Lobe Atelectasis

by Sam Malone

Lobe atelectasis, also known as the lobar collapse, is defined as the loss of lung capacity with decreased inflation of a lung lobe or a segment. Lobe atelectasis is usually a result of the obstruction of a lobar bronchus, an airway to a particular lobe in the lung. The condition is manifested in the radiological examinations as cloudiness or opacity and as the volume loss of the lobe.

Atelectasis is categorized into two types; these are as follows:
  • Primary atelectasis: The inability of the lungs to develop or expand completely at birth.
  • Secondary atelectasis: The complete or partial breakdown of a lung, usually after a surgery.
The signs of lobe atelectasis are as follows:

Primary Atelectasis

  • Asymmetry in vessel number
  • Fissure as edge

Secondary Atelectasis

  • Diaphragm elevation
  • Volume loss
  • Shift of ribs and mediastinum
There are four main lobe atelectasis patterns.
  • Right upper lobe (RUL)
  • Left upper lobe (LUL)
  • Right middle lobe (RML)
  • Right lower lobe (RLL)

Right Upper Lobe

In the right upper lobe collapse, the right helium, a wedge on the central part of each lung, is elevated. The disintegrated lobe bundles against the mediastinum, a space in the chest cavity in the middle of the lungs and the apex of the lung, the rounded upper portion of the lung. If the cause of the atelectasis is a centric obstructing mass, the changes may include fissure displacement, which may represent on chest radiographs and computed tomographic scans as a reverse S-shape called as the “reverse S sign of golden.”

Left Upper Lobe

The helium is moved upwards and the oblique fissure (major fissure) is moved forward. The connection of the anterior chest wall and the lobe is maintained. The left hemidiaphragm is raised to some extent. The dislocation of trachea and the movement of the anterior mediastinum mass are visible. The Lufsichel sign, a frontal chest radiolographic manifestation, is more common in the left upper lobe collapse.

Right Middle Lobe

The right middle lobe collapse is easily localized on the chest radiograph. The minor and major fissures progress close to each other and the lobe appears like a curved elongated wedge. The wedge retracts from anterior to posterior and medial to lateral directions. The mediastinum and the right hemidiaphragm are at normal points. The right helium is in order.

Right Lower Lobe

The manifestation is almost identical to that of the left upper lobe collapse. The integrated collapse of the right lower and middle lobe is characterized by the obstruction into the bronchus intermedius (intermediate bronchus). The displacement of the minor and major fissures, backwards and downwards, develops an opacity, which destroys the dome of the right hemidiaphragm. The anterior mediastinal mass is moved to the right side and the mainstem bronchus, right helium, upper lobar bronchus are shifted downwards.

The collapse of the entire lung is distinguished by a noticeable movement of the heart and the mediastinum to the affected part. The hemidiaphragm is shifted upwards and the characteristic is noticed on radiological tests solely on the left side by the elevated location of the stomach bubble.

Diagnosis

The diagnosis for the lobe atelectasis and the establishment of the collapsed lobe is done by chest radiographs (chest X-ray). However, in some cases computed tomography scanning (CT scan) is needed to further evaluate obstructive atelectasis. Magnetic resonance imaging (MRI) is rarely needed in the identification of lobe atelectasis.

Treatment

The treatment options for lobe atelectasis may include the following:
  • Chest physiotherapy
  • Nebulized dornase alfa (DNase) (to reduce infection and to improve lung function) 
  • Fiberoptic bronchoscopy 
  • Postural drainage
  • Chest wall vibration and percussion
  • Forced expiration technique (“huff technique”)

Complications

The complications of the condition may include:
  • Bronchiectasis
  • Acute pneumonia
  • Sepsis
  • Pleural effusion and empyema
  • Postobstructive drowning of the lung
  • Respiratory failure and hypoxemia
References:
http://www.ncbi.nlm.nih.gov 
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