Atelectasis

Original Editor - Hing Long Yip

Lead Editors  

Introduction

Atelectasis describes a state of the collapsed and non-aerated regions of the lung parenchyma. It is most commonly seen in the post-operative patients whose breathing mechanism is impacted by the procedure, pain, and prolonged recumbency. Less commonly, atelectasis is seen in people with conditions signify chronic sputum production or airway obstruction, such as COPD, bronchiectasis, and cystic fibrosis.

It is normally mistaken atelectasis as a diagnosis, instead, it is a clinical sign shown on a chest x-ray.

Etiology of atelectasis

Atelectasis may be the result of at least one of the following mechanisms:

Surfactant deficiency or dysfunction, the pulmonary surfactant, secreted by pneumocytes type II, covers the alveolar surfaces and it is composed of phospholipids, lipids, surfactant specific proteins, and calcium. The surfactant can modify alveolar tension with changes in the lung volumes, by reducing the alveolar surface tension, surfactant stabilizes the alveoli and prevents collapse. Therefore deficiency or dysfunction could result in the collapse of the alveolar space.

Resorptive atelectasis can arise due to intrinsic obstruction

Compression of the parenchyma

Common types of atelectasis

Atelectasis can be divided into two main types, obstructive and non-obstructive atelectasis.

Obstructive atelectasis: causes by blockage of the airway or multiple airways which limits airflow to the alveoli resulting collapse of the lung. It can arise due to

• Intrinsic factors such as mucus plug (cystic fibrosis, asthma, bronchiectasis, pneumonia...), polyps, papilloma, adenoma.
• Extrinsic factors such as foreign body, recurrent aspiration, and histoplasmosis

This type of atelectasis happens with acute pneumonia and chronic sputum production. Other conditions, such as malignancy and COPD, which impact on the patency of the airway can also cause obstructive atelectasis.

Obstruction atelectasis can impact parts of the lung or the entire depending on the location of the blockage. For example, when obstruction locates higher up or in bigger airways, a larger area of the lung would be affected due to the anatomy of the lung.

Non-obstructive atelectasis: is an umbrella term for other types that do not involve blockage of the airways. For example, compressive atelectasis, post-surgical atelectasis, round atelectasis, adhesive atelectasis, and replacement atelectasis. Amongst those, physiotherapy interventions can only be effective in treating compressive and post-surgical atelectasis.

• Compressive atelectasis: When there is an external force acting on the lung tissue preventing alveoli from expanding, such as pleural effusion.
• Post-surgical atelectasis: Usually due to the impaired breathing pattern due to post-operative pain. Other contributing factors including effects of anesthetics, type of surgery (usually abdominal or chest surgery), history of smoking, high BMI, prolonged recumbency, and increased sputum production.
• Adhesion atelectasis occurs due to surfactant deficiency, which can be seen in hyaline membrane disease in children and on acute respiratory distress syndrome (ARDS).
• Cicatrizion atelectasis is seen in fibrosis, the alveoli collapse due to the contraction of the scarred tissue.

Clinical Presentation

The signs and symptoms of atelectasis are often non-specific:

• Chest pain

• Shortness of breath

• Shallow breathing pattern

• Reduced chest expansion

• Increased respiratory rate

• Increased work of breathing

• Reduced breath sound on the ipsilateral side of auscultation. In cases of the upper lobe atelectasis, bronchial sounds may be heard, because of the proximity to the major airways.

• Hypoxia/hypoxemia

Once the diagnosis of atelectasis is suspected chest x-rays using anterior-posterior and lateral projections are mandatory to document the presence, extent, and distribution of atelectasis.

• CXR

Management / Interventions

Airway clearance techniques

As atelectasis can be caused by blockage of bigger airways, physiotherapy treatment to assist in airway clearance can improve atelectasis

Example of airway clearance technique: active cycle breathing techniques, supported cough, positioning, postural drainage

Breathing exercise

Incentive spirometry

Sustained maximal inspiration: is often used to prevent and manage atelectasis in abdominal and thoracic surgery patients. Its effects are often compared with incentive spirometry, and interestingly evidence has shown similar effects in SMI in improving breathing patterns, chest expansion, and thoracoabdominal asynchrony. Hence, it could be an alternative where incentive spirometry is unavailable.

Early mobilization

This fits in the picture of both post-operative patients and populations with acute respiratory conditions, such as acute pneumonia. When a patient is medically stable enough, the physiotherapist should assist with mobilization in accordance with the patient's status. Mobilization can include sitting up in bed, sitting over the edge of the bed, standing, marching at a spot, ambulation with/without aids.