Ever since we introduced the H*VENT vented chest seal, we’ve been getting the same question a lot: What’s the difference between the Bolin Chest Seal (BCS) and the H*VENT? The difference is the way both chest seals allow air and fluid to escape from an injured chest while preventing air to return.

A valved chest dressing, like the BCS, uses mechanical one-way valves to block air from coming into the chest. The valves never touch the body but rather sit above the chest. The valves are designed to be closed by default and open when a very small amount of air pressure (less than 1 mmHG) builds up behind the valve. Once the air pressure behind the valve becomes even with the air pressure outside the chest, the valve shuts and blocks air from coming back in. Vents on chest seals, like the H*VENT, work in a slightly different way.

Vents are designed to be open by default, allowing air and fluid to pass easily through the laminar channels and away from the chest injury. The vent closes when a negative pressure occurs in the chest, pulling the vent channels and vent area down against the chest seal or the skin to seal the wound. Because the vents rely upon collapsing material, the chance for air leaks to occur (allowing air to flow back into chest) is higher than with valves like the BCS. The H*VENT, however, seals against itself and against the chest, increasing the security of the seal and dramatically reducing the risk and amount of air leaks. Where vented chest seals are superior to valved chest seals is in allowing fluid to flow from the wound.

Valves, while more effective at maintaining negative intrapleural pressure to allow for partial lung reinflation, tend to restrict fluid flow through their mechanical structure while letting air pass. Laminar vented chest seals, with vents being open by design, can fluctuate in maintaining a negative intrapleural pressure but will allow fluids to pass through the laminar channels.