The word atelectasis pertains to lung condition in which one or more area of lung is partially or completely collapsed. The tiny air sacs (alveoli) do not inflate properly in the affected part of the lung. Atelectasis often develops as side effect of general anesthesia after abdominal and chest surgery.
There are many other risk factors contributing atelectasis such as accumulation of fluid in lung, chest injury etc. Subsegmental atelectasis is a type of atelactesis where the lung volume is decreased as a result of obstruction in the subsegmental bronchus or a small bronchus.The proportion of collapse is very small and therefore there are hardly any symptoms experienced by the patient.
It is often noticed as few centimeter line at the base of lung just above the diaphragm on chest X-ray. The condition resolves on its own with chest exercise in majority of cases. Medications may be necessary in few cases where the symptoms produce discomfort.
What Are The Causes Of Subsegmental Atelectasis?
Atelectasis occurs due to obstruction in bronchus or the air passage. It can also develop due to pressure from outside the lungs which is non obstructive form.Several factors can cause atelectasis.
- General anesthesia: Acute form of subsegmental atelectasis may develop after general anesthesia. It occurs after the surgery is over. Mucus secretions may get accumulated in the tiny bronchi just near the air sacs. The obstruction prevents air sacs to re inflate which results in collapse of the alveoli. Aside from mucus secretions, blood clots in the bronchi may also impede the free air flow.
- Foreign body: Subsegmental atelectasis often occurs due to presence of tiny foreign body in the bronchus. It is more common in children where small edibles like grains and peanuts may get lodged in bronchus while ingesting.
- Narrow air passage: Chronic lung diseases such as bronchiactesis, tuberculosis of lungs can cause scaring of the lung tissue leading to atelectasis.
- Pleural effusion: Subsegmental atelectasis in pleural effusion occurs due to pressure from the fluid buildup in the pleura, the lining surrounding the lungs.
- Chest injury: Subsegmental atelectasis can occur after severe injury on chest. A severe blow on chest after car accident can compress the lungs leading to deflation of alveoli.
- Malignant and non malignant growths: Growth in lungs can compress the bronchi, which may result in restriction of airflow in the air sacs.
- Infection: Pneumonia is a lung disease caused by bacteria or viruses. It leads to collapse of lung tissue. Mild form of pneumonia can cause subsegmental atelectasis.
- Bed ridden patients: Subsegmental atelectasis occurs in patients who are bed ridden for a prolonged period of time. The secretions do not drain out as they should which causes obstruction in the air passage.
- Smoking, obesity, cystic fibrosis are few other triggers responsible for subsegmental atelectasis.
Symptoms Of Subsegmental Atelectasis
Subsegmental atelectasis is usually mild and does not produce symptoms that may cause discomfort for the patient. However, in few cases it may cause symptoms such as cough, breathing difficulty, and shortness of breath. The cough is non productive and hacking. Very small amount of mucus is coughed up.
Occasionally there is fever, but more prominently if there is an infection such as pneumonia or tuberculosis. Sometimes patient may experience shortness of breath while walking, however, in subsegmental atelectasis it is less common as very minimal area is involved.
Treatment For Subsegmental Atelectasis
Subsegmental atelectasis does not produce prominent symptoms and therefore it is confused with many other pulmonary conditions. Physical examination, chest X-ray, lung scan, and oximetry tests help in proper diagnosis.
In majority of cases the condition does not require any treatment, as healing occurs naturally within few days. As small area of lung is affected, lung function does not suffer and the other healthy lung tissue takes over the function. However, in certain cases treatment may be necessary which include following.
- Chest physiotherapy: Deep breathing exercise helps in draining cough and secretion that has accumulated. It also helps in re inflating the air sacs.
- Postural drainage plays an important role in removing plugged secretion from the bronchi.
- Sometimes use of broncho-dilator medicines is beneficial. It helps to expand the bronchial tubes. In case of fever, a short course of antibiotic therapy will help in resuming the function of alveoli back to normal.