What are the pleurae?
Before we start talking about pleural effusion, it is necessary to clarify what pleurae are. They are a kind of sac that surrounds each of the two lungs. They consist of two sheets: a visceral one which is tightly attached to the lung, and a parietal one which is located outside the visceral sheet. Between the two sheets, there is a very thin liquid veil, which has the purpose of ensuring that the lungs can expand with each breath without creating friction inside the chest; moreover, it ensures that the two sheets remain adherent to each other (it is the same effect, which we can all see, that is created when a drop of water is placed between two slides placed one on top of the other: the two slides slide easily l 'one on the other without more friction, but to detach them it takes much more strength).
The liquid is continuously renewed: in fact, about 15ml of it are produced every day by the mesothelial cells (i.e. the very thin cells that make up the mesothelial tissue, of which the sheets are composed), while as many are absorbed by the lymphatic system. This turnover it is very important and follows the law that no liquid in our organism must remain unchanged for a long time: this is to prevent it from becoming a place of easy replication for bacteria.
What is pleural effusion?
By effusion we mean the accumulation of liquid, of various nature and entity, inside a body cavity; in this case it is the pleural cavity, with consequent detachment of the sheets of which it consists.
The accumulated liquid can be of different nature:
- Oozed, or accumulation of liquid with low protein concentration. Often expression of pathologies affecting organs other than the pleura (liver, kidney, intestine, heart ...)
- Exudate, or accumulation of inflammatory fluid, with a high protein concentration. It is the expression of an inflammation that also affects (or only) the pleura.
- Lymphatic (Chylothorax)
- Hematic (Hemothorax)
Causes of pleural effusion
Let's now try to summarize the causes of each of these types of payments:
- Heart failure (responsible for 30-40% of pleural effusions): the heart in this situation struggles to pump blood, and does so with less energy, therefore it will move along the circulatory tree at low speed. This causes it to gradually accumulate at the level of the capillaries, also due to the fact that the venous outflow also occurs at a reduced speed: therefore, the increase in hydrostatic pressure at the level of the capillaries causes the passage of part of the component. fluid from blood vessels to the extracellular space, including the pleural cavity.
- Decrease in the amount of fluid removed by the lymphatic system: this can happen when the lymphatic vessels are compressed (for example by a tumor), or when the lymph nodes are "clogged": it can happen during infectious diseases or in the case of lymphoma .
- Slowed venous outflow: in addition to heart failure, it can appear in case of chronic constrictive pericarditis, Restrictive cardiomyopathy, pulmonary hypertension with decompensation of the right ventricle, compression of the thoracic veins (always, for example, due to a tumor of a nearby structure ), sclerosis of the vessels following radiotherapy.
- Decrease in oncotic blood pressure, or decrease in blood proteins, which have the function of retaining the liquid component inside the vessels, as if they were magnets capable of attracting water instead of iron. This occurs mainly in the case of hepatic insufficiency (for example, cirrhosis) and renal insufficiency (nephrotic syndrome), much more rarely in the course of intestinal diseases (insufficient protein absorption, for example in the course of inflammatory bowel diseases or pancreatitis) or malnutrition ( insufficient protein intake).
- Pulmonary embolism, or occlusion of one or more pulmonary vessels by a thrombus, almost always of deep venous origin. However, sometimes massive embolism affects large caliber vessels, resulting in a massive blockage of the blood supply, with pulmonary infarction and therefore inflammation, with accumulation of exudate rather than transudate.
- Pleurisy, which is acute inflammation of the pleurae, often following infection.
- Para-pneumonic form of Pleurisy, i.e. inflammation that starts at the level of the lung parenchyma (Pneumonia, Bronchopneumonia) and then extends to the pleura (Pleuropneumonia, which can arise both during the pneumonic episode and following its resolution).
- Malignant tumors, mostly metastatic of mammary origin (50%); Primary tumors of the pleura (mesotheliomas) are rare, although endemic (ie frequent in a limited territory) in areas highly polluted by asbestos.
- In case of massive blockage of the lymphatic outflow, with an increase in pressure such as to cause the rupture of the lymphatic vessels and extravasation of the lymph into the pleural space;
- Direct rupture of a lymphatic vessel during surgery or invasive interventions
- Filariasis or Tuberculosis
- Direct trauma, for example from a knife, bruises, fractures.
- Following surgery or invasive maneuvers, such as an incorrect thoracentesis
Types of pleural effusion
- Payment Unilateral: effusion occurs only at the level of one of the two pleurae, therefore either only on the right or only on the left. When will this circumstance occur? When the payment is due to a cause, among those listed above, which is not expressed at a systemic level, therefore widespread, but rather in a localized way. So, for example, in case of unilateral pleurisy, unilateral pulmonary embolism, unilateral tumor, hemorrhage. As you can guess, these are all causes that can affect only one of the two lungs (but if you are unlucky enough, nothing prevents both of them from being affected, but this rarely happens).
