Negative Pressure Wound Therapy

Negative pressure wound therapy is a medical procedure in which a vacuum dressing is used to enhance and promote wound healing in acute, chronic and burn wounds. The therapy involves using a sealed wound dressing attached to a pump to create a negative pressure environment in the wound. Applying continued vacuum helps to increase blood flow to the area and draw out excess fluid from the wound. Depending on the wound type or location, the vacuum can either be applied continuously or intermittently. Negative pressure wound therapy can be used for a few days to several months at a time.

Uses

Several different types of wounds can benefit from negative pressure wound therapy such as:

• diabetic ulcers
• venous ulcers
• arterial ulcers
• pressure ulcers
• first and second degree burns
• chronic wounds
• wounds with large amounts of drainage
• surgical and acute wounds at high risk for infection

The Procedure

The dressing used for negative pressure wound therapy starts with sterile open-cell foam that is cut to size and packed into the wound. This foam acts as a sort of filter to keep any large particles (such as blood clots or dead, sloughed off tissue) from clogging the vacuum system. Once packed with foam, the wound is covered with an occlusive dressing, typically made of polyurethane. This dressing is clear in color, thin and creates an airtight seal around the wound. A pump is attached to the occlusive dressing and once negative pressure is applied, a vacuum environment is created.The pump can be programmed by a health care professional for strength of suction, amount of time it is to be applied and if it is to be intermittent or continuous. A chamber on the pump collects drainage and moisture is drawn away from the wound site.

In wounds that are not deep enough to accommodate the open-cell foam, sterile open weave gauze or other honeycomb dressing textiles can be applied beneath the clear polyurethane film instead. Dressings are changed every three to seven days or as needed. Negative pressure applied can range anywhere from -125 to -75 mmHg depending upon the wound and patient tolerance. Negative pressure wound therapy can be painful, particularly when dressings are changed. Once pressure is applied, most patients report a plateau in pain levels; however, the level of pain greatly depends upon the wound type, location and level of healing. Patients are often treated with pain medications prior to dressing changes and throughout negative pressure wound therapy.

Advantages over Other Treatments

Negative pressure wound therapy has increased in popularity over the past twenty years. While many research studies have shown evidence that negative pressure wound therapy improves wound healing, research is ongoing to determine the strength and length of therapy for specific wound types. Negative pressure wound therapy is a relatively non-invasive treatment option. The pump that creates the negative pressure is small and portable. Many wounds undergoing negative pressure wound therapy can be treated at home with a visiting home health care provider.

Who Is a Candidate

Candidates for negative pressure wound therapy include individuals suffering from:

• chronic ulcers caused by unrelieved pressure (bedsores), diabetes mellitus, venous insufficiency or arterial insufficiency
• wounds with copious drainage
• chronic wounds that have not responded to other treatments
• acute or surgical wounds at high risk for infection

Precautions

In order to be effective, negative pressure wound therapy must be monitored routinely to ensure that:

• the negative pressure seal has not been broken and leaks are at a minimum
• the tubing leading from the wound to the pump is free of kinks
• the drainage chamber is filling correctly and does not need changing
• the area around the wound remains unchanged
• the dressing is clean and not in need of changing

Additionally, a health care professional will evaluate an individual’s overall health to monitor for infection or a worsening condition. Other therapies likely to be used in conjunction with negative pressure wound therapy include:

• pain management
• debridement and irrigation of the wound
• antibiotic therapy
• nutrition evaluation
• IV fluids or other means of adequate hydration

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