effusions are associated with postoperative hemorrhage and are resolved; nonhemorrhagic effusions recur, their cause often remains unknown
Tuberculosis	An effusion, usually one-sided or from the side of the parenchymal infiltrate; is caused by a hypersensitivity reaction to the protein of the mycobacterium tuberculosis; The causative agent is sown when cultivated in less than 20% of cases.
Sarcoidosis	Exudation is noted in 1-2% of cases; patients have extensive parenchymal lesions and often damage tissues outside the chest; In the pleural fluid, lymphocytes predominate
Uremia	Exudation is noted in approximately 3% of cases; more than 50% of patients have clinical manifestations, usually a rise in body temperature (50%), chest pain (30%), cough (35%) and dyspnea (20%); diagnosis is established by excluding other probable causes
Subdiaphragmatic abscess	Causes a sympathetic postoperative effusion; neutrophils predominate in pleural fluid, but pH and glucose concentration are normal
HIV infection	There are several possible causes: parapneumonic, tubercular, Kaposi's sarcoma, pneumonia caused by Pneumocystis jiroveci (formerly called P. Carinii) and other opportunistic infections
Rheumatological diseases	A typical patient is an elderly person with rheumatoid nodules and deforming arthritis; must differentiate from parapneumonic effusion
Systemic lupus erythematosus	It may be the first manifestation of SLE; often observed with drug SLE; The diagnosis is established by the results of serological tests of blood, but not pleural fluid
Side effect of drug therapy	Many drugs can induce the development of pleural effusion, most often, bromocriptine, dantrolene, nitrofurantoin, interleukin-2 (used for the treatment of renal cell carcinoma and melanoma), and methyl ester. Also occurs with drug lupus
Ovarian hyperstimulation syndrome	It complicates the induction of ovulation by human chorionic gonadotropin (hCG) and, sometimes, clomiphene; effusion develops 7-14 days after the administration of hCG; In 52% of cases right-sided effusion is noted, in 27% - bilateral
Pancreatitis	Acute: occurs in approximately 50% of cases; bilateral (77%); left-sided (16%); right-sided (8%). It is the result of trans-diaphragmatic spread of inflammatory exudate and inflammation of the diaphragm. Chronic: due to the penetration of pancreatic pseudocysts through the diaphragm into the pleural cavity; the clinical manifestations from the chest side, not the abdominal cavity, dominate, the patients visually appear to be oncological patients
Esophagus rupture	The patient is in extremely serious condition; an emergency condition; the development of complications and lethality are caused by infection of the mediastinum and pleural cavity
Simple asbestosis	Occurs more than 30 years after the initial exposure; often asymptomatic, tends to increase and disappear; it is necessary to exclude mesothelioma
Ovarian tumors (Meig's disease)	The mechanism is similar to hepatic hydrothorax; Not all patients with ovarian tumors with ascites and pleural effusions are inoperable
Syndrome of yellow nails	Triad of pleural effusion, lymphatic edema and yellow nails; Individual elements of the syndrome can appear for several decades apart; pleural fluid has a relatively high protein content, but a low concentration of LDH; effusion tends to recur, there is no pleural pain in the chest

Transudate is formed by the combination of increased hydrostatic pressure and reduced oncotic pressure in a small or large circle of blood circulation. The most frequent cause of this condition is heart failure, less often it is due to cirrhosis of the liver with ascites and hypoalbuminemia, usually a result of nephrotic syndrome.

Exudate is caused by local processes leading to an increase in the permeability of capillaries, which as a result leads to sweat through their wall of fluid, protein, cells and other components of blood plasma. The causes are numerous, the most frequent are pneumonia, malignant neoplasms, pulmonary embolism, viral infections and tuberculosis. The syndrome of yellow nails is a rare disease that causes chronic exudative pleural effusions, lymphatic edema and dystrophic changes of the nails when they become yellow; all manifestations are considered the result of impaired drainage function of lymphatic vessels.

