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Atelectasia: what it is and why it happens

Atelectasis is a lung disorder in which a part of the lungs collapses as a result of the loss of alveolar volume.

It is usually of idiopathic cause; that is, you do not know or there are so many that you can not determine what it is. Thoracic trauma, pneumonia, hormonal problems or respiratory insufficiency derived from other pathologies can cause atelectasis.

Physiological bases of respiratory function

Atelectasia: what it is and why it happens

First, the main function of the lungs is to supply oxygen to the blood and remove excess carbon dioxide produced in cellular respiration. This is achieved by inhaling oxygen-rich air and exhaling air rich in carbon dioxide. This air reaches the alveoli, tiny grape-shaped structures covered by a large number of tiny blood capillaries.

In them the gas exchange takes place. So that the alveoli can perform their function they must remain always open and full of air. This process is complicated during the exhalation, where the alveoli present a natural tendency to close and collapse.

But how do you avoid the collapse then? The key lies in the substance that covers them, such as the oil that is used to grease the hinges of a door, facilitating its function. The substance produced by type II pneumocytes that lines the surface of the pulmonary alveoli is known as pulmonary surfactant .

Surfactants, also known as surfactants, are molecules that decrease surface tension . And what is surface tension? The amount of energy needed in a liquid to increase its surface area per unit.

When thinking about the typical toy of the children with whom they create soap bubbles, in this case, the soap would work as a surfactant decreasing the surface tension of the bubbles. The smaller the surface tension, the bigger the size of the bubbles

If we tried to create bubbles only with water, we would be incapable because their surface tension is very high. In fact, it is so big that some insects take advantage of it to walk on

When there is a deficit of surfactant, some trauma occurs or breathing is hampered as a result of excessive secretions, there is a risk that part of the lungs will collapse causing atelectasis.

However, the human body itself has the necessary mechanisms to reduce the likelihood of this happening. Periodic deep breaths performed unconsciously or coughing to remove excess secretions from the airways are two of these mechanisms.

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Causes of atelectasis

Atelectasia: what it is and why it happens

The nature of this pathology is usually idiopathic. For example, a disorder in the endocrine system whereby hormone levels are altered. A decrease in the levels of hormones that promote the synthesis of surfactant by pneumocytes such as prolactin or thyroxine can lead to alveolar collapse.

On the other hand, the collapse can be triggered by the obstruction of one of the parts in which the lungs branch: the bronchi . This obstruction may be the result of inhaling a foreign body , such as a piece of food or a toy; or by the presence of a mucous plug or even a tumor.

Alternatively, the obstruction can be caused by something that compresses the bronchus from the outside , such as trauma, inflammation of a nearby lymph node, or, again, a tumor.

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In addition, other pathologies associated with the lungs as an increase in the fluid contained in the pleural space, a condition known as pleural effusion; or the entry of air in this same space, which is known as pneumothorax , can again lead to bronchial tamponade.

The diagnosis is usually made by a chest radiograph which allows to see if any bronchus is obstructed or if the alveolar volume is unusual. On the other hand, the treatment of this pathology consists of resolving the tamponade in case this is the cause or ensuring a deep breathing.

Atelectasia: what it is and why it happens