Atelectasis: Causes, Clinical Presentation, and Management

Pulmonary Atelectasis: Collapsed Alveoli

Atelectasis is the collapse of alveoli, reducing gas exchange. It can affect a subsegment, lobe, or entire lung.

Mechanism-Based Classification

Type	Mechanism	Common Causes
Resorptive (Obstructive)	Airway blockage → distal air absorbed	Mucus plug (post-op, asthma, CF), tumor, foreign body, blood clot
Compressive	External pressure on lung	Pleural effusion, pneumothorax, tumor, enlarged lymph nodes, abdominal distension
Contraction (Cicatrization)	Fibrosis pulls lung inward	TB, radiation, ARDS, connective tissue disease
Adhesive (Surfactant Deficiency)	Loss of surfactant → ↑ surface tension	RDS (preterm), ARDS, smoke inhalation, massive transfusion
Passive (Relaxation)	Loss of contact between pleural layers	Pneumothorax, large effusion

Risk Factors

• General anesthesia (↓ FRC, suppressed cough, supine), prolonged bed rest, smoking, obesity, neuromuscular disease, chest/abdominal surgery, COPD, CF.

Clinical Features

• Often asymptomatic if small/slow.
• Dyspnea, tachycardia, hypoxemia (refractory to O₂ if shunt), fever (post-op), decreased breath sounds, dullness to percussion, tracheal deviation (toward collapse).

Diagnosis

• CXR: Volume loss, displacement of fissures, elevated diaphragm, crowding of vessels, opacity.
• CT: Confirms, identifies cause (endobronchial lesion).
• Bronchoscopy: Diagnostic (visualize obstruction) + therapeutic (lavage, biopsy, stent).

Management

• Prevention (Perioperative): Pre-op incentive spirometry, early mobilization, adequate analgesia, lung expansion maneuvers.
• Treatment: Treat cause (bronchoscopy for mucus/tumor, chest tube for effusion/pneumothorax).
• Airway Clearance: Chest physiotherapy, incentive spirometry, CPAP/BiPAP, mucolytics (acetylcysteine/DNase).
• Positioning: Upright, affected side up (for unilateral).