Reasons for the development of pathology
There are many causes for the development of pulmonary fibrosis. These include:
- Diseases of the respiratory system (COPD, pneumonia, tuberculosis).
- Systemic connective tissue diseases (scleroderma, SLE, rheumatoid arthritis).
- Taking a number of medications (cytostatics, antiarrhythmic drugs).
- Vasculitis of various origins.
- Harmful production factors (asbestos, silicates, etc.).
Idiopathic pulmonary fibrosis is also isolated when the cause of the pathological process cannot be determined.
Clinical manifestations
The severity of symptoms directly depends on the extent of damage to the lung tissue, as well as on how quickly the collapse of the alveoli develops. If this process occurs quickly and affects an entire lobe or the entire lung, acute respiratory failure develops, which can soon lead to the death of the patient. Symptoms in this case become:
- sudden onset of severe shortness of breath;
- dry cough;
- intense pain in the chest on the affected side;
- severe arterial hypotension;
- cardiopalmus;
- cyanosis (blue discoloration) of the skin.
Atelectasis of small size may initially occur completely without any symptoms, but gradually the patient will experience subtle shortness of breath, the intensity of which will increase over time, in the absence of treatment. In the future, in an area with reduced airiness, atelectatic pneumonia will occur - pneumonia.
In the case of an increase in body temperature, the appearance of a productive cough, general weakness and increasing signs of intoxication, the onset of abscess pneumonia should be suspected.
Signs and symptoms
Signs and symptoms may be absent or include:
- cough, but not noticeable;
- chest pain (not common);
- difficulty breathing (fast and shallow);
- low oxygen saturation;
- pleural effusion (transudative type);
- cyanosis (late sign);
- increased heart rate.
It is a common misconception and pure speculation that atelectasis causes fever. A study of 100 postoperative patients followed by serial chest x-rays and temperature measurements showed that the incidence of fever decreased as the incidence of atelectasis increased. A recent review article summarizing the available published data on the association between atelectasis and postoperative fever concluded that there is no clinical evidence to support this suggestion.
What is atelectasis?
Atelectasis is the collapse or collapse of the lung, resulting in decreased or absent gas exchange. It is usually a unilateral disease affecting part or all of one lung. Atelectasis is a condition in which the alveoli are deflated to little or no volume, as opposed to pulmonary consolidation, in which they are filled with fluid. It is often called pulmonary collapse , although the term can also refer to pneumothorax.
The condition is very often detected on chest x-rays and other radiological studies and can be caused by a variety of common conditions and diseases. Although atelectasis is often described as collapse of lung tissue, it is not synonymous with pneumothorax, which is a more specific condition characterized by atelectasis. Acute atelectasis can occur as a postoperative complication or as a result of surfactant deficiency. In premature babies this leads to respiratory distress syndrome.
The term uses a combination of the forms atel— + ectasis from the Greek: ἀτελής, “incomplete” + ἔκτασις, “stretching.”
Diagnostics
Clinically significant atelectasis is usually visible on a chest radiograph; results may include lung opacities and/or loss of lung volume. Postoperative atelectasis will be bibasal. If the cause of atelectasis is not clinically obvious, a chest CT scan or bronchoscopy may be needed. Direct signs of atelectasis include displacement of interlobar fissures and mobile structures within the chest, excessive inflation of the unaffected ipsilateral lobe or contralateral lung, and opacification of the collapsed lobe.
Classification
Atelectasis can be an acute or chronic disease. In acute atelectasis, the lung has recently collapsed and is primarily characterized by the absence of air. In chronic atelectasis, the affected area is often characterized by a complex mixture of lack of air, infection, dilatation of the bronchi (bronchiectasis), destruction and scarring (pulmonary fibrosis).
Absorption (resorbable) atelectasis.
The Earth's atmosphere mainly consists of 78 vol. % nitrogen and 21 vol. % oxygen (+ 1 vol.% argon and traces of other gases). Since oxygen is exchanged at the alveolar capillary membrane, nitrogen is the main component of the inflated state of the alveoli. If a large volume of nitrogen in the lungs is replaced by oxygen, the oxygen can subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorptive atelectasis.
— Compression (relaxing) atelectasis.
The condition is usually associated with the accumulation of blood, fluid or air in the pleural cavity, causing the lung to mechanically collapse. This is a common finding in pleural effusion caused by congestive heart failure (CHF). Leakage of air into the pleural cavity (pneumothorax) also leads to compression atelectasis.
— Cicatricial (contraction) atelectasis.
It occurs when local or generalized fibrotic changes in the lungs or pleura prevent expansion and increase elastic recoil during exhalation. Causes include granulomatous disease, necrotizing pneumonia, and radiation fibrosis.
Chronic atelectasis.
Chronic atelectasis can take one of two forms - middle lobe syndrome or rounded atelectasis.
- Right middle lobe syndrome.
In right middle lobe syndrome, the middle lobe of the right lung is compressed, usually due to pressure on the bronchus from enlarged lymph nodes and sometimes from a tumor. A blocked, compressed lung can develop pneumonia, which does not go away completely and leads to chronic inflammation, scarring, and bronchiectasis.
- Spotted atelectasis.
Occurs due to a lack of surfactant, as occurs in neonatal hyaline membrane disease or acute (adult) respiratory distress syndrome (ARDS).
- Rounded atelectasis.
In rounded atelectasis (folded lung syndrome or Blesovsky syndrome), the outer part of the lung slowly collapses as a result of scarring and compression of the membrane layers covering the lungs (pleura), which manifests itself as thickening of the visceral pleura and entrapment of lung tissue. This gives a rounded appearance on an X-ray that doctors may mistake for a tumor. Round atelectasis is usually a complication of asbestosis (a disease of the pleura associated with asbestos exposure), but it can also result from other types of chronic scarring and thickening of the pleura.
Causes and risk factors
The most common cause is postoperative atelectasis, characterized by splinting, that is, restriction of breathing after abdominal surgery.
Another common cause is pulmonary tuberculosis. Smokers and older people are also at increased risk. Outside of this context, atelectasis implies some obstruction of a bronchiole or bronchus, which may be internal to the airway (foreign body, mucus plug), from a wall (tumor, usually squamous cell carcinoma), or compressed externally (tumor, lymph node, tubercle). Another reason is poor surfactant distribution during inspiration, causing surface tension that tends to collapse the smaller alveoli. Atelectasis can also occur during sanitation of the respiratory tract, since air is removed from the lungs along with sputum. There are several types of atelectasis depending on the underlying mechanisms or extent of alveolar collapse; resorption (obstructive), compression, microatelectasis and contraction atelectasis. Relaxing atelectasis (also known as passive atelectasis) is when pleural effusion or pneumothorax disrupts the contact between the parietal and visceral pleura.
Risk factors associated with an increased likelihood of developing the disorder include:
- type of surgery (thoracic, cardiopulmonary surgery);
- use of muscle relaxants;
- obesity;
- high oxygen levels.
Factors not associated with the development of atelectasis include:
- age;
- the presence of chronic obstructive pulmonary disease (COPD) or asthma;
- type of anesthetic.