Chylous exhalation (chylothorax) is a milky white effusion with a high triglyceride content, caused by traumatic or tumoral (most often, lymphomatosis) damage to the thoracic duct.

Lymph-like (cholesterol or pseudo-cholus) effusion resembles a painful effusion, but has a low triglyceride content and high cholesterol. Lymph-like effusions probably develop due to the release of cholesterol from lysed red blood cells and neutrophils with long-term effusions, when the absorption of effusion is disturbed by thickening of the pleura.

Hemotorax is the presence of a hemorrhagic fluid (the pleural fluid has a hematocrit of more than 50% of the same value of peripheral blood) in the pleural cavity, resulting from trauma or, rarely, as a result of coagulopathy or rupture of large blood vessels (eg, aorta or pulmonary artery).

Empyema - the presence of pus in the pleural cavity. It can be a complication of both pneumonia, thoracotomy, abscess (lung, liver or subdiaphragmatic), and penetrating trauma. Subsequently, the spread of pus in the soft tissue, leading to infection of the chest wall and external drainage of the purulent focus.

The armored lung is a lung, enclosed in a fibrous casing (armor), due to empyema or a tumor. Since the lung can not straighten, the pressure in the pleural cavity is further reduced, which increases the fluid's exudation from the parietal pleural capillaries. Fluid characteristics are at the boundary between the transudate and exudate, including biochemical parameters - within 15% of the diagnostic values of the Light criteria.
Iatrogenic effusions can be caused by migration or displacement of a nutrient or central venous catheter, which results in ingestion of food or intravenous solutions into the pleural cavity.

Exudations without obvious cause (idiopathic) develop often due to mute pulmonary embolism, tuberculosis or malignant neoplasms. Etiology is not established in approximately 15% of cases even after a thorough examination; Many of these effusions are believed to be the result of viral infections.

Symptoms of pleural effusion

Some pleural effusions are asymptomatic and are found by chance during a physical examination or chest radiography. Many cause dyspnea and / or pleural pain in the chest. Pleurisic pain, vague discomfort or acute pain in the chest, increasing in inspiration, indicate inflammation of the parietal pleura. Pain is usually felt in the area of inflammation, but the posterior and peripheral parts of the diaphragmatic pleura are innervated by more than six lower intercostal nerves, and irritation in these areas may be accompanied by pain in the lower sections of the thorax or abdominal cavity, sometimes simulating abdominal cavity diseases. Irritation of the central part of the diaphragmatic pleura, innervated by diaphragm nerves, causes pain radiating to the neck and shoulder.

Physical examination reveals the absence of vocal tremor, dullness with percussion and a decrease in respiratory noise on the effusion side. These signs can also be a consequence of a thickening of the pleura. With large volume effusions, breathing is usually frequent and superficial. The noise of friction of the pleura, although infrequent, is a classic physical sign. Its severity can vary from a small number of unstable sounds resembling crackling to intense intense hard friction, creaking or the sound of wrinkled skin, which coincide with breathing and can be heard on inhaling and exhaling. Friction, which is heard in the precordial region (pleuropericardial noise), can change with cardiac contractions and erroneously be taken as a pericardial friction noise. The latter is best heard on the left border of the sternum in the III and IV intercostal spaces as a characteristic biphasic sound synchronous with cardiac contraction and not largely dependent on respiration. The sensitivity and specificity of physical examination when finding an effusion is low.

Parapneumonic effusion and pleural empyema

About 55% of all cases of pneumonia requiring hospitalization of patients in the hospital, accompanied by the formation of effusion in the pleural cavity. The severity of the course of parapneumonic pleural effusions varies considerably - from uncomplicated effusion to the development of pleural empyema. Some forms of parapneumonic effusion do not require special therapy, except the appointment of antibacterial drugs, while in complicated pleurisy often perform a surgical intervention. Conditionally, in the process of formation of parapneumonic effusion, three stages are distinguished: uncomplicated parapneumonic effusion, complicated parapneumonic effusion, empyema of the pleura.

