Negative pressure wound therapy (NPWT) is the application of sub-atmospheric pressure to aid in the management of a wound. It can protect the wound and greatly aid in the healing process.

Topical Negative Pressure Wound Therapy, VAC

There are many different applications for negative pressure wound therapy. Negative pressure wound therapy is a technique that uses vacuum dressing to promote healing of both acute and chronic wounds. This method of wound management greatly helps heal wounds that are complicated by burns, infections, poor circulation, artificial implants, or exposed bone.

NPWT aids healing by improving the rate of angiogenesis, endothelial proliferation, capillary blood flow, basement membrane integrity, and decreasing edema and bacterial burden within the wound.

The Effectiveness of Negative Pressure Wound Therapy

A recent review was performed to assess the clinical effectiveness of NPWT. The review assessed the effectiveness of 17 studies using a specially constructed instrument.

Each study was given a rating (A (high), B (moderate), C (low) based on the effectiveness of the NPWT.

The review mainly focused on diabetic wounds with a minor focus on other wound types and concluded that treatment with NPWT can accelerate the healing of these wounds.

Applications

Vascular graft infections

Graft infections regularly occur following the placement of vascular and orthopedic grafts. This can severely affect old, immunosuppressed, or diabetic patients. Graft infections can also worsen cases of antibiotic resistance and increase the virulence of bacteria.

Antibiotic-resistant wound infections are more prevalent and problematic when there is an implanted graft in close proximity to the open wound.

Applying NPWT-based treatments in wounds that contain infected grafts has been shown to effectively aid in the healing of the wound.

Infections with vascular grafts occur in ~1-5% of all vascular bypass procedures. This results in a very high rate of amputation, up to 70%. NPWT has been effectively used as an alternative therapy to combat vascular graft infections.

Treatment aims to preserve the graft, debride (remove) any infected tissue, cover the exposed graft with muscle flap, and administer broad-spectrum antibiotics. It has been shown that NPWT worked well on patients who had severe groin wound infections that required debridement, resulting in polytetrafluoroethylene graft exposure.

The NPWT treatment improved the healing of these wounds and resulted in no further re-infections.

Orthopedic graft infections

Orthopedic implants are considered infected when they are exposed to the environment and to bacteria. In the cases of orthopedic implants, NPWT can be used as an intermediate step in order to close the wound or until the wound heals.

With orthopedic patients, infected wounds/implants can lead to severe complications. These infections are very devastating as they normally occur in areas with limited skin coverage, tend to involve bone, and can lead to limited joint and extremity mobility.

NPWT has been used in the setting of infected orthopedic wounds; it can be used as a bridge to skin grafting to facilitate reduced healing time. NPWT can also be used to promote the formation of granulation tissue in situations involving exposed orthopedic implants.

NPWT was applied to  various implants following surgical debridement. Once the wound developed adequate granulation tissue the NPWT was discontinued and the wounds were closed.

Complex abdominal wounds

Complex abdominal wounds are a huge problem for conventional surgical repair. They are very difficult to treat and have been associated with severe infections, poor healing, chronic inflammation, and loss of the abdominal domain.

NPWT has been used for the treatment of abdominal damage for a long time. Previous studies have focused on the use NPWT dressing in combination with wound closure by local skin flaps, or in healing of such wounds by secondary intention. This type of treatment has proved to drastically increase the healing speed and strength of the abdominal wounds.

The Versatility of Negative Pressure Wound Therapy

It is clear that NPWT is very helpful in many different clinical situations. It is a versatile treatment method that has provided effective treatment for many patients.

As wounds are heterogeneous in nature, using negative pressure wound therapy for their treatment is not a simple and straightforward process. Each patient will have different needs and this will have to be taken into account when planning on the treatment.

With more research into negative pressure wound therapies, new and innovative ways may be discovered in which they can be used, and the effectiveness of current treatments will undoubtedly increase.

Further Reading

• All Wound Healing Content
• Hydrogel Dressings
• Bioactive Glass Implants and Wound Care
• Diabetes and Wound Healing
• Preventing Infection in Open Wounds

Written by

Samuel Mckenzie

Sam graduated from the University of Manchester with a B.Sc. (Hons) in Biomedical Sciences. He has experience in a wide range of life science topics, including; Biochemistry, Molecular Biology, Anatomy and Physiology, Developmental Biology, Cell Biology, Immunology, Neurology  and  Genetics.