Published: 18 Jun 2025

ICD9: 518.0      ICD10: J98.11      ICD11: CB40.2

Atelectasis, also known as pulmonary collapse, is the complete or partial collapse of a lung or lobe of a lung.
It occurs when the tiny air sacs (alveoli) within the lung become deflated or filled with alveolar fluid.

Think of it like a deflated balloon. The air sacs are no longer filled with air and can't participate in gas exchange (taking in oxygen and releasing carbon dioxide).

Here's a breakdown of the key aspects:

What collapses? The lung tissue. This can be a whole lung, a lobe (sections) of a lung, or even just small areas within the lung.
Why does it collapse? Usually because air is prevented from entering the alveoli, or the air is absorbed from the alveoli and not replaced. Sometimes, it's due to external pressure.
What does it do? It reduces the area of the lung available for gas exchange, which can lead to lower oxygen levels in the blood.

Causes of Atelectasis:

There are two main categories: Obstructive and Non-Obstructive.

Obstructive Atelectasis: This is the most common type. It's caused by a blockage in the airway (bronchus or bronchiole) preventing air from reaching the alveoli.
Mucus plug: This is the most frequent cause, especially after surgery, in people with lung diseases like cystic fibrosis or COPD, or those who are weak and have difficulty coughing.
Foreign object: A small object (like a peanut or toy) can be accidentally inhaled, blocking an airway. More common in children.
Tumor: A growth in the airway can obstruct airflow.

Non-Obstructive Atelectasis: This occurs when something *outside* the airway prevents the lung from expanding properly.
Surgery: Anesthesia and pain medications can reduce breathing depth and suppress the cough reflex, leading to mucus plugging and atelectasis. Being on a ventilator can also contribute.
Pleural effusion: Fluid accumulation in the space between the lung and chest wall (pleural space) can compress the lung.
Pneumothorax: Air leaking into the pleural space can also compress the lung.
Tumor: A large tumor outside the airway can compress the lung.
Scarring (Pulmonary Fibrosis): Scar tissue in the lung can restrict its expansion.
Surfactant deficiency: Surfactant is a substance that reduces surface tension in the alveoli, preventing them from collapsing. Premature infants often lack sufficient surfactant (Infant Respiratory Distress Syndrome).
Obesity: Excess weight on the chest can restrict lung expansion.

Symptoms of Atelectasis:

The symptoms can vary depending on the extent of the collapse and the underlying cause. Some people may have no symptoms at all. Common symptoms include:

Shortness of breath
Cough
Chest pain (often on the affected side)
Rapid, shallow breathing
Wheezing
Fever (sometimes)

Diagnosis:

Physical exam: A doctor may hear decreased breath sounds on the affected side.
Chest X-ray: This is the primary way to diagnose atelectasis.
CT scan: Provides a more detailed image than an X-ray.
Bronchoscopy: A flexible tube with a camera is inserted into the airway to visualize and potentially remove any obstruction.

Treatment:

Treatment depends on the cause and severity of the atelectasis. Options may include:

Incentive spirometry: Encourages deep breathing.
Chest physiotherapy: Techniques like postural drainage, percussion, and vibration to help loosen and clear mucus.
Coughing techniques: Controlled coughing to clear airways.
Nebulizers: Deliver medications to open airways or thin mucus.
Bronchoscopy: To remove obstructions.
Surgery: In some cases, to remove tumors or repair lung damage.
CPAP or BiPAP: To provide positive pressure to keep airways open.
Treatment of underlying cause: Addressing the underlying condition (e.g., pleural effusion, pneumothorax).

Complications:

If left untreated, atelectasis can lead to:

Pneumonia: Collapsed lung tissue is more susceptible to infection.
Respiratory failure: If a large portion of the lung is affected, it can lead to inadequate oxygen levels in the blood.
Permanent lung damage: Prolonged atelectasis can cause scarring and permanent lung damage.

In Summary: Atelectasis is a condition where a lung (or part of it) collapses, usually due to a blockage or external pressure. It reduces gas exchange and can cause breathing difficulties. Early diagnosis and treatment are important to prevent complications.