How and When to Use Chest Seals

Tips, Types, and Application

Chest seals are a type of bandage used for deep puncture wounds to the chest, neck, and abdomen. They play a critical role in triage first aid for these types of injuries. Chest seals are commonly used by first responders, including emergency medical technicians (EMTs) and military field medics, but can be used by anyone. They are simple to use and are included in many modern first aid kits.

Taking the time to learn about the supplies in your first aid kit—including chest seals—can help you know the types of injuries you're prepared to care for. It's important to know what items you'll have at your disposal before you need to use them.

Chest seals are simple, effective treatments that can save lives if you know when—and how—to use them. This information is important to know, even if you aren't a healthcare professional or in the military.

This article explains how and when chest seals should be used and why they are important.

How Does a Chest Seal Work?

The wall of the human chest is made up of muscles, cartilage, and bones (including the ribs) that protect vital organs, airways, and major blood vessels and help move air in and out of the lungs.

When we breathe, the muscles and cartilage stretched across and between our ribs make it possible for our chest to expand and contract as air moves in and out of our lungs through the trachea (windpipe). The rib cage stretches and organs and tissues inside the chest cavity shift as the lungs fill and empty. A hole in the chest wall (from a bullet or stab wound, for instance) can disrupt this closed system.

As the chest wall continues to expand and contract to breathe, air can be pulled into the chest through the wound. Additional air in the chest can put pressure on the lungs and make it hard for them to fill with air. This is a serious condition called a pneumothorax (Latin for "air in the chest"). It is also sometimes called a collapsed lung.

A wound that bubbles blood when a person breathes is a telltale sign that there is air in the chest that requires immediate treatment.

A chest seal does not stop a wound from bleeding. Rather, it works to close off the wound to prevent air from entering the chest cavity. Many versions also have a vent mechanism to allow any air that's already trapped in the chest to leave.

How to Use

As with any emergency situation where first aid is required, there are important steps to follow. After you have called 911, determined that the area is safe, and taken steps to prepare yourself by putting on protective gloves, it's time to assess the person's wounds.

If you see a deep puncture wound to the chest wall—or even suspect one—apply a chest seal. It is better to err on the side of caution and take proper steps to keep air out of the chest cavity. Applying a chest seal won't hurt the person, even if their wound isn't deep enough for air to enter the chest cavity.

It's important to note that some injuries—like gunshot wounds—have both an entrance and an exit. If the victim has been shot, it's important to see if the bullet exited the body. Both holes will need to be sealed to avoid a pneumothorax.

If you're providing emergency treatment for a chest wound, follow these steps to apply a chest seal:

  1. Dry the area as best as you can. Some chest seal kits include gauze for this purpose.
  2. Prepare the seal. If you are using a store-bought seal, this is as easy as removing the backing to expose the sticky part (adhesive). If you are making your own, prepare your material and cut pieces of tape so you have them ready.
  3. Apply the seal. Each seal will come with its own instructions.
  4. Monitor the person until emergency personnel arrives. If you notice breathing concerns, you may need to "burp" the chest seal or apply a new one.

The best time to apply a chest seal is after the patient exhales. This way, their chest has the least amount of air in it.

Vented Chest Seals

The purpose of a chest seal is to prevent air from entering the chest cavity through a wound to the chest wall. But what happens if air gets in the chest before you can apply the seal? Some chest seals have openings, called vents, that prevent air from getting in, but also allow trapped air to safely escape.

Types of Chest Seals

The following listing includes common chest seals available on the market and how to use them. It also says how you can make a chest seal yourself if you don't have one in your first aid kit.

Halo Chest Seal

Halo chest seal


The Halo Chest Seal was one of the first chest seals made commercially. It has a no-frills, simple design. 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. You may need to lift the edge of the seal slightly to "burp" it (release a little air), or apply a fresh seal.

Asherman Chest Seal

Asherman chest seal

Chinook Medical Gear

The Asherman chest seal has a vent that looks like a chimney. Once the seal is in place, the vent is a one-way valve that allows air to escape, but not enter, the chest. This solves the problem that a solid seal (such as the Halo) can present.

To apply this type of seal, you'll need to line the vent up with the hole in the chest. This process can be time-consuming, but ultimately it can be quite effective.

Hyfin Vent Chest Seal

HyFin Vent Chest Seal

Chinook Medical Gear

In emergency situations, time is of the essence. There isn't always time to perfectly position a chest seal's vent. Another vented dressing, the Hyfin chest seal, is a good alternative to the Asherman.

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 that allows trapped air to leave the chest cavity.

Sometimes with vented seals, blood can get into the vents and clot, plugging the vents. The same rules apply as with non-vented seals: Watch the patient. If they get more winded or drowsy, it's a good sign they could be developing a pneumothorax.

If emergency personnel has not yet arrived, you may need to apply a new seal.

Improvised Chest Seal

Woman looking at first aid kit

Tetra Images / Getty Images

If you don't have a pre-made chest seal in your first aid kit, don't worry. It's easy to improvise a chest seal with the supplies you have available.

One of the easiest ways to create your own is to use the packaging for a sterile dressing, like a roll of gauze. These typically have a paper side and a plastic side. The inside surfaces of the package are sterile (to protect the contents), which makes it a great candidate for an improvised chest seal.

Open the packaging and throw away the paper and the contents. Cover the chest wound with the plastic (sterile side touching the wound) and tape it down on all sides.

The same rules apply for an improvised chest seal: Monitor the patient for signs of breathing difficulties, and reapply a new seal if you need to.

A Word From Verywell

Emergency first aid situations can be frightening, especially if you aren't sure how to handle a serious injury such as a chest wound. A simple device like a chest seal can save a life when used properly.

Taking the time to understand how to use the supplies in your first aid kit before you need them can help you be prepared to aid in life-or-death situations.

Frequently Asked Questions

  • Will a chest seal stop bleeding?

    A chest seal is designed to prevent air from entering the chest cavity through a wound. Though it may slow bleeding down, it won't necessarily stop it.

  • What does it mean to burp a chest seal?

    Burping a chest seal involves allowing air to leave the wound covered by the seal. To burp a chest seal, gently lift a corner of the dressing. This will allow air to leave the space and can help the patient breathe more easily.

  • What is occlusive dressing?

    An occlusive dressing is a type of bandage that provides a barrier over a wound and does not allow air to pass through. A chest seal is a type of occlusive dressing designed specifically to treat chest wounds that could cause a pneumothorax.

  • When should you use a chest seal?

    Chest seals are used in the treatment of puncture wounds to the chest wall. If you are providing first aid and suspect an injury to the chest wall, applying a chest seal to the wound can prevent a pneumothorax, which is potentially life-threatening.

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.

Additional Reading

By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.