1 What Is Atelectasis?

Atelectasis is a condition in which one or more lobes of the lungs collapse or fail to inflate fully, thus reducing the capacity of the lungs to deliver oxygen to the body.

The lungs absorb oxygen from the atmosphere into the blood and then expel carbon dioxide from it. The oxygenated blood is carried to the brain and all other organs via the circulatory system. For gas exchange to occur, the alveoli must be open and filled with air. Alveoli are kept open by both surfactant and the elastic structure of the lungs. Surfactant normally ensures the alveoli remain inflated for efficient gas exchange. If they happen to close for any reason, such as mucus build-up, respiratory illness, or surgery, they hinder the gas exchange and are not able to participate in the process, which causes atelectasis. The more alveoli are closed, the less gas exchange takes place. Atelectasis can decrease the oxygen level in the blood. The body will compensate for this by constricting the blood vessels of the affected area, causing the blood flow to be redirected to the open alveoli.

Generally, adults with atelectasis recover quickly by doing respiratory exercises. But a persistent condition can cause a lung infection, such as pneumonia, so timely treatment is required, especially in infants, small children, and adults with respiratory illness. An obstructive condition due to a physical blockage of air flow causes the alveoli to collapse. When an alveolus collapses due to factors acting via other mechanisms, it is called non-obstructive atelectasis.

The condition is a common respiratory complication after surgery. It is also seen as a complication of other medical conditions like:

If only a small part of the lung is involved, it may not cause any specific signs or symptoms. When oxygen levels are low due to atelectasis, it results in shortness of breath.

Diagnosis is done through X-ray, and treatment of the condition is based on its cause and the severity of the collapse.  

2 Symptoms

Shortness of breath is the most common symptom of atelectasis. The severity of this symptom depends on the extent of collapse and how rapidly it develops; if a large area of the lungs is affected, it may result in severe shortness of breath.

Atelectasis may also cause an increase in heartrate and breath rate.

Lower levels of oxygen in the blood cause the skin to develop a bluish color, a condition known as cyanosis.

Symptoms may also depend on the cause of the condition. Rapid, shallow breathing and a cough are also symptoms of atelectasis. 

Signs and symptoms depend on the rapidity with which bronchial occlusion occurs, the presence or absence of complicated infections, and the size of the lung area affected. If a large area of lung collapses, it results in rapid bronchial occlusion, which causes pain on the affected side, sudden onset of dyspnea, hypotension, tachycardia, fever, and shock. A milder one may cause minor symptoms, or the atelectasis will develop slowly and may be asymptomatic.

Middle lobe syndrome may cause irritation in the middle right and lower right bronchi, which can cause a severe, hacking, non-productive cough

3 Causes

Obstruction of the airways and external pressure on the lungs are the main causes of atelectasis.

Anesthesia changes the pattern of breathing as well as the absorption of gases in the lungs. These conditions result in the collapse of air sacs in the lungs.

Some of the possible causes of obstructive atelectasis are:

  • Mucus plug: Mucus build-up in the airways due to respiratory illness or surgery cause atelectasis.
  • Foreign body: Inhalation of small objects like peanuts into the lungs, particularly in children, often results in the lungs collapsing.
  • Narrowing of airways: Constriction of the airways due to chronic conditions like fungal infections and tuberculosis may also lead to atelectasis.
  • Tumor: The presence of a tumor in the airways may lead to the collapse of one or more parts of the lungs.
  • Blood clot: Bleeding into the lungs may result in a clot, leading to collapse.

Non-obstructive atelectasis may be caused by:

  • Injury to the chest, which causes compression of the lungs, leading to atelectasis
  • Pleural effusion or accumulation of fluid in the lungs
  • Pneumonia
  • Pneumothorax, a condition in which air is present between the lungs and the wall of the chest, which may cause lung collapse
  • Scarring of the lung tissue

Surfactant production abnormalities can cause alveolar instability and result in atelectasis. They mostly occur with oxygen toxicity and ARDS.

