The Common Vein

Etymology

• Derived from the Latin word collapsus, meaning “fall together,” and the Greek word atelectasis, meaning “incomplete expansion.” The term refers to the complete collapse of an entire lung.

AKA

• Complete lung atelectasis
• Total lung atelectasis

Definition

What is it?

• Total lung collapse refers to the complete atelectasis of an entire lung, resulting in the absence of aeration in the affected lung and significant volume loss. It is often a life-threatening condition requiring immediate intervention.

Caused by

• Obstruction of the mainstem bronchus:
  • Mucus plugging
  • Foreign body aspiration
  • Endobronchial tumor
  • Post-intubation stenosis
• External compression of the lung:
  • Massive pleural effusion
  • Tension pneumothorax
  • Large intrathoracic mass
• Severe loss of surfactant in neonates (e.g., neonatal respiratory distress syndrome)

Resulting in

• Complete alveolar collapse in the affected lung
• Severe hypoxemia and respiratory distress
• Mediastinal shift and hemodynamic compromise in severe cases

Structural Changes

• Complete alveolar collapse with no residual air in the affected lung
• Severe displacement of mediastinal structures toward the collapsed side
• Compression of the contralateral lung in cases of significant volume loss

Pathophysiology

• Total lung collapse occurs when the entire lung becomes atelectatic due to obstruction of the mainstem bronchus or external compression. Air distal to the obstruction is absorbed, leading to alveolar collapse. In cases of pleural effusion or pneumothorax, external pressure forces the lung to collapse entirely. The complete loss of ventilation in the affected lung causes profound ventilation-perfusion mismatch, hypoxemia, and potentially life-threatening hemodynamic instability.

Pathology

• Collapsed alveoli with no air spaces
• Distorted bronchi and vessels pulled toward the collapsed lung
• Possible inflammation or fibrosis in chronic cases

Radiology in Detail

CXR

Findings

• Uniform opacification of the hemithorax corresponding to the collapsed lung
• Mediastinal shift toward the collapsed side
• Elevation of the hemidiaphragm on the affected side
• Crowding of ribs on the affected side

Associated Findings

• Contralateral hyperinflation due to compensatory mechanisms
• Potential pleural effusion or pneumothorax contributing to collapse

CT

Parts

• Entire lung parenchyma on the affected side

Size

• Significant volume loss involving the whole lung

Shape

• Homogeneous, dense opacity replacing the aerated lung

Position

• Complete collapse of the lung, typically with mediastinal structures pulled toward the affected side

Character

• Uniform opacity with sharp demarcation at the fissure or pleural boundary
• Displacement of bronchi and vascular structures

Time

• Acute onset in cases of obstruction or pneumothorax
• Chronic in cases of untreated obstruction or progressive fibrosis

Associated Findings

• Pleural effusion, pneumothorax, or evidence of a mass or obstruction

Other Imaging Modalities

MRI/PET CT/NM/US/Angio

• MRI: Rarely used but may assess associated soft tissue masses or lesions
• PET-CT: Useful for identifying malignant causes of bronchial obstruction or associated masses
• Ultrasound: Detects pleural effusion contributing to collapse

Key Points and Pearls

• Total lung collapse is a life-threatening condition requiring urgent evaluation and management.
• Common causes include mainstem bronchus obstruction, massive pleural effusion, or tension pneumothorax.
• Radiologically, it presents as complete opacification of the hemithorax with mediastinal shift toward the collapsed side.
• CT imaging is crucial for identifying the underlying cause, such as bronchial obstruction or pleural disease.
• Management involves addressing the underlying cause, such as bronchoscopy for obstruction, thoracentesis for effusion, or chest tube placement for pneumothorax.

