What is reexpansion edema?

What is Reexpansion Pulmonary Edema?

Reexpansion pulmonary edema (RPE) is a rare but potentially life-threatening complication that occurs when a collapsed lung is rapidly reinflated after drainage of air or fluid from the pleural space, resulting in fluid accumulation in the lung parenchyma due to increased capillary permeability and reperfusion injury. 1

Pathophysiology

The mechanism of RPE involves multiple factors that lead to pulmonary injury:

• Increased capillary permeability is the primary mechanism, caused by reperfusion injury of the previously hypoxic lung tissue 1
• Mechanical vascular stretching during rapid reexpansion contributes to endothelial damage 1
• Ischemia-reperfusion injury with free radical production damages the lung parenchyma 2
• Local production of neutrophil chemotactic factors such as interleukin-8 (IL-8) amplifies the inflammatory response 1

Risk Factors

Several clinical factors increase the likelihood of developing RPE:

• Duration of lung collapse: Prolonged collapse (particularly >7 days) significantly increases risk 1, 3
• Younger age: More common in young adults 1, 3
• Large extent of collapse: Massive pneumothorax or large pleural effusions carry higher risk 4, 3
• Rapid reexpansion: Quick drainage or early application of high suction precipitates RPE 1, 3
• Volume drained: Removal of large volumes (>1-1.5 liters) at one time increases risk 1

Clinical Presentation

RPE manifests with rapidly progressive respiratory symptoms shortly after chest tube insertion or thoracentesis:

• Acute dyspnea and tachypnea develop within minutes to hours after drainage 4, 5, 2
• Tachycardia and hypotension indicate cardiovascular compromise 3, 2
• Pink, frothy sputum is characteristic when present 3
• Hypoxemia with oxygen saturation dropping despite supplemental oxygen 3
• Chest discomfort and persistent cough may precede full-blown edema 1

The severity ranges from mild, self-limiting cases to rapidly fatal respiratory failure, though the condition may be more common and less fatal than historically believed 4.

Prevention Strategies

Controlled drainage is the cornerstone of RPE prevention:

• Limit initial drainage to 1-1.5 liters in adults, then clamp the drain for 1 hour before continuing 1
• Slow drainage rate to approximately 500 ml/hour to avoid precipitous pressure changes 1
• In children, limit to 10 ml/kg initially, then clamp for 1 hour 1
• Discontinue aspiration immediately if the patient develops chest discomfort, persistent cough, or vasovagal symptoms 1
• Avoid early suction application, particularly in primary pneumothorax that has been present for several days 1
• Use high volume, low pressure suction systems (5-10 cm H₂O) if suction is necessary, never high pressure systems 1

Management

When RPE develops, treatment is primarily supportive:

• High-flow oxygen or non-invasive ventilation (CPAP, high-flow nasal oxygen) is first-line respiratory support 4, 5
• Invasive mechanical ventilation may be required in severe cases; differential lung ventilation has been used successfully in refractory cases 6
• Corticosteroids (hydrocortisone) have shown benefit in case reports 5
• Diuretics are commonly administered though evidence is limited 3
• Bronchodilators and analgesics provide symptomatic relief 3

Prognosis

• Mortality ranges from 0-20% depending on severity and rapidity of recognition 3, 2
• Most cases are self-limiting with supportive care 2
• Early recognition and prompt intervention are critical for favorable outcomes 4, 5, 2
• Complete recovery is typical when managed appropriately 4, 5

Critical Pitfall

The most important pitfall is applying high negative pressure suction immediately after chest tube insertion in patients with prolonged lung collapse, as this dramatically increases RPE risk 1. Always drain large effusions or long-standing pneumothoraces in a controlled, gradual fashion with volume limitations and pressure monitoring when possible 1.