Chest seals treat penetrating chest wounds by closing the hole, preventing air from being drawn into the chest cavity where it collapses the lung and, unrelieved, progresses to tension pneumothorax. Gunshot and stab wounds to the chest are among the injuries where immediate, correct treatment most changes survival, and the chest seal is the trained first response. Combat medics, EMS providers, law enforcement, and TCCC-trained civilians all stock them.

Stocked options include vented and non-vented occlusive seals from trusted brands like North American Rescue, whose HyFin line is a widely fielded standard, and Safeguard Medical, in single seals and twin packs sized for entry and exit wounds.

Vented versus non-vented is the core distinction. Vented seals incorporate one-way channels that let trapped air escape the chest while blocking inflow, directly addressing tension pneumothorax risk, and current TCCC guidance favors them; non-vented seals fully occlude and remain in service, but require monitoring for developing tension. Twin packs exist for a practical reason: penetrating trauma often has an exit wound, and both holes need sealing. Adhesive quality is the critical feature in the field, because a seal must bond to skin that is wet, bloody, or hairy, so gel adhesives engineered for those conditions are worth the cost. Always check the casualty's back; the wound you found first may not be the only one.

Chest seals belong beside decompression needles in the respirations layer of a kit, ride standard in every IFAK, and pair with trauma shears to expose the wound fast.