The causes of resorptive atelectasis are:

  • Inflammatory etiology
  • Mucous plug
  • Malpositioned endotracheal tube
  • Aspirated foreign body
  • Bronchial obstruction from metastatic neoplasm (e.g., hypernephroma, melanoma, or adenocarcinoma of the breast or thyroid)
  • Bronchogenic carcinoma

The causes of relaxation atelectasis are:

  • Pneumothorax
  • A large emphysematous bulla

The causes of compression atelectasis are:

  • Loculated collections of pleural fluid
  • Chest wall, pleural, or intraparenchymal masses

The causes of adhesive atelectasis are:

  • Acute respiratory distress syndrome
  • Cardiac bypass surgery
  • Uremia
  • Hyaline membrane disease
  • Smoke inhalation
  • Prolonged shallow breathing

The causes of Cicatrisation atelectasis are:

The cause of replacement atelectasis is alveoli filled by a tumor or fluid.

Right middle lobe syndrome is recurrent in middle right lobe collapse or an airway infection, or it may be a combination of both. The bronchus in right middle lobe syndrome is long and thin. It has the poorest drainage or clearance, hence, mucus is retained and it is more prone to compression by the lymphatic system. Often, individuals with middle lobe syndrome are asymptomatic, although there have been cases of recurrent productive cough and right side pneumonia.   

The causes of rounded atelectasis are:

  • Asbestos-related pleural disease
  • Uremic pleuritis

Conditions that can decrease deep breathing, such as large doses of opiods or sedatives, or even chest or abdominal pain due to injury or pneumonia, can make deep breathing painful. Certain neurological conditions, such as chest deformities that limit chest movement, immobility, and abdominal swelling, can also affect deep breathing in an individual. Conditions that suppress a person’s ability to cough can contribute to atelectasis as well. After general anesthesia, it is common for a person to develop atelectasis, since general anesthesia temporarily suppresses a person’s cough and ability to breathe. Atelectasis is common after chest or abdominal surgery. Generally, after surgery, people take small, shallow breaths. Overweight or obese people also have higher chances of developing atelectasis.

The major risk factors of atelectasis include:

  • Impaired swallowing
  • Lung diseases, such as asthma, bronchiectasis, or cystic fibrosis
  • Premature birth
  • Shallow breathing caused by medications or rib injuries
  • Weakness of the respiratory muscles
  • Recent general anesthesia
  • Lung or chest surgery
  • Children under the age of three and adults over age sixty
  • Deep breathing impairment by neuromuscular disease
  • Being on a ventilator

4 Making a Diagnosis

The doctor can make a diagnosis after studying the person’s symptoms, performing a physical examination, and examining the settings in which the symptoms occurred.

Common tests used in the diagnosis of atelectasis are X-ray, CT scan, oximetry, and bronchoscopy.

A chest X-ray provides a detailed picture of the obstruction in the lungs as well as the changes in their structure. The imaging technique helps identify most physical obstructions inside the airway. Even factors exerting pressure on the lungs can be identified. Other techniques include:

  • CT scan: This is useful in measuring lung volumes. It helps detect atelectasis due to various causes, including tumors, which may not show up in a chest X-ray.
  • Oximetry: This is a technique that measures the oxygen saturation in the blood.
  • Bronchoscopy: This helps in both diagnosis and treatment of an obstruction in the airways. In this procedure, a small tube is inserted into the throat to see and possibly remove the obstruction, such as a mucus plug or foreign body. 

5 Treatment

If the atelectasis is minor, it does not require medical intervention, since it normally subsides on its own. However, if the case is severe, treatment is more focused on the re-expansion of the alveoli and treating the underlying condition.

Treatment of atelectasis is based on the cause of the condition. Atelectasis caused by an underlying condition is resolved by treating the disease. Minor cases of atelectasis may resolve without any specific treatment.

