Negative Pressure Wound Therapy

Negative Pressure Wound Therapy

Negative-pressure wound therapy (NPWT) is a therapeutic method employing a vacuum dressing to facilitate the healing process in acute or chronic wounds, as well as to expedite the recovery of first and second degree burns. This technique entails the controlled application of sub-atmospheric pressure to the local wound environment, achieved through a sealed wound dressing connected to a vacuum pump.

The utilization of NPWT in wound management saw a significant rise during the 1990s and 2000s, accompanied by a multitude of studies investigating its efficacy. While NPWT appears beneficial for diabetic ulcers and the management of open abdomen (laparostomy), further research is necessary to evaluate its effectiveness for other types of wounds.

NPWT stimulates wound healing by administering a vacuum through a specially sealed dressing. The ongoing vacuum facilitates the removal of fluid from the wound and enhances blood circulation in the area. The vacuum application can be continuous or intermittent, depending on the wound type and clinical goals.

Typically, dressing changes are performed two to three times weekly. Dressing options for NPWT encompass open-cell foam dressings and gauze, secured with an occlusive dressing to maintain the vacuum at the wound site. In cases where NPWT devices enable fluid delivery, intermittent extraction of used fluid aids in wound cleansing and drainage.

The general NPWT procedure involves fitting a dressing to the contours of the wound and sealing it with a transparent film. A drainage tube is connected to the dressing through an opening in the film, linking to a vacuum source. This transforms an open wound into a controlled, closed wound, while simultaneously evacuating excess fluid to enhance circulation and eliminate wound fluids. This fosters a moist healing environment and diminishes edema. NPWT is commonly utilized for chronic wounds or those expected to encounter challenges during healing, such as diabetic wounds.

Commercial NPWT products are typically categorized based on the type of dressing used: open-cell foam, gauze, or honeycombed textiles with a dimpled wound contact surface. Foam dressings are employed to fill open cavity wounds and can be tailored to fit wounds of various sizes. The dressing is applied to fill the wound, followed by the application of a film drape to create a seal around the dressing. A vacuum tube is connected through an opening in the film drape to a canister attached to a vacuum pump.

NPWT can be executed using standard medical supplies like open weave cotton gauze, transparent film, a flat drain, and tubing connected to a vacuum pump. The flat drain, encased in gauze, is placed on the wound, covered with a film drape to create a seal, and connected to the pump via tubing. Another dressing type involves layers of non-woven polyester, joined by a silicone elastomer, featuring a non-adherent wound contact surface composed of numerous small semi-rigid dome structures.

Irrespective of the dressing type used, once the dressing is sealed, the vacuum pump can be set to deliver continuous or intermittent pressures, with pressure levels varying based on the device and ranging between −125 and −75 mmHg, contingent on the material and patient tolerance. Pressure can be applied continuously or intermittently, as required.

The selection of dressing type depends on factors such as wound type, clinical objectives, and patient characteristics. Gauze may be preferred for pain-sensitive patients with shallow or irregular wounds, or wounds with undermining or explored tracts, while foam may be more suitable for wounds with regular contours, allowing easy customization and performing well for aggressive granulation formation and wound contraction objectives.