Uncomplicated parapneumonic effusion is a sterile neutrophilic exudate (the number of neutrophils usually exceeds 10x10 ³ cells / ml), which does not require special procedures and treatment, the resolution occurs as the pneumonia regresses.

The development of complicated parapneumonic effusion (also neutrophilic exudate) is associated with the penetration of infectious agents into the pleural cavity. Bacteria cause a change in the metabolism of glucose to the anaerobic pathway, with a decrease in glucose concentration and the development of pleural fluid acidosis, and as a result of leukocyte lysis the increase in LDH effusion activity is determined. Clearance of bacteria from the pleural cavity is carried out quickly enough, patients are prescribed antibacterial treatment, so a complicated parapneumonic effusion, as a rule, is sterile. Persistent inflammation causes the deposition of fibrin on the visceral and parietal pleura sheets and leads to the development of an adhesion process and the entrapment of the effusion.

Empyema is defined as the presence of pus in the pleural cavity. This stage of parapneumonic effusion is characterized by a large number of bacteria (detected with Gram staining) and leukocytes (more than 25x10 ³ / ml, their presence causes a macroscopic picture of purulent effusion). With the formation of purulent effusion, fibrin clots and membranes are usually formed on pleural sheets, and also effusion is tightened, in addition, in the later stages (2-3 weeks), the migration of fibroblasts into fibrin overlays is noted, this leads to the organization of the pleural cavity. With the development of empyema necessarily perform drainage of the pleural cavity and, often, surgical decortication of the pleura.

The occurrence of complicated pleural effusions and empyema is most often due to the presence of background diseases such as diabetes mellitus, alcoholism, COPD, bronchiectatic disease, rheumatoid arthritis. In men, these forms of pleurisy are diagnosed approximately twice as often.

The microbiology of parapneumonic effusions reflects the spectrum of causative factors of pneumonia. As studies have shown, in recent years there have been significant changes in the properties of microorganisms that cause parapneumonic pleurisy (this fact is associated with the use of antimicrobial agents for the treatment of pneumonia). Currently, the main cause of development of complicated parapneumonic effusions is penetration of the pleural cavity of Gram-positive (Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus) and Gram-negative (Escherichia coli, Haemophilus influenzae, Klebsiella spp., Pseudomonas spp.) Aerobic bacteria. Anaerobic microorganisms (usually together with aerobic bacteria) lead to the formation of 36-76% of all empyem, but approximately 15% of parapneumonic effusions occur solely as a result of anaerobic infections. Prevotella spp, Fusobacterium nucleatum, Streptococcus intermedius, Bacteroides spp are anaerobic microorganisms that most often lead to the formation of complicated parapneumonic effusions.

Pleural effusion in pulmonary embolism

A pleural effusion of a small volume is found in 40% of patients admitted to the hospital for PE. Among them, 80% of the effusions are exudates, 20% - transudates, as a rule, there is an admixture of blood in the pleural fluid (in 80% of cases). When a large number of erythrocytes is found in the pleural fluid (more than 100,000 cells / mm ³ ), it is necessary to exclude malignant neoplasm, lung infarction or trauma. A smaller number of red blood cells has no diagnostic significance. The exacerbations caused by PE have no specific traits. Therefore, the diagnosis is made on the basis of clinical data, which makes it possible to suspect PE with a high probability.

Tuberculous pleurisy

Acid-resistant sticks in smears are found only in 10-20% of patients with tuberculous pleurisy, and pleural fluid culture allows to determine mycobacterium tuberculosis only in 25-50% of cases. Performing histological examination and culture of the pleural biopsy improves the diagnosis of tuberculosis by up to 90%. In tuberculosis, in contrast to exudates of other etiology, an increase in the activity of adenosine deaminase occurs in the pleural fluid. However, an increase in this indicator is also recorded with empyema, rheumatoid pleuritis and malignant diseases, which leads to a decrease in the diagnostic value of adenosine deaminase analysis in countries with a low incidence of tuberculosis. Increases in adenosine deaminase activity do not occur in patients with HIV infection who have tuberculosis.