- Payment Bilateral: it is exactly the opposite of the above; both pleurae are affected, and this typically occurs in those conditions in which the effusion is a consequence of alterations that originate in other organs and which are expressed at the systemic level: therefore heart failure, liver failure, nephrotic syndrome, intestinal or pancreatic diseases , reduced venous outflow, etc.
- Payment Relapsing: the effusion recurs after a thoracentesis. For example in the case of mesothelioma or other malignant tumors.
- Payment a Shirt: As the name suggests, it is an effusion that envelops the lung over its entire surface, just like a shirt envelops the entire chest. The large surface is "compensated" by the fact that almost always the quantity of liquid is reduced (Pleural flap, i.e. an extensive but subtle collection), often to the point of being asymptomatic.
- Transudatory effusion
- Exudative effusion
- Blood effusion (Hemothorax)
- Fat effusion (Chylothorax)
Pleural effusion symptoms
- Dyspnea, or a feeling of wheezing or "hunger for air": it is due to the fact that the lung is unable to expand properly, being partially or totally compressed by the liquid.
- Pain, not always present, but which takes on typical characteristics in the course of pleurisy (easily recognizable by the doctor).
- Symptoms of the concomitant pathology (heart failure, cirrhosis ...)
- Very rarely, localized increase in the size of the chest (a kind of blockage is created)
Diagnosis of pleural effusion
- Chest X-ray (X-ray), which shows collections of 200-300ml, therefore it does not allow for early diagnosis. The payout is visible as a matting at the periphery of the lung, often defined as pleuro-parenchymal opacification, initially arranged at the level of the bases according to gravity (NB: usually the lungs are completely black on radiography, or radiolucent, as they are mostly made of air). It is very important to distinguish the opaque from thethickening pleural: the latter is a not infrequent radiographic finding, very often it is the result of contact with a pathological agent (in recent decades this agent was almost always the beating responsible for tuberculosis) which occurred in the past, therefore with null actual meaning. In some cases, however, it is the first radiological sign of a fearful neoplasm, the mesothelioma pleural, especially frequent in people who have come into contact with asbestos fibers (asbestos).
- Ultrasound, the most sensitive method and absolutely free of side effects, which allows a diagnosis early
- CT, as sensitive as ultrasound, with the further advantage of identifying possible secondary causes (infectious foci, thickenings, neoplastic masses…)
- Thoracentesis, which is not used to diagnose effusion, but rather to identify it the nature and the cause. It consists in taking liquid in order to analyze it. It also has therapeutic value, relieving dyspnea as the obstruction of lung expansion is removed.
- Biopsy, which allows the microscopic study of the pleural tissue, in order to identify specific causes. It is done by needle, or in progress Thoracoscopy, another useful diagnostic technique that allows the exploration of the pleural cavity through the insertion of a very small camera between the two sheets, through a small incision on the chest.
- Thoracotomy, which is performed as the last choice if an etiological diagnosis has not been reached with the methods mentioned above, or the cause of the effusion has not been found. It is performed under general anesthesia and allows the removal of large quantities of tissue.
Pleural effusion therapy
What is the treatment of pleural effusion? Are there effective treatments?
- Thoracentesis, which is almost always a palliative type of therapy, as the liquid is removed but not the cause, and therefore without further precautions the effusion is destined to recur.
- Diuretics: these are drugs that act in the kidney to inhibit the reabsorption of water, so as to eliminate it in greater quantities in the urine. In this way the blood volume decreases, and therefore the pressure at the capillary level.
- Treatment of the basic pathology: if, for example, the genesis of the effusion was Para-pneumonia, treating the pneumonia would resolve the situation and heal the patient.
- The underlying disease is not always treatable in the short term: if the genesis is for example neoplastic (mammary, ovarian metastases or primary lung or pleural tumors) it is appropriate to consider the P.chemical or talc leurodesis, that is to make the visceral and parietal leaflet adhere by means of irritating substances (Talc), which causing inflammation and fibrosis create adhesions between the pleural sheets, in order to hinder the collection of the effusion.
- Thoracoscopy, which allows cleaning of a limited portion of the pleural cavity.
- Thoracotomy, which as mentioned is a real one surgery, carried out under general anesthesia. In addition to the removal of large quantities of tissue, it allows the exposure of the pleural cavity, with the possibility of completely cleaning its contents and in cases of pathological adhesions, their decortication, with liberation of the lung.