What Are The Three Types Of Atelectasis?
Atelectasis refers to the full or partial collapse of a lung or a part of it. The term ‘Atelectasis’ is derived from two Greek words, i.e. ‘ateles’ and ‘ektasis’, which mean ‘incomplete expansion’. It is a common respiratory problem especially in postoperative patients who have undergone thoracic or abdominal surgeries.
What Are The Three Types Of Atelectasis?
Atelectasis is characterized not only by the collapse of a lung but also the failure of alveoli, which are tiny air spaces within the organ and low oxygen volume in the lungs. The condition can be categorized into three major groups which basically are related to the pathogenesis of the different types. They include; obstructive atelectasis, non-obstructive atelectasis, and adhesive atelectasis.
Obstructive (Absorption) Atelectasis
As the name suggests, this type of atelectasis is caused by blockage (obstruction) of the bronchial passageways by inhaled foreign particles. This leads to trapped air in the alveoli, which is slowly absorbed into the bloodstream. It also inhibits the proper circulation of air into the lungs, thus depriving the air sacs and lungs of oxygen altogether. Obstructive atelectasis can also occur as a complication of surgery (of the chest or abdomen), i.e. postoperative atelectasis, under anesthesia. This is because the anesthesia triggers an increase of bronchial secretions and also prompts shallow breathing. Other obstructions which can lead to this atelectasis include; malignancy and mucus plug.
Non-obstructive atelectasis can be caused by either injury to the chest, pleural effusion, lung scarring, lung infections and tumors close to the lungs. This type of atelectasis can further be grouped into relaxation (passive) atelectasis, compression atelectasis, replacement atelectasis, and cicatrization (contraction) atelectasis. Passive atelectasis is as a result of the loss of contact between the parietal and visceral tissue. This could be due to pleural effusions or pneumothorax. On the other hand, compression atelectasis is caused by pressure forcefully squeezing against the lungs pushing air out of the alveoli. It could be as a result of the chest wall or pleural masses or pleural fluid pressing against the lungs. Replacement atelectasis is related to the replacement of all of the alveoli in the lobe of a lung by a tumor. Cicatrization atelectasis is associated with parenchymal scarring, which leads to contraction of the lung. Chronic tuberculosis and fungal infections are major causes of contraction atelectasis.
This is prominent in premature babies, who are unable to breathe spontaneously as some of their air sacs do not inflate as expected. The reason behind this type of atelectasis is the lack of the surfactant in the alveoli, meaning they’re constantly collapsed. The surfactant is a surface tension material that keeps the alveoli open. The infants are born without this surface and treatment involves a replacement therapy with the surfactant. Infants with this condition are said to suffer from respiratory distress syndrome. Older adults can also develop adhesive atelectasis as their surfactant wears out over time. This could be as a result of prolonged shallow breathing, cardiac bypass surgery, smoke inhalation or hyaline membrane disease.
Symptoms of Atelectasis
In general, some of the potential symptoms you’re likely to experience include;
- Difficulty breathing.
- Coughing and wheezing.
- Rapid shallow breathing.
- Fever, in case a large area of the lung is affected.
- Pain around the affected side of the lung.
- Cyanosis, which is a bluish discoloration on the skin on the affected side of the lung.
Types of atelectasis are associated with the causative factors of the condition. The most common factors that can cause atelectasis include; internal obstruction of airways, external compression of airways, compression of lung parenchyma, suppression of respiration and also thoracic and abdominal surgeries. Understanding what type of atelectasis is crucial as it helps identify probable complications as well as best the approach for treatment. Obstruction atelectasis is the most common type whereas the adhesive atelectasis is the least common. With time and the right treatment, atelectasis gets better, however, if left untreated, it can cause serious complications. For example; pneumonia, pleural effusions, bronchiectasis, and respiratory failure.