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Wound Vac Therapy (Negative Pressure Wound Therapy)

What is wound vac therapy?

Wound vac therapy is a treatment used to help wounds heal. This treatment uses a medical device to create a vacuum, or negative pressure, to the wound. Wound vac therapy is also known as negative pressure wound therapy, vacuum-assisted closure, or VAC therapy.

Wound vac therapy is used to treat:

  • New wounds
  • Older wounds that have not healed
  • Incisions (cuts) from surgery

Some patients may need wound vac therapy for a few days. Others may need it for several months. Illness or its treatment can cause wounds to heal slowly. This is known as delayed wound healing. Slowed healing can result in infection and other problems.  

How wound vac therapy works

During wound vac therapy, a caregiver places a dressing (bandage) over the wound and applies suction with a machine. This therapy helps the healing process because it:

  • Removes fluid from the wound
  • Reduces swelling in the area
  • Helps the edges of the wound come together
  • Increases blood flow to the area
  • Reduces the number of dressing changes
  • Prevents the dressing from shifting easily with movement
  • Protects the wound and surrounding skin

What to expect during wound vac therapy

During wound vac therapy, the caregiver:

  • Cleans the wound and the skin around it
  • Places a dressing in the shape of the wound over the site
  • Covers the area with a clear adhesive film (drape) to seal the skin and protect the wound from infection
  • Places a vacuum tube over the film
  • Connects a tube to the small portable suction pump
  • Turns on the power to the wound vac machine

When the pump suction is on, it removes air from the site of the wound. For most patients, a wound vac does not cause added pain. When the suction starts and the dressing falls inward (collapses), your child may feel a slight pulling sensation. This usually goes away after a few minutes. Some patients may feel pain when the dressing pulls down, but this discomfort is similar to that of other wound-care procedures.

The suction also gently pulls fluid out from the wound. This can help clean the wound and reduce swelling. The fluid passes through the tube and collects in a canister attached to a pump, which stays on until the dressing change. The suction may run all the time (continuous) or only at certain times (cycle). Your care team will decide the amount of negative pressure your child needs.

Possible risks or side effects of wound vac

As the wound heals, the area may become itchy or uncomfortable. Rare risks of wound vac therapy include bleeding or infection.

Wound vac therapy at home 

If your child goes home with a wound vac machine, your care team will teach you how to use the pump. With a portable wound vac machine, patients can do most normal activities. Ask your provider how your child can do daily activities such as showering.

Parts of a wound vac machine

Most at-home (portable) wound vac machines have these main parts:

  • Therapy unit (pump) that creates suction
  • Canister or layer that collects fluid
  • Sterile plastic tubing that delivers the suction
  • A special foam dressing that is placed over the wound
  • A sticky film or protective layer (clear waterproof drape) that covers the dressing

See the user manual for help using your system. Check the device often and make sure that:

  • The pump is on
  • The foam dressing has collapsed
  • No air leaks from the drape or tubing
  • The battery is charged

Wound vac machine alarms

The therapy unit will sound a beep or an alarm if a problem occurs. Most alarms are due to one of the following reasons:

  • Pump is not active or is off
  • Low battery (always take power cord with you)
  • Leak, loss of suction, or blockage
  • Full canister that needs changing

Changing the canister and dressing

The care team will usually change a full canister at the clinic. They may teach you how to remove and replace the canister if needed. You may also learn how to repair leaks in the drape.

The dressing and tubing should be changed at least once a week (or more often, depending on the wound). Follow your care team’s directions. They may suggest medicine and other ways to manage pain during dressing changes.

When to call your care team

Let your care team know if your child's pain or discomfort increases or if there are signs of infection, such as:

  • Increased redness
  • Swelling
  • Fever

Call your doctor if you notice any of the following:

  • The fluid in the canister looks different in color or consistency
  • Bleeding increases
  • Pain, redness, or odor increase
  • The wound vac system is off for more than 2 hours
  • A skin rash and a lot of itching

Questions to ask your care team

  • Why does my child need wound vac therapy?
  • How long will my child need to use wound vac therapy?
  • How can my child shower during wound vac therapy?
  • How can I manage any pain that happens due to dressing changes?
  • Who should I call if my child has side effects such as bleeding or infection due to wound vac therapy?

Key points about wound vac therapy

  • Wound vac therapy, also known as vacuum-assisted closure or negative pressure wound therapy, is a treatment to help wounds heal.
  • A caregiver places a dressing over the wound and applies suction with a wound vac machine.
  • Your child might feel stretching or pulling, but this therapy does not cause added pain for most patients. Any discomfort is usually like other wound-care procedures.
  • If using an at-home wound vac machine, your care team will teach you how to use and care for the machine. Always follow your care team's instructions for wound care.
  • Contact your care team if you notice signs of infection, redness, bleeding, increase in pain, changes in the canister fluid, or problems with the machine that you can't fix.

Find more information on wound vac therapy and wound care

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Reviewed: May 2023