Pleural effusion in HIV infection

Pleural effusion is diagnosed in 7-27% of patients with HIV infection hospitalized in the Kaposi Sarcoma hospital, parapneumonic effusions and tuberculosis are the main causes of pleural effusion in these patients. A prospective study involved 58 people with HIV infection. All the subjects found radiographic signs of pleural effusion. As the study showed, one third of the patients were caused by Kaposi's sarcoma, 28% of patients had parapneumonic effusion, and 14% and 10%, respectively, of tuberculosis and pneumonia caused by Pneumocystis jiroveci. Lymphoma was diagnosed in 7% of patients who participated in the study.

Chilothorax and pseudochlorotorax

True chyloid effusion occurs as a result of rupture of the thoracic duct or its branches, which leads to the ingress of lymph into the pleural cavity. Approximately 50% of such cases in patients with malignant neoplasms (mainly lymphomas). The presence of trauma (especially in surgical interventions) also causes the formation of a true chyloid effusion (25% of cases). Sometimes the cause of this condition are such diseases as tuberculosis, sarcoidosis or amyloidosis.

Chilothorax should be distinguished from pseudochlorothorax, or "cholesterol pleurisy", which is formed as a result of the accumulation of cholesterol crystals in a long-term pleural effusion. In this case, as a rule, there is a significant thickening of the pleura and its fibrosis. The main causes of pseudochlorothorax are tuberculosis and rheumatoid arthritis. The diagnosis of chylothorax and pseudochlorothorax is established based on an analysis of the lipid content in the pleural fluid.

In rare cases, with empyema, a milk-colored effusion similar to chylothorax is observed. These states are distinguished by centrifugation. After it, with empyema of the pleura, a transparent supernatant is formed, and the cell mass settles. The liquid after centrifugation remains milky.

[18], [19], [20], [21], [22], [23], [24], [25], [26], [27]

Diagnosis of pleural effusion

Diagnostic studies are designed to document the presence of pleural fluid and determine its cause.

Chest X-ray is the first study to confirm the presence of pleural fluid. If there is a suspicion of pleural effusion, chest radiography should be performed in the lateral projection, in the vertical position of the patient. In this case, 75 ml of fluid is localized in the posterior costo-diaphragmatic corner. Large pleural effusions are visualized as blackouts of a portion of the thorax; effusions of more than 4 liters can cause a complete darkening and even a displacement of the mediastinum.

Localized (drained) effusions - the accumulation of fluid located between the pleural spikes or within the interstitial fissure. If the nature of the dimming is unclear, as well as whether the suspected effusion is coherent or free, radiographs of the chest organs in the lateral projection, in the supine position, CT of the thoracic organs or ultrasound examination should be performed. These studies are more sensitive than X-ray in the vertical position of the patient, and are able to detect liquids of less than 10 ml. The encapsulated liquid, especially in the horizontal or oblique interstitial fissure, may be mistaken for a solid formation of the lung (false tumor). This formation can change shape and size when the patient's position changes and the amount of pleural effusion.

CT is usually not performed, but it is important for evaluating the adjacent sections of the lung parenchyma for the presence of infiltrates or tumors, when the lung is darkened by effusion, and in differential diagnosis of fluid accumulation of fluid and solid formations.

Puncture of the pleural cavity should be performed in almost all patients, the volume of the first developed and unexplained etiology of pleural effusion in which is more than 10 mm in thickness on a side x-ray in a supine position or with ultrasound examination. Despite the common practice, chest radiography should not be repeated after this procedure, except for cases in which the patient develops symptoms that allow him to suspect pneumothorax (dyspnea or chest pain) or possible air entry into the pleural cavity during the procedure. Puncture of the pleural cavity and subsequent examination of pleural effusion is often not required for chronic pleural effusions that have a known cause and do not cause clinical manifestations.

