Some types of wounds require a somewhat unconventional therapy looked through the eyes of a layman. One of those is a negative-pressure wound therapy or NPWT for short. Negative pressure wound therapy is a therapeutic technique used for the treatment and healing of acute or chronic wounds through the use of a vacuum dressing. Vacuum dressings are usually used to enhance the healing of second and third-degree burns through the application of sub-atmospheric pressure to the wounded area, thus promoting healing and regeneration of the injured tissue.
This type of dressing, or therapy, is accomplished by the application of a vacuum which promotes blood flow and draws out excess fluids, exudate, and infectious agents from the wounded area. It can be used intermittently or continuously, depending on the location and the type of the wound, as well as its size. One of the positive aspects of negative pressure wound therapy is that it can be used only for a few days, or, if needed, for several months.
Typical NPWT dressings are comprised of a vacuum pump, a gauze or foam dressing, drainage tubing, and, last but not least, an adhesive that seals the wounded area. Ever since the approval of NPWT by the FDA in 1997, the techniques and the system has evolved quite considerably. Nowadays, there are NPWT devices that are considerably more user-friendly, more efficient and safer, so they can be used with easy in hospitals, rehab centers, care facilities, and even homes of patients.
When and how is negative-pressure wound therapy used?
Negative pressure wound therapy can be used on several different types of wounds which include venous, arterial, and pressure ulcers, diabetic ulcers, chronic wounds, first and second degree burns, sometimes even third degree burns, wounds with large amounts of exudate, as well as acute and surgical wounds with moderate to high risk of infection.
So how to use it?
First of all, the procedure should start with sterile foam cut to the individual size and packed into the wound. In this case, the foam has a role of a filter that keeps large particles such as dead tissue and blood clots from clogging the vacuum. After the packing of the wound, it should be covered with an occlusive dressing, most commonly made of polyurethane, clear in color and thinly made so it can create an airtight seal around the affected area.
After that comes the attachment of the pump to the dressing, which creates a vacuum environment through the use of negative pressure. These pumps can be programmed for suction strength, duration of application, as well as the continuous or intermittent suction periods. The pump chamber draws in the moisture and drainage which is being pulled off from the wounded area. In the case of wounds that are not deep enough for open-cell foams, another option is the honeycomb dressings that can be placed under the polyurethane films.
These dressings should be changed every three to seven days, or more frequently if needed. The range of negative pressure can be from -125 to -75 mmHg, depending on the type of the wound and patient’s tolerance to vacuum pressure. Patient’s tolerance is of utmost importance here as negative pressure therapy can be quite painful, especially when changing the dressing. However, once the pressure has been applied, a wide range of patients experience a pain level plateau, although the location of the wound, as well as the level of the healing, play a crucial role in pain levels. The pain can be soothed with the use of pain medication prior to the changes of dressings, as well as through the duration of negative pressure therapy.
Positive aspects of negative pressure wound therapy
Negative pressure wound therapy has grown increasingly more popular in the past twenty or so years. There are studies that have shown that this type of therapy promotes the healing of the wounded area, however, there is an ongoing research the point of which is to determine the actual length and strength of such therapy for specific types of wounds.
One of the most important positive aspects of negative pressure wound therapy is that it is a relatively non-invasive option for treatment of various wounds. The pumps used are quite small and usually portable which makes them easier to use, which means that they can be used at patient’s home.
Risks and precautions
As with every type of dressing, negative pressure wound therapy comes with a set of risks. One of the most serious possible side effects of NPWT is infection and blood loss, however, these negative effects can be prevented by professionals if they pay attention to instructions for use, as well as the patient selection criteria, type of the wound, and thorough evaluation of the patient’s bleeding risk.
Patients with a history of postoperative blood clots, wound infection, and anticoagulation therapy fall into the high-risk category. These high-risk patients, if selected for the NPWT, must be taken care of in the appropriate health care facilities and settings with healthcare professionals available at all times if needed.
Dressing the wound prior to the application of a vacuum is also a necessary precaution. If dressed improperly, the wound can bleed profusely, putting the patient in danger. Additionally, infections may occur if pieces of dressing are retained in the wound, which can be prevented by carefully documenting the number of dressing pieces used for wound covering.
One should also take special care of the tube that leads from the wound to the pump and keeps it clean. Additionally, the drainage chamber should be filling steadily, and the negative pressure seal must not be broken or leak. A professional has to make sure that the area surrounding the wound is intact and to keep the dressing clean.
Some other factors should be taken into account before the commencement of negative pressure wound therapy. These factors include the debridement or irrigation of the wounded area, prescribing an antibiotic therapy to the patient, evaluating the patient’s nutrition habits and changing them if necessary, as well as proper pain management to ease the patient’s experience with NPWT.
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