What is Right-Sided Atelectasis?
Right-sided atelectasis is a state of collapsed and non-aerated lung tissue in the right lung, which can occur through airway obstruction, external compression, or increased alveolar surface tension. 1
Definition and Pathophysiology
Right-sided atelectasis represents collapsed lung parenchyma on the right side that is otherwise structurally normal. 1 This is a pathological manifestation of underlying disease rather than a disease entity itself. 1
Primary Mechanisms
The right lung can collapse through three distinct pathways:
Obstructive atelectasis occurs when airways are blocked by foreign bodies, mucous plugs, broncholithiasis (calcified lymph nodes eroding into airways), or tumors causing resorption of alveolar air distal to the obstruction. 2, 3
Compressive atelectasis develops when external forces compress the right lung parenchyma, including pleural effusions, mediastinal masses, pneumothorax, or space-occupying intrathoracic lesions. 2, 3
Adhesive atelectasis results from surfactant deficiency causing increased surface tension in alveoli and bronchioli, preventing normal lung expansion. 1, 3
Clinical Patterns on the Right Side
Common Presentations
Lobar atelectasis on the right can involve the right upper lobe (which typically collapses superomedially), right middle lobe, or right lower lobe, each producing characteristic radiographic patterns. 3
Platelike (linear or discoid) atelectasis appears as horizontal linear opacities and can be seen with pulmonary embolism or post-operative states. 2
Rounded atelectasis (also called folded lung or Blesovsky's syndrome) presents as a mass-like opacity that may be mistaken for tumor, most commonly associated with asbestos exposure and characterized by the pathognomonic "comet sign" on imaging. 2, 4
Special Considerations
Combined right upper and middle lobe atelectasis usually stems from malignancy and represents a more concerning pattern. 4
Peripheral upper-lobe atelectasis on the right may collapse posterolaterally rather than in the typical superomedial direction, potentially resembling apical pleural fluid. 4
Diagnostic Approach
Chest radiographs using both anterior-posterior and lateral projections are mandatory to document the presence and location of right-sided atelectasis. 1
Direct Radiographic Signs
- Crowded pulmonary vessels in the affected right lung region 3
- Crowded air bronchograms 3
- Displacement of the right-sided interlobar fissures (minor and major fissures) 3
Indirect Signs
- Pulmonary opacification on the right 3
- Elevation of the right hemidiaphragm 3
- Rightward shift of mediastinal structures (or leftward if left-sided structures are pulled toward right-sided volume loss) 3
- Compensatory hyperexpansion of the remaining right lung or left lung 3
Clinical Significance
A critical pitfall is differentiating right-sided atelectasis from right lower lobe pneumonia, which can be a diagnostic dilemma. 1 The diagnosis of atelectatic pneumonia should be based on clinical signs and symptoms of infection coupled with identification of pathogenic bacteria in respiratory specimens, not on radiographic findings of atelectasis alone. 3
Impact on Outcomes
- Right-sided atelectasis commonly develops during anesthesia, with up to 15-20% of lung base regularly collapsed during uneventful anesthesia. 5
- Atelectasis can persist for several days postoperatively and serves as a potential focus for infection, contributing to pulmonary complications. 5
- In mechanically ventilated patients, regional assessment of right lung ventilation can guide therapeutic interventions. 6
Management Principles
Treatment varies based on the underlying cause and severity:
- Chest physiotherapy and postural drainage for mucous clearance 1
- Bronchodilator and anti-inflammatory therapy for reversible airway obstruction 1
- Bronchoscopy for persistent mucous plugs requiring direct removal 1
- Recruitment maneuvers with airway pressures of 40 cm H₂O can virtually eliminate atelectasis in anesthetized patients, though pressures of 20-30 cm H₂O are less effective. 7
A key caveat: recruitment maneuvers followed by ventilation with 100% oxygen cause rapid reappearance of absorption atelectasis; moderate FiO₂ (approximately 40%) should be used after recruitment to prevent recollapse. 5