White Out and Differential Diagnosis

• “White out” refers to complete opacification of a hemithorax on imaging, commonly seen in total lung atelectasis.
• Differential diagnosis for “white out” includes:
  • Total lung collapse (atelectasis)
  • Massive pleural effusion
  • Pneumonectomy
  • Extensive consolidation (e.g., pneumonia)
  • Large pulmonary mass or malignancy
  • Tension pneumothorax with contralateral mediastinal shift

Radiologic Findings of Total Lung Collapse

1. Increased Opacity:
   • The collapsed lung becomes densely opaque on imaging, as the air is absorbed from the lung tissue and the remaining lung is composed primarily of soft tissue.
   • The entire hemithorax (one side of the chest) may appear more opaque than the unaffected side.
2. Mediastinal Shift:
   • Structures such as the heart, trachea, and mediastinum shift toward the collapsed lung due to the loss of volume on that side.
   • This shift can be prominent, especially in cases of complete lung atelectasis without compensatory hyperinflation on the contralateral side.
3. Elevation of the Hemidiaphragm:
   • The diaphragm on the side of the collapsed lung is pulled upward due to the decreased intrathoracic pressure on that side.
   • The hemidiaphragm may be noticeably higher than the one on the unaffected side.
4. Rib Space Narrowing:
   • There is narrowing of the intercostal spaces on the side of the collapse, as the chest wall is pulled inward by the loss of lung volume.
5. Silhouetting of Adjacent Structures:
   • The normal borders of structures like the heart, aorta, and hemidiaphragm may be obscured by the collapsed lung, which now occupies a smaller, dense space adjacent to these structures.
   • This finding can help in determining the location of the collapse and distinguishing it from other causes of increased opacity.
6. Compensatory Hyperinflation of the Opposite Lung:
   • The unaffected lung may appear hyperinflated, as it expands to fill some of the space left by the collapsed lung.
   • The expansion of the unaffected lung may include herniation across the midline into the space of the collapsed lung.
7. Crowding of Pulmonary Vessels and Bronchial Structures:
   • Bronchi and vessels within the collapsed lung appear crowded and may be displaced toward the hilum.
8. Bronchial Cutoff Sign (If Visible):
   • On CT or sometimes X-ray, the cause of the collapse, such as an obstructing tumor or mucus plug, may be visible as an abrupt cutoff in the bronchus.

Additional Findings on CT

CT imaging provides a clearer view and may show:

• Direct visualization of the obstruction if there is a mass, mucus plug, or foreign body.
• Collapsed lung tissue appearing as a dense, triangular or wedge-shaped opacity.
• Possible pleural effusion on the affected side, sometimes seen in cases of malignancy or infection.

Causes

Common causes of total lung collapse include:

• Endobronchial obstruction: Often due to a tumor, mucus plug, or foreign body in the main bronchus.
• Malignancy: Lung cancer can obstruct a major bronchus and is a common cause of total lung collapse in adults.
• Large pleural effusion or pneumothorax: Can indirectly cause lung collapse by compressing the lung from outside.

Summary

Total lung collapse results in a range of radiologic findings, primarily marked by increased opacity, mediastinal shift, elevation of the hemidiaphragm, narrowing of the rib spaces, and potential compensatory hyperinflation of the opposite lung. These findings are important to identify the presence and side of the collapse and suggest possible underlying causes that may require further evaluation.

Total Left  Lung Collapse
Tension Pneumothorax

 

Total Right Lung Collapse
Tension Hydrothorax

Whole Lung Atelectasis Due to Obstruction

Total Lung Compressive Atelectasis
Effusion

White Out of the CXR with Passive Compressive Atelectasis of the Left Lung

White Out of the CXR with Passive Compressive Atelectasis of the Left Lung
48 year-old male presents with a dyspnea. CXR shows a total white out of the left chest with pulmonary congestion. CT scan shows a large left pleural effusion with total atelectasis of the left lung. Incidental note is made of premature calcific coronary artery disease.
Ashley Davidoff MD TheCommonVein.net

Links and References

Chat GPT Radiological findings of total lung collapse aka total lung atelectasis