A wound VAC in plain terms

If you are asking what a wound VAC is, the short answer is this: it is a small pump that applies gentle, steady suction to a wound through a sealed dressing. The medical name is negative pressure wound therapy, or NPWT.

A clinician may order it for a wound that is deep, drains heavily or is slow to fill in, such as a surgical wound that has opened, a pressure injury or a wound being prepared for a graft. It is not right for every wound. The treating clinician decides whether it fits yours.

The parts of the system

Knowing the parts makes a problem easier to describe over the phone.

  • Wound filler. Foam or gauze shaped to fit inside the wound.
  • Clear film. A thin adhesive sheet over the filler and nearby skin that makes an airtight seal.
  • Tubing. A tube running from a pad on the film to the pump.
  • Canister. A container on the pump that collects fluid drawn from the wound.
  • Pump. A rechargeable unit, often small enough to carry in a shoulder bag.

When the pump is running and the seal is good, the foam shrinks down and looks firm and wrinkled, a little like a raisin. That is normal.

How suction helps a wound

The suction pulls extra fluid away so the wound does not sit wet. It reduces swelling in the tissue nearby and draws the wound edges toward each other. It also encourages new, red, bumpy tissue (called granulation tissue) to fill a deep wound from the bottom up.

A wound VAC does not replace the rest of the care plan. Taking pressure off the area, managing blood sugar and eating enough protein and calories to heal still matter.

Day to day with the device

  • It runs nearly all the time. Ask how long the pump may be off or disconnected.
  • Dressing changes follow a schedule. A nurse or the treating clinician usually changes the dressing a few times a week, as ordered.
  • It needs power. Plug the pump in while you sit or sleep.
  • The canister fills. Ask who replaces it and where spares are kept.
  • It goes where you go. Route the tubing so it does not kink, catch on furniture or end up under your feet.
  • It makes some noise. A soft hum is normal. A new whistling or hissing sound may mean air is leaking through the seal.

Ask before the first shower. The guide to showering and bathing with a wound lists what to find out.

Questions to ask before you start

  1. Who changes the dressing, and on which days?
  2. Which number do I call about the pump, and which about the wound itself?
  3. What does each alarm mean, and which ones can I fix myself?
  4. What is the backup plan if the pump cannot be restarted?
  5. Who orders dressing kits and canisters, and when should the next delivery arrive?

If an alarm does go off, the guide on when to call about a wound VAC problem can help you sort out what to say.

What to report and when to call 911

Call the treating clinician if you notice any of these:

  • An alarm that will not clear, or a pump that stays off
  • Foam that has gone soft and puffy instead of firm
  • Canister fluid that turns cloudy, thick or foul smelling, or that increases sharply
  • Fever, chills, spreading redness, warmth or swelling around the wound
  • Pain that keeps getting worse while the suction is on
  • Blistered, raw or very itchy skin under the film

Bright red blood in the tubing or canister is never routine. Call the treating clinician right away, and call 911 for bleeding that is heavy or does not stop. Your instruction sheet should say what to do with the pump if you see blood, so ask about that on the first day.

How Gateway helps with a wound VAC at home

Across Greater St. Louis and the Metro East, Gateway arranges visits with partner clinicians who follow wounds treated with negative pressure. We coordinate the schedule and records and keep track of supply and equipment orders.

The treating clinician decides whether NPWT is appropriate, chooses the settings and decides when it should stop. To ask about wound VAC follow-up at home, call 314-325-0126 or send a request for care.

Common questions

Is a wound VAC the same thing as negative pressure wound therapy?

Yes. Negative pressure wound therapy is the medical term, and “wound VAC” is the common nickname, short for vacuum-assisted closure. Several companies make these pumps, and they differ in size, alarms and canisters. That is why the instructions for your specific device matter more than general advice, including this guide.

Does a wound VAC hurt?

Many people feel a pulling or tightening sensation when the pump first starts, and it usually eases within a short time. Dressing changes can be uncomfortable because the filler is lifted out of the wound. Tell the clinician how the changes feel. The page on pain and comfort during wound recovery explains how to describe pain clearly.

Can I sleep normally with the pump running?

Most people can, after a night or two of getting used to the hum. Ask where the pump should sit while you sleep and whether it should stay plugged in. Arrange the tubing so you do not lie on it or pull it when you turn over. If alarms wake you often, tell the care team, since they usually point to a seal or tubing problem.

Why would the clinician stop the wound VAC before the wound has closed?

NPWT is often a bridge, not the treatment from start to finish. Once the wound is shallower, cleaner and draining less, the clinician may switch to a regular dressing or plan a graft or surgical closure. Therapy may also be paused because of infection, bleeding, skin irritation under the film or a wound that has stopped improving.

Related pages

General information to help you talk with your own clinician. It is not medical advice, and the treating clinician makes every clinical decision. For a medical emergency, call 911.

Updated October 2026