Symptoms and consequences
Depending on how an atelectasis develops and how large the affected part of the lung is, the development and the reappearance of an atelectasis can either go unnoticed or be associated with pain, coughing and severe breathing difficulties. Especially the development of a so-called pneumothorax is often painful. Since there is a lack of oxygen in the affected areas, the blood flow is reactively reduced by tightening the vessels (Euler-Liljestrand mechanism).
This is to ensure that the blood flowing through the lungs is really rich in oxygen afterwards. However, this constriction (vasoconstriction) also increases the resistance against which the right heart has to pump, which can lead to further problems, especially in cases of pronounced atelectasis or pre-existing heart failure. Furthermore, the lung parts with poor blood supply are more susceptible to infections and inflammations, e.g. pneumonia, and water deposits (edema) are more likely. If the blood in the lungs as a whole is no longer loaded with sufficient oxygen, this can lead to so-called cyanosis with blue discoloration of fingernails, lips and tongue. The clinical picture of a tension pneumothorax, in which the air accumulation around the lung increases with every breath through a valve mechanism, is life-threatening.
During the medical examination an atelectasis with a damping of the knocking sound presents itself, during listening (auscultation) a weaker breathing sound is noticeable. With the help of an X-ray, CT or ultrasound examination, atelectasis is also characterised above all by a decrease in volume of the affected area and an associated increase in density. In the case of a larger atelectasis, surrounding structures can shift towards it.
Recently, the MRI of the lung with helium has been added as a newer diagnostic procedure. An atelectasis is shown in the X-ray image as uniform shadows, which are oriented towards the boundaries of the lung lobes. The radiological findings show a reduction of the lung volume due to the airless areas of the atelectasis. Depending on the extent of the atelectasis, there is also an elevation of the diaphragm and a displacement of the lungs and trachea to the affected side.
Small atelectases usually disappear on their own or with the help of rearrangements and breathing exercises; intervention is particularly necessary for larger events. In the case of a compression atelectasis, the constricting element (air, blood, pus, water) is then removed with the aid of a draining tube (drainage). Ventilation with overpressure is also conceivable in order to allow the compressed lung sections to unfold again. Symptomatically, oxygen can be added to the breathed air. Above all, however, with atelectasis it is always important to clarify the cause, as atelectasis can be a sign of a serious illness.