Negative pressure wound therapy

Photo of a nurse treating a wound (PantherMedia / Sanda Stanca) Negative pressure wound therapy can be used to help close poorly healing wounds and certain types of surgical wounds. Some studies suggest that this treatment can help wounds heal better.

Wounds are typically cleaned and then closed. Usually just an adhesive bandage is needed as a wound dressing for smaller wounds, which then close on their own. The edges of larger wounds can be sewn together, or closed with staples or adhesives, and then treated with a wound dressing. Wounds that can’t be closed directly because of their size or an inflammation can be treated with a wound dressing. Different kinds of dressings made of various materials may be used depending on the type of wound. They are used to keep the wound clean, protect it from infection and help it to heal.

Wounds that don’t close after several weeks despite treatment are considered to be chronic. Inflamed or chronic wounds are cleaned regularly. Dead or inflamed tissue is removed as well. This treatment is called “debridement.”

An extra treatment called negative pressure wound therapy (also referred to as vacuum-assisted closure or VAC therapy) may be recommended for some wounds.

Negative pressure wound therapy

In negative pressure wound therapy, the wound is sealed airtight using a special wound dressing made of a sponge material or gauze. A pump connected to the dressing by a thin tube removes the wound secretions, which lowers the pressure around the wound and causes the flow of blood to the wound to increase. It helps keep the wound moist too, which is also meant to improve the healing process. The wound dressing is usually changed regularly, depending on the type of wound being treated, among other things.

First (primary) and second (secondary) intention wound healing

Wounds heal in various ways, depending on the shape and size of the wound. The types of healing are typically categorized as follows:

  • First intention wound healing: Wounds edges that are even and close together can be joined, such as using stitches (suture) to close a cut made during surgery.
  • Second intention wound healing: The edges of a wound can’t simply be joined together if a patch of tissue is missing, severely damaged or dead, or if the wound itself is infected. The body first needs to produce new tissue to fill this gap. A procedure like a skin graft may be needed for the wound to heal.

Wounds can also heal by epithelial wound healing. Wounds that are limited to the top layers of skin heal quickly as the damaged tissue is replaced with new tissue without any complications or scarring.

Research results on negative pressure wound therapy

The Institute for Quality and Efficiency in Health Care (IQWiG, Germany) looked into whether negative pressure wound therapy has any advantages or disadvantages compared to standard wound treatment and care. The assessment handled wounds with first intention wound healing and second intention wound healing separately.

Negative pressure wound therapy for wounds with first intention wound healing

The IQWiG researchers found a total of 45 studies with usable results on the advantages and disadvantages of negative pressure wound therapy in first intention wound healing compared to the standard treatment (such as a conventional wound dressing). These studies looked at surgical wounds. Poor wound healing was expected in most of the patients who participated in the studies.

The initial results suggest that negative pressure wound therapy can improve wound healing:

  • The wound healed within six weeks in about 88 out of 100 people who had the standard treatment.
  • The wound healed within six weeks in about 95 out of 100 people who had negative pressure wound therapy.

In other words: An additional 7 out of 100 wounds were healed with negative pressure wound therapy.

The studies also suggested that negative pressure wound therapy helps to prevent milder infections.

Complications, especially serious ones, were equally common in both treatments. It’s not possible to tell which of the treatments resulted in less pain or shorter hospital stays: The studies showed conflicting results here. There was no difference in quality of life.

Negative pressure wound therapy in wounds with second intention wound healing

The IQWiG researchers found a total of 48 studies with usable results on the advantages and disadvantages of negative pressure wound therapy in second intention wound healing compared to the standard treatment.

Overall, the studies suggest that negative pressure wound treatment can also help to heal these wounds. They showed that:

  • The wound healed within six weeks in about 35 out of 100 people who had the standard treatment.
  • The wound healed within six weeks in about 46 out of 100 people who had negative pressure wound therapy.

In other words: An additional 11 out of 100 wounds were healed with negative pressure wound therapy.

The treatment shortened the time the patients spent in the hospital, too. Study participants who were given the standard treatment stayed in the hospital for an average of 23 days (median value). Those who had negative pressure wound therapy were able to leave the hospital home an average of five days earlier.

Pain and complications (and especially serious pain and complications) were equally common in both treatments. The same is true for the number of amputations. Life expectancy was the same in both treatment groups.

It's not possible to tell how negative pressure wound therapy affects quality of life: The studies showed inconsistent results. The effects on the patient’s need for assistance and care were not studied.

Possible advantages of negative pressure wound therapy

Overall, the results of the studies show that negative pressure wound therapy improves the healing of wounds in comparison to a standard treatment. Both involved a similar amount of side effects.

However, the researchers identified a number of further studies with unpublished results. It can’t be ruled out that these unpublished results show something else, so it’s possible that the advantages of negative pressure wound therapy may currently be overstated.