How and When to Use Chest Seals

In the modern first aid kit, especially those built for use in locations that might become active shooter targets, there's an item called a chest seal. It might have a vent or it might not. It is probably wrapped in a thin, flat package and you might be wondering what exactly it does, not to mention what it looks like.

Becoming familiar with the items in a first aid kit is essential before you need to use the kit. Even if you haven't taken a first aid course, you should still take a few minutes to look over the items in a kit and learn how to use the supplies you don't recognize.

A chest seal is a very specific item that has only one use: to treat a sucking chest wound. Chest seals were esoteric additions to only the most extreme first aid kits as late as the beginning of the 2000s. Since active shooter and potential domestic terrorism situations have grown more common, you're likely to see them everywhere from schools to stadiums.

Chest Anatomy

The human chest has evolved to do three very important things:

  1. Protect the heart, lungs, major airways, and major blood vessels.
  2. Help move air in and out of the lungs (this is the money shot—pay close attention below).
  3. Help pull blood back into the heart. (This one is complicated and I'm not going to spend time on it here. Read up on how chest compressions work for a thorough explanation.)

Protection is the simplest one to see: the ribs act as a cage around the soft center of the chest to protect from blunt force injury. It's very effective, even if the ribs break. However, wouldn't it make more sense if the chest wall was solid, like the skull? Have you ever wondered why we have ribs instead of solid bone walls?

Moving air is the reason we have ribs instead of plates like in the skull. In order to pull air into the lungs and push it out again, the space inside the chest cavity has to be able to expand and contract. Ribs make that possible. Muscles stretched across and between the ribs pull them apart to expand the chest cavity or squeeze them together to contract it. When the chest cavity expands, air rushes in to fill it. When it contracts, air rushes out.

Chest Wounds Suck (At Least Some Do)

As long as the air only has one way in or out (the trachea), the lungs fill and empty just as they are supposed to do.

But when there's a new hole, air will be pulled into there as well as into the trachea. And when air is sucked in through a hole in the chest, it's called a sucking chest wound.

The only way to fix it is to seal the hole—with a chest seal. It's also useful to have a way for air that's trapped in the chest to escape, otherwise the cure for the sucking chest wound—stopping the air movement—leads to trapped air putting pressure on the lungs, what's known as a pneumothorax. To fix that problem, some commercially available chest seals come with vents to allow air out.

The following are common chest seals you can either buy or, in some cases, make yourself.

Halo Chest Seal

Halo chest seal

Photo from Amazon

The Halo Chest Seal was one of the first chest seals made commercially. It's no-frills and works very simply. It is essentially a sterile piece of plastic with an adhesive backing. To use it, "clean" the wound (basically just wipe off the blood and any dirt to make sure the adhesive will stick) and apply the chest seal.

Using a seal with no vent means you have to pay attention. If the patient experiences more severe shortness of breath or becomes drowsy, it might be because the chest seal is trapping air that's escaping from the lungs and causing a pneumothorax to develop. Some medics are able to vent the trapped air with a needle through the chest wall. Don't try that without proper training.

In the absence of being able to use the needle-through-the-chest trick, the simplest way to vent trapped air is to remove the chest seal. I know what you're thinking: why seal the wound if it'll cause a problem that's only fixed by unsealing the wound?

Because most of the time it's not going to happen. An army captain challenged the thinking of a non-vented chest seal for exactly the same reason. To test the treatment, the army developed a simulation of air leaking from the lungs. In that study, sealed chest wounds developed into pneumothoraces less often than unsealed chest wounds, even if the air was coming from the lung.

Asherman Chest Seal

Asherman chest seal

Photo from Chinook Medical Gear

So to prevent this whole issue, vented chest seals were invented. One of the oldest and most venerable is the Asherman chest seal. It has a vent that looks like a chimney.

To apply an Asherman seal, you have to line the vent up pretty squarely with the hole in the chest. In combat situations—meaning there's someone still shooting at you—taking a moment to line up the vent feels like torture. Once it's on, however, it works pretty well.

The vent is a one-way valve. It allows air to escape, but not to enter the chest. This solves the problem with a solid seal. Even if there's a hole in the lung, air will have a way out once the chest seal is in place.

Hyfin Vent Chest Seal

HyFin Vent Chest Seal

Photo from Chinook Medical Gear

Because some folks didn't like the idea of lining up the chimney during a gun battle, different types of chest seals were invented. These seals don't have to be perfectly positioned for the vents to work.

The Hyfin chest seal channels air in different directions so the wound can be positioned pretty much anywhere under the seal. The seal still works as a one-way valve.

Sometimes with vented seals, blood can get into the vents and coagulate, plugging the vents. The same rules apply as with non-vented seals: watch your patient. If the patient gets more winded or drowsy, it's a good sign he or she is developing a pneumothorax.

You Already Have One

Woman looking at first aid kit

Tetra Images / Getty Images

There are other vented chest seals and more are being invented every year. As we've learned, however, a vent is not always necessary. And when it comes to a non-vented chest seal, you probably already have one in your kit.

Look at your first aid kit. Do you have a sterile dressing that's packaged in plastic? In most versions, the packaging has clear plastic on one side and paper on the other. The idea is that you can peel off one side of the packaging and place the sterile dressing on the wound without contaminating it.

That means the inside of the plastic is also sterile, which means you have a ready-made chest seal right there. Open the packaging and throw out the dressing, then cover the chest wound with the plastic (sterile side touching the wound) and tape it down.

Some folks say if you tape the plastic on three sides, the seal will naturally "burp" air (when the patient exhales, air will escape and when the patient inhales, the plastic will suck in and stop air from entering). This is a tough one. It's quite possible that blood will act as a glue and cause the whole thing to work like a non-vented chest seal anyway. I recommend skipping the three-sided fanciness and just taping the thing in place well.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kheirabadi BS, Terrazas IB, Miranda N, et al. Do vented chest seals differ in efficacy? An experimental evaluation using a swine hemopneumothorax model. J Trauma Acute Care Surg. 2017;83(1):182-189. doi:10.1097/TA.0000000000001501

  2. Rescue Essentials. Halo Chest Seal.

  3. Rescue Essentials. Asherman Chest Seal.

  4. North American Rescue. Hyfin Vent Chest Seal Twin Pack.

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