What is re-expansive pulmonary edema?

Re-expansion Pulmonary Edema: Definition and Clinical Entity

Re-expansion pulmonary edema (RPE) is a rare but potentially life-threatening iatrogenic complication that develops when a chronically collapsed lung is rapidly re-expanded following drainage of pneumothorax or pleural effusion, characterized by unilateral pulmonary edema in the re-expanded lung. 1

Pathophysiology

The underlying mechanism involves increased capillary permeability as the primary driver, caused by reperfusion injury to previously hypoxic lung tissue. 2 This process is amplified by:

• Mechanical vascular stretching during rapid re-expansion that damages endothelial cells 1, 2
• Local inflammatory response with production of neutrophil chemotactic factors such as interleukin-8 (IL-8) 2
• Ischemia-reperfusion injury when blood flow returns to the previously collapsed lung 1

The mechanism is not primarily related to absolute negative pleural pressure levels, but rather to the mechanical forces and inflammatory cascade triggered by rapid lung re-expansion. 1

Key Risk Factors

Duration of lung collapse is the most significant risk factor, particularly when collapse has been present for more than 7 days. 2 Other critical risk factors include:

• Younger age (more common in young adults, particularly males) 2, 3
• Rapid re-expansion, especially with high negative pressure suction applied immediately after chest tube insertion 1, 2
• Large volume drainage (>1-1.5 liters removed at one time) 1, 2
• Extent of collapse (massive pneumothorax carries higher risk) 3, 4

Clinical Presentation

RPE typically manifests within 1-2 hours after lung re-expansion, though delayed presentation up to 2.5 hours can occur. 3, 4 The clinical picture includes:

• Acute respiratory distress with dyspnea, tachypnea, and decreased oxygen saturation 3, 4, 5
• Pink frothy sputum (classic finding) 6, 5
• Chest discomfort and persistent cough 2
• Hemodynamic instability with tachycardia and potential hypotension 5
• Unilateral pulmonary edema on chest radiograph affecting the re-expanded lung 3, 4

The mortality rate ranges from 5-20%, making early recognition critical. 4, 6, 5

Critical Prevention Strategies

The cornerstone of prevention is controlled, gradual drainage with strict volume limitations:

• Limit initial drainage to 1-1.5 liters in adults, then clamp the drain for 1 hour before continuing 1, 2
• Maintain slow drainage rate of approximately 500 ml/hour to avoid precipitous pressure changes 2
• In children, limit initial drainage to 10 ml/kg, then clamp for 1 hour 2
• Avoid applying suction immediately after chest tube insertion, particularly in primary pneumothorax present for several days 1, 2
• If suction is necessary, use high-volume, low-pressure systems (5-10 cm H₂O) 2
• Stop aspiration immediately if the patient develops chest discomfort, persistent cough, or vasovagal symptoms 2

Management Approach

Treatment is primarily supportive and proportional to severity:

• Oxygen therapy as first-line intervention 4, 6
• High-flow nasal oxygen or CPAP for moderate cases 3, 4
• Mechanical ventilation for severe respiratory failure 6, 7
• Differential lung ventilation (asynchronous ventilation of each lung separately) for severe refractory cases 7
• Diuretics and corticosteroids as adjunctive therapy 5

The edema typically progresses for 24-48 hours but may persist for 4-5 days, with most cases showing radiological resolution within hours to days with appropriate management. 3, 6

Critical Pitfall to Avoid

Applying high negative pressure suction (>10 cm H₂O) immediately after chest tube insertion in patients with prolonged lung collapse dramatically increases RPE risk. 1, 2 This is particularly dangerous in young patients with large, long-standing pneumothoraces who have been present for more than several days. 1, 4 The practice of routine high-pressure suction application should be abandoned in favor of controlled drainage protocols with pressure monitoring when possible. 2