Which Side to Decompress with a Chest Seal
Apply the chest seal directly over the open chest wound on the injured side—the side with the penetrating injury—not the opposite side. 1
Understanding the Pathophysiology
The question of "which side to decompress" reflects a fundamental misunderstanding of chest seal application. A chest seal does not decompress the chest; rather, it seals the open wound to prevent air entry while ideally allowing trapped air to escape. 1
Key Physiologic Principles
- Air enters the pleural space through the chest wall defect during inspiration when intrathoracic pressure becomes negative (creating a "sucking chest wound") 1
- The goal is to increase airflow resistance through the chest wall defect so it exceeds resistance through the trachea, allowing proper lung ventilation 1
- The greatest danger is creating a tension pneumothorax by preventing air from exiting the pleural space 1
Proper Application Technique
Location of Application
Place the chest seal directly over the open wound on the injured hemithorax. 2, 3
- If there is an entry wound on the anterior chest and an exit wound on the back, seal both wounds 2
- The seal goes on the side with the injury, not the contralateral (opposite) side 1
Type of Dressing Recommended
The 2024 American Heart Association guidelines recommend three reasonable options: 1
- Leave the wound exposed to ambient air
- Apply a clean, nonocclusive, dry dressing (gauze, part of a shirt)
- Apply a specialized vented chest seal
Vented chest seals are superior to unvented seals because they prevent tension pneumothorax development when ongoing air accumulation occurs. 4, 5 In a swine model, unvented chest seals led to tension pneumothorax after approximately 1.4L of air injection, while vented seals prevented this complication entirely. 4
Critical Monitoring Requirements
If any dressing is placed, continuously monitor for worsening breathing and immediately loosen or remove the dressing if respiratory status deteriorates. 1
Signs of Tension Pneumothorax Development
- Decreased air movement on the affected side 1
- Worsening dyspnea or severe breathlessness 6, 3
- Hypotension 1
- Tachycardia 3
Loosening or removing the dressing may relieve tension pneumothorax by allowing trapped air to escape. 1
Common Pitfalls to Avoid
- Never apply a fully occlusive dressing without a venting mechanism, as this can create fatal tension pneumothorax 1, 3
- Do not confuse chest seal application with needle decompression—these are different procedures for different indications 2
- Do not apply the seal to the wrong (uninjured) side—it must cover the actual wound 1
- For small wounds (stab wounds, most handgun wounds), air leak may not significantly impair respirations, but larger defects from high-velocity rifles, shotguns, or blast injuries benefit more from sealing interventions 1