Chest physiotherapy helps expand the collapsed lungs and breathe deeply. This includes simple steps like:

  • Coughing
  • Beating or percussion on the chest to loosen the mucus build-up
  • Deep-breathing exercises
  • Lying with the head at a lower position than the chest

Shortness of breath is alleviated by supplementing oxygen. Surgery is recommended to remove airway obstructions.

Continuous positive pressure is another method to supplement oxygen in patients who are weak and have low oxygen levels. In this, air or a mixture of air and oxygen is delivered through a face mask even under continuous pressure. It is even done during exhalation. This is to prevent the lungs from collapsing. Antibiotics are given if a bacterial infection is suspected. Rarely, insertion of a breathing tube or mechanical ventilation is necessary.

  • Surgery: Atelectasis occurring after surgery is treated by deep breathing and coughing exercises. To facilitate recovery, the patient should keep moving and changing position in the hospital bed. Devices can be used to increase air pressure in the lungs.
  • External pressure: If atelectasis is caused by a tumor or fluids, it can be treated by removing the tumor or suctioning or draining the fluid.
  • Illness: Infections and other lung disorders can be treated using appropriate therapies.
  • Blockage: If the airway is physically obstructed, it can be removed through suctioning. If it can’t be removed by suctioning, it will have to be removed by bronchoscopy. Other methods that can be used are radiation therapy, laser therapy, surgery, or chemotherapy.

6 Prevention

Avoiding the risk factors helps prevent atelectasis.

Small objects should be kept out of reach of children to reduce the risk of obstructive atelectasis.

For people who smoke, the risk of atelectasis can decrease after surgery by stopping smoking at least six to eight weeks before the procedure. After surgery, take deep breaths, cough regularly, and move whenever possible. Other ways to prevent atelectasis are using devices that encourage voluntary deep breathing and doing certain exercises, such as changing positions. This increases the draining of lung mucus and other secretions. If there are conditions causing shallow breathing, they should be treated as soon as possible, since atelectasis can be prevented by persistent deep breathing and coughing.

Surgery is another major cause of this condition. Thus, taking adequate precautions to prevent atelectasis is important prior to any surgical procedure. 

7 Alternative and Homeopathic Remedies

Some alternative and homeopathic remedies for controlling the symptoms of atelectasis are:

  • Eucalyptus oil
  • Sesame oil
  • Ginger
  • Onion
  • Tomato

Breathing exercises help clean the airways and strengthen the muscles surrounding the air passages.

Neti with warm water and salt helps clear toxins and the airways, making breathing easier.

Antimonium tartaricum and hyoscyamus niger are also part of the homeopathic treatment of this condition. 

8 Lifestyle and Coping

Learn more about your condition and follow your doctor's instructions to cope with atelectasis.

Inhalation of eucalyptus oil and camphor relieves some of the symptoms of this condition.

A respiratory therapist may assist in keeping the airways free of phlegm. 

9 Risk and Complications

There are several risks and complications associated with atelectasis. The condition may lead to:

  • Low oxygen levels in the blood: The condition hampers the lungs’ ability to get oxygen to the alveoli.
  • Pneumonia: Unless atelectasis has been cleared, the patient is at a greater risk of developing pneumonia. Mucous in a collapsed lung may also cause infection.
  • Respiratory failure: If a small area of lung collapses, it is treatable, but loss of the whole lung or a lobe can be life-threatening, especially in an infant or in a person with lung disease.

Loss of a large part of the lungs may lead to respiratory failure. 


Usually, atelectasis in a small area of a lung is not life-threatening. The rest of the lung can make up for it; it will bring in enough oxygen for the body to function. However, larger areas may be life-threatening, especially in small children, babies, or in people with lung disease. If the airway blockage has been removed, the collapsed lung usually re-inflates slowly, although scarring or damage will remain. The outlook depends on the underlying condition.