Ultrasonography is useful for determining the location of the pleural fluid before puncture, when the blind pleurocentesis was unsuccessful.

Pleural fluid examination is performed to diagnose the cause of pleural effusion. It begins with a visual inspection, which allows you to differentiate hemorrhagic and chylous (or chylo-like) from other effusions; it is also possible to identify purulent effusions, indicating the presence of pleural empyema, and a viscous fluid, characteristic of some mesotheliomas. In all cases it is necessary to perform a study on the total protein content , lactate dehydrogenase, counting the total number of cells and their composition, microscopy after Gram stain and planting on aerobic and anaerobic nutrient media. Other studies ( glucose concentration , cytological, markers of tuberculosis in fluid (adenosine deaminase or interferon gamma), amylase, mycobacteria and microscopy after staining for the presence of fungi and isolation of their culture) are used in appropriate clinical situations.

Investigation of the chemical composition of the liquid allows differentiating the transudates from exudates; there are many criteria, none of which is universal. When using the Lite criteria, blood sampling to determine the concentrations of LDH and the total protein in its serum for comparison with similar parameters of the pleural fluid should be made as close as possible to the time of the pleurocentesis. The criteria of Light correctly identify almost all the exudates, but falsely define approximately 20% of the transudates as exudates. If the presence of a transudate is suspected (for example, with heart failure or liver cirrhosis) and none of the biochemical parameters exceeds more than 15% of the threshold values of the Light criteria, then the difference in the concentration of the total protein in blood serum and pleural fluid is investigated. If the difference is more than 3.1 g / dl, then, probably, it is a question of the transudate.

If the diagnosis remains unclear and after a pleural fluid study is performed, a spiral CT scan is performed, the task of which is to identify emboli in the pulmonary artery, pulmonary infiltrates or mediastinal lesion. Detection of the embolus in the pulmonary artery indicates the need for prolonged anticoagulant therapy; parenchymal infiltrate requires bronchoscopy, volumetric mediastinal formations - transthoracic aspiration biopsy or mediastinoscopy. However, to hold spiral CT it is necessary to hold your breath for more than 24 seconds, which not all patients are capable of. If helical CT is not informative, the best option for further examination is observation, except for the situation when a patient has a malignant neoplasm, a decrease in body weight, a constant increase in body temperature, or other changes that make one suspect a malignant process or tuberculosis; in the latter situation, it is possible to perform thoracoscopy. Puncture biopsy of the pleura can be performed if it is impossible to perform thoracoscopy. In case of non-informative thoracoscopy, in some cases thoracotomy should be performed. Most patients with exudative effusion should also have a tuberculin test with control.

[28], [29], [30], [31], [32]

How is pleural effusion treated?

The main disease is treated ; The actual effusion does not require treatment if it is asymptomatic, as many of them are resolved spontaneously, especially those that arise due to uncomplicated pneumonia, pulmonary embolism and surgical interventions. Pleuric pain is usually stopped by taking oral analgesics, only in some cases a short course of oral opioids is required.

Puncture of the pleural cavity with evacuation of exudate is sufficient treatment for many symptomatic effusions and can be performed repeatedly with repeated accumulation of fluid. Removing more than 1.5 liters of pleural fluid is simultaneously unacceptable, as this can lead to pulmonary edema due to the rapid expansion of the alveoli previously compressed by the fluid.

Chronic recurrent effusions, accompanied by clinical symptoms, can be treated by periodic pleural puncture or by the installation of permanent drainage of the pleural cavity. Exudations caused by pneumonia and malignant neoplasms may require additional special treatment.

Medication

Transudates usually do not require mechanical removal of fluid from the pleural cavity, except in cases of massive pleural effusions, which cause pronounced dyspnea. As a rule, the main method of therapy of transudates is treatment of the underlying disease, for example, improvement of myocardial contractility and correction of water metabolism in congestive heart failure. The appointment of diuretics and albumin solution has a fairly good effect in the treatment of patients with transudates against hypoproteinemia. Correction of severe hypoproteinemia should be carried out gradually to prevent a rapid increase in the volume of intravascular fluid. It is preferable to make long-term infusions of furosemide (while correcting the loss of potassium and magnesium), rather than injecting it bolus. In severe hypoproteinemic conditions, it is recommended to use spironolactone. A special problem is the management of patients with parapneumonic pleural effusions and pleural empyema.

The way to treat parapneumonic pleural effusion primarily depends on its stage and the risk of adverse outcome. In 2000, at the meeting of the American College of Chest Physicians, the ABC classification of parapneumonic pleural effusions was developed, taking into account the anatomical characteristics of pleural effusion (A), pleural fluid bacteriology (B) and pleural fluid biochemical analysis (C). Based on this classification in the group of parapneumonic effusions, four prognostic categories are identified that determine the indications for the establishment of a drainage tube (necessary for patients that make up groups III and IV at risk).

With uncomplicated parapneumonic pleural effusion, the patient is monitored and antimicrobial therapy is prescribed. To treat patients with community-acquired pneumonia, use second- or third-generation cephalosporins or inhibitor-protected penicillins.

If an anaerobic flora is suspected of contamination, a combination therapy with metronidazole or clindamycin is prescribed, inhibitor-protected penicillins or carbapenems. Antibiotics that penetrate well into the pleural cavity include penicillins, metronidazole, ceftriaxone, clindamycin, vancomycin. Aminoglycosides practically do not penetrate into the cavity of the pleura. There are no proofs of the effectiveness of direct instillations of antibacterial drugs into the pleural cavity.

Schemes of prescribing antibacterial drugs used for starting therapy of pleural effusions with negative culture found in the pleural fluid

Community-acquired infection	Cefuroxime in a dose of 1.5 g (3 times a day intravenously) in combination with 400 mg of metronidazole (3 times a day orally) or 500 mg of metronidazole (3 times a day intravenously)	Amoxicillin / clavulanate in a dose of 825/125 mg (3 times a day)
	Amoxicillin / clavulanate in a dose of 1.2 g (3 times a day intravenously) in combination with 400 mg of ciprofloxacin (2 times a day intravenously)	Amoxicillin in a dose of 1 g (3 times a day) in combination with 400 mg of metronidazole (3 times a day)
	Meropenem in a dose of 1 g (3 times a day intravenously) in combination with 400 mg of metronidazole (3 times a day inside) or with 500 mg of metronidazole (3 times a day intravenously)	Clindamycin in a dose of 300 mg (4 times a day)
Intrahospital infection	Piperacillin / tazobactam in a dose of 4.5 g (3 times a day intravenously)	Do not use
	Ceftazidime in a dose of 2 g (3 times a day intravenously)
	Meropenem in a dose of 1 g (3 times a day intravenously) is sometimes combined with 400 mg of metronidazole (3 times a day orally) or 500 mg of metronidazole (3 times a day intravenously)

With complicated pleural effusion, a drainage tube is installed or thoracocentesis is performed (as repeated punctures). With empyema, the pleural cavity drainage is considered to be the method of choice. The drainage tube, as a rule, is installed under the control of fluoroscopic examination, ultrasound or CT. In the presence of several voiced cavities, several drainage tubes are used. It is preferable to use large diameter tubes (24-36 P), especially if there is a viscous exudate in the pleural cavity. Usually, during the manipulation set negative pressure (10-20 cm H2O). With the correct location of the tube, a rapid evacuation of the fluid and the spreading of the lung take place. With a decrease in pleural discharge (up to 50 ml per day), the drainage tube is removed.

