Negative pressure wound therapy is a wound management system for chronic open subcutaneous or intra-abdominal wounds. Some popular commercial systems include V.A.C. therapy (KCI, San Antonio) and the Chariker-Jeter wound-sealing kit (Smith and Nephew, London). Within ob.gyn. and gynecologic oncology, they have use in the management of postoperative superficial wound dehiscence from routine surgery and in the management of the open abdomen.
The primary benefit of negative pressure wound therapy (NPWT) is the acceleration of wound healing. Postoperative superficial wound dehiscence can occur as a result of surgical factors such as wound infection and subcutaneous seroma/hematoma or systematic factors such as poor nutrition and wound ischemia.
Acceleration of wound healing results from the design of the NPWT systems. They consist of semipermeable dressings (foam), sealed with an adhesive sheet that is connected to a portable pump. By the application of –50 to –175 mm Hg of continuous or intermittent suction, the edges of the wound are drawn together, and this deforming process promotes tissue remodeling at the cellular level. Other potential benefits of negative pressure are increased blood flow, a decrease in mediators of inflammation, and an increase in collagen organization via changes in wound biochemistry.
Dr. Kemi M. Doll
An alternative to NPWT would be traditional gauze dressings, which can also be applied in the case of superficial wound dehiscence. These are changed up to three times a day, however, and this can result in significant patient discomfort, caregiver difficulties, and prolonged healing of weeks to months. In contrast, NPWT dressings are changed once every 2-3 days. They are also versatile and can be fit to traditionally shaped abdominal wounds, as well as difficult to dress vulvar and groin wounds (J. Obstet. Gynaecol. Can. 2011;33:1031-7).
In a series of 27 gynecologic oncology patients in whom NPWT was employed after primary wound–healing failure, there was a 96% reduction in the size of the wounds with a median number of therapy days of 32 (range, 3-88). The majority of these patients were also managed as outpatients without complication (Gynecol. Oncol. 2004;92:586-91).
There are some contraindications to NPWT that should be considered. The major, and perhaps most common, is an ongoing wound infection.
A wound that needs to be evaluated at least daily to assess the response to antibiotic therapy or need for debridement should not be managed with NPWT until the wound is deemed stable. There should be no devitalized tissue present in the wound upon application of the NPWT. If any necrotic tissue is present, then wound debridement is warranted until only well-vascularized tissue remains.
Another contraindication is the presence of malignant tissue in the wound. Negative pressure can promote this tissue growth and lead to chronic nonhealing. