Pleural effusion

A pleural effusion is a condition in which a large amount of fluid accumulates in the pleural cavity of the lungs.

The space between the thoracic wall and lungs where the fluid collects is called the pleural cavity or pleural space.

This gap space is bounded by two pleures:

  • The pleura visceralis (pleura) is the inner membrane.
  • The pleura parietalis (pleura) is the outer layer and is in contact with the rib cage.

Between the lungs and the thoracic wall there is a thin layer of fluid of about 10-15 ml. This fluid is important because it acts as a lubricant between the thorax and lungs during breathing, thus preventing friction.

It is called pleural effusion when the amount of fluid in the pleural cavity exceeds 200-300 ml.

The effusion can:

  • occur unilaterally (only left or right), for example, with embolism or cirrhosis of the liver;
  • occur bilaterally and be caused by heart failure.

It is called chambered when it shifts depending on the position of the patient.
In this case, it is referred to as:

  • Basal refers to when it is located at the base of the lungs
  • and apical, if it is located at the tip of the lung (upper area).

It is called organized pleural effusion when the fluid changes and becomes fibrous tissue. In this case, it can hinder breathing.


Origin of fluid in the pleural cavity

Pleures are semi-permeable membranes and consist of:

  • single-layered squamous epithelium,
  • a connective tissue layer with elastin and collagen.

The pleural fluid is subject to constant exchange.
The amount of liquid is given by the Starling equation:

  • There are two rooms separated by membranes; the room with the higher hydrostatic pressure (on the walls of the container) pushes the liquid to the room that has the lower hydrostatic pressure.
  • The room with a higher oncotic pressure (i.e. with a higher protein concentration) tends to attract the fluid from the other room.

Causes of pleural effusion

There are two types of pleural effusion:

    • blood, defined as hemorrhagic exudate;
    • lymphatic fluid, defined as chylothorax;
    • Pus, term empyema.Exudate, a turbid or dark liquid that may also contain:
  • Transudate, an aqueous or transparent, bright liquid.

The main differences between transudates and exudates are:

Total protein levels:

  1. Exudate with a protein content > 30 g/l
  2. Transudate with a protein content < 30 g/l

The ratio of proteins in the pleural fluid to proteins in plasma:

  • > 0.5 for exudate
  • < 0.5 for transudate

Ratio of LDH (L-lactate dehydrogenase) in pleural fluid to LDH in plasma:

  • Exudate has a ratio of > 0.6
  • Transudate has a ratio of < 0.6

The causes depend on the type of effusion.

Transudative pleural effusion

Transudative pleural effusion is caused by the entry of fluid into the pleural space, due to altered blood pressure in the pleural capillaries.
In a transudative pleural effusion, the capillaries are intact.

The effusion can have various reasons, but the most common cause is weakness of the left ventricle of the heart.

Most common causes of transudate

  1. Heart failure and heart failure (in this case, may appear together with pleural effusion)
  2. Cirrhosis with accumulation of fluid in the abdomen (ascites)
  3. Hypoalbuminaemia (low levels of albumin in the blood)
  4. Peritoneal

Less common causes

  1. Hypothyroidism
  2. Nephrotic syndrome
  3. Mitral stenosis
  4. Pulmonary embolism (in 80% of cases it is exudates, in the remaining 20% transudates)

Rare causes

  1. Narrowing of the superior vena cava (usually due to a tumor or lung metastases))
  2. Pericarditis
  3. Ovarian hyperstimulation syndrome
  4. Meigs syndrome (benign tumor on the ovaries, ascites and pleural effusion)

Exudative pleural effusion

Exudative pleural effusion is caused by fluid leakage from the blood vessels that have suffered lesions due to trauma or inflammation.
In a tumor, there is a change in lymphatic drainage.
The main cause of discharge is lung disease.
The exudate is cloudy.

Common causes of exudate

    1. Bacterial and viral pneumonia – About half of hospital patients with bacterial pneumonia develop parapneumonic pleural effusion (during pneumonia).
      Empyema (accumulation of pus) and parapneumonic pleural effusion are mainly detected in infants and children.
    2. Pulmonary embolism
    3. Tumor – usually lung cancer in men and mammary gland cancer (breast cancer) in women. Neoplasia is usually a unilateral pleural effusion.
  1. Trauma: abdominal surgery and after heart surgery (for example, about half of patients who had aortocoronary bypass surgery).

Less common causes

  1. Pulmonary infarction
  2. Autoimmune diseases, especially rheumatoid arthritis and lupus
  3. Asbestos exposure and mesothelioma
  4. Kidney disease (uremia)
  5. Pancreatitis
  6. Complication of myocardial infarction (Dressler syndrome)
  7. Infections of the lungs, for example, tuberculosis
  8. Subphrenic abscess (between diaphragm and liver)

Rare causes

  1. Yellow nail syndrome, characterized by yellow nails, lymphedema, pleural effusion and bronchiectasis
  2. Drug side effects (for example with methotrexate, methysergide, amiodarone, nitrofurantoin and phenytoin)
  3. Viral infection (for example, herpes zoster, morbillivirus, etc.)
  4. Fungal infection

Frequency of pleural effusions

In the United States, about 1.5 million cases are recorded annually.

Symptoms of pleural effusion

Possible signs of pleural effusion include:

Diagnosis of pleural effusion

Physical examination

Inspection – The doctor must clarify the following questions:

  1. Has any weight loss been noticed that could indicate neoplastic effusion?
  2. Do the fingers have a nicotine-like coloration? They can indicate diseases of the respiratory system.
  3. Are so-called Hippocrates fingers noticeable? They can be an indication of lung infections, heart disease and neoplasms of the lungs.
  4. Are there rheumatic changes?
  5. Is the patient short of breath, does he have breathing problems?
  6. Are the lymph nodes enlarged?
  7. Does the patient have difficulty moving? If the effusion is one-sided and significant (at least 1 liter), mobility on this side of the thoracic is limited.

Palpation – The doctor must pay attention to the following aspects:

  • The breast expands less on the side of the effusion.
  • A deviation of the trachea is detectable.
    If the lungs have not collapsed, the trachea is deflected to the affected side.
  • The voice fremitus may be reduced.

Percussion – The effusion produces a muffled sound during percussion.

Auscultation – The doctor places the stethoscope on the chest and listens to the sounds coming from the lungs:

  • The vesicular breathing sound is attenuated or completely absent during effusion.
  • In a pleural effusion, the voice resonance is lost to the upper area. This phenomenon is called egophony and is reminiscent of the moaning of a goat.

Imaging studies

The first step in diagnosis is a simple chest X-ray; This shows:

  • a very wide opacity (white spot); with a left-sided effusion, the heart is covered, with a right-sided effusion, the lower right lobe is covered;
  • the outer edge of the white spot is higher than the middle, this figure is called the pleural meniscus
    The reason for this is the capillary effect, that is, when a narrow tube is inserted into a liquid, the liquid in the tube rises above the level of the outer liquid.

Ultrasound and CT

  • To confirm the presence of excess fluid, an ultrasound, a CT, or both are performed.
  • With ultrasound, the size of the effusion can be determined.
  • With exposure to asbestos, calcifications and pleural plaques can be detected.

In the second step, a sample of the pleural fluid is analyzed.

Thoracocentesis and examination of pleural fluid

  • The extraction of the fluid for analysis is called therapeutic thoracentesis.
  • In the area of effusion, local anesthesia is performed.
  • With the help of a needle, some liquid is taken.
  • The amount withdrawn can range from 30 ml to 2 liters.
  • In some cases, the fluid is removed by inserting intercostal pleural drainage.
    If the patient has cancer, the fluid is removed by inserting a chest drainage.
  • This process may take longer than a day.

Evaluation of the pleural fluid

Analysis of pleural fluid

If the liquid is cloudy, the possible causes are:

A bloody effusion can be caused by:

  • a tumour,
  • a trauma.

A milk-like exudate may be due to:

  • a ruptured lymphatic vessel,
  • a neoplasia (lymphoma).

If the liquid contains pus, the causes may be:

  • a bacterial infection,
  • an abscess.

If the pH of the liquid is less than 6.8, the patient may suffer:

  • Empyema
  • Rupture of the esophagus.

Differential diagnosis

The doctor must exclude:

  • Q fever
  • Diaphragmatic injuries or hernias
  • Injury to the esophagus
  • Thickening or fibrosis of the pleura
  • Pulmonary atelectasis (lung collapse)

Malignant pleural effusion

This is a respiratory complication that can occur in cancer patients.

Malignant pleural effusions are caused by pleural metastases. This form of pleural effusion occurs in patients with malignant tumors in an advanced stage.
Tumors that cause this complication include:

How to treat? Therapy for pleural effusion

If the effusion is caused by tuberculosis or other infection, the doctor prescribes:

Corticosteroids and antibiotics can also be taken during pregnancy, provided the doctor prescribes them.
If cancer is the cause, it may be necessary to:

If the effusion is due to heart failure, the doctor prescribes diuretics.

Pleural puncture. A large amount of fluid in the pleural cavity (massive effusion) must be drained to relieve symptoms.
This procedure is called pleural puncture (thoracocentesis). A thin plastic tube (catheter) is inserted:

  • into the thoracic wall,
  • into the pleural cavity.

The accumulated liquid is sucked off with a syringe connected to the pipe.

Surgical intervention for pleural effusion

If the disease recurs (which usually happens with a malignant tumor), the doctor may recommend pleurodesis (adhesion of the two pleural sheets).

  • In pleurodesis, the fluid is first drained from the breast.
  • Then a special chemical substance (sterile talc or bleomycin) is introduced into the pleural cavity.
  • The chemical product causes irritation of the pleural sheets, causing them to stick.
  • Thus, the gap is sealed and no liquid can collect in between.

Another treatment option for pleural effusion caused by malignant mesothelioma is pleurectomy, the surgical removal of the parietal pleura.

There are several procedures for removing the pleura:

  • Video-assisted thoracoscopy (VATS): A minimally invasive procedure in which the surgeon makes three small incisions through which the instruments are inserted.
  • Thoracotomy: The surgeon opens the thorax through an intercostal incision to gain access to the diseased lung, removes the lungs and removes the pleura.

A shunt (tube) is inserted into the thorax, through which the pleural fluid can drain into the abdominal cavity.

Is pleural effusion fatal or recurrent? Prognosis

The duration of effusion depends on the underlying disease.
If the patient is treated in a timely manner, the risk of complications is lower.
The effusion may recur, especially if the patient has lung cancer. In this case, the doctor may recommend pleurodesis.
The effusion is dangerous but not contagious, although some infections responsible for it can be transmitted to another person.

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