In the presence of an adhesion process in the pleural cavity or when there are detected cavities of adequate drainage of the pleural cavity, it is possible to achieve by introducing into it fibrinolytic agents that dissolve fibrin clots and membranes. The most commonly used streptokinase (at a dose of 250,000 units) or urokinase (at a dose of 100,000 units), the drugs are injected into 100 ml of saline and cover the drainage tube for 2-4 hours, then remove the pleural fluid. Depending on the clinical response, instillation of fibrinolytics is repeated for 3-14 days. Intrapureural administration of fibrinolytic agents does not cause systemic fibrinolysis. The effectiveness of the use of fibrotic drugs in the treatment of constricted pleural effusions is 70-90%.

Contraindications to the use of fibrinolytic drugs

• Absolute contraindications
  • Previous allergic reactions
  • Presence of bronchopleural fistula
  • Injury or surgery (within the previous two days)
• Relative contraindications
  • Large surgical interventions performed in the last two weeks
  • Hemorrhagic stroke in history
  • Head trauma or surgery (within the previous two weeks)
  • Violations of the coagulation system
  • Previous thrombolysis with streptokinase (contraindication only for streptokinase)
  • Previous streptococcal infections (contraindication only for streptokinase)

Thoracoscopy is an alternative to the fibrinolytic method of therapy of coagulated pleural effusions. The effectiveness of thoracoscopy when draining empyema of the pleura reaches 90%. In the absence of the effect of drainage of the pleural cavity, fibrinolytic therapy and thoracoscopy resort to surgical drainage - open thoracotomy and lung decortication.

Surgery

Surgical methods are highly effective (up to 95%), but their implementation is associated with a certain operational risk.

Parapneumonic effusion

In the presence of adverse prognostic factors (pH <7.20, glucose concentration <60 mg / dL, lactate dehydrogenase content> 1000 IU / l, detection of microorganisms after microscopy after Gram staining or in culture medium, pleural empyema) by draining the pleural cavity or puncturing it. If full drainage is not possible, intrapleural injections of fibrinolytic agents (for example, urokinase at a dose of 100,000 units per 100 ml of physiological saline) are used. In the absence of the effect of such treatment, a thoracoscopy is performed, the purpose of which is to destroy the adhesions and to provide drainage of the focus. In the absence of its effect, thoracotomy and decortication of the lung (with the removal of adhesions, clots or fibrous capsule surrounding the lung) is performed.

Pleural effusion in malignant tumors

If the dyspnea caused by malignant pleural effusion decreases after the pleurocentesis, but the liquid continues to accumulate, permanent drainage is established in the pleural cavity or pleurodesis; asymptomatic effusions and effusions resistant to the pleurocentesis, do not require additional treatment.

The installation of permanent drainage is the preferred method of treatment for outpatients, since this procedure can be performed on an outpatient basis, after which the pleural fluid is evacuated directly into vacuum vials. Shunting of pleural fluid in the abdominal cavity (pleuroperitoneal shunt) is used in patients with effusion caused by malignant neoplasms, in the absence of the effect of pleurodesis or the development of the lung carcinoma.

Pleurodez is produced by introducing a sclerosing agent into the pleural cavity in order to induce the fusion of visceral and parietal pleural sheets and obliteration of the pleural cavity. The most effective and commonly used sclerosing agents are talc, doxycycline and bleomycin, administered through the pleural drainage tube or during thoracoscopy. Pleurodez is contraindicated in the displacement of the mediastinum to the side of effusion and in the absence of pulmonary dilatation after the installation of pleural drainage.

What prognosis does pleural effusion have?

The prognosis of pleural effusions depends mainly on their nature. However, it can be assumed that the formation of pleural effusion worsens the prognosis of the underlying disease. Pleural effusion is one of the independent prognostic factors of community-acquired pneumonia that is part of some prognostic indices. Studies have shown that pleural effusion is an unfavorable prognostic sign, especially for patients with pneumonia caused by legionella, and for patients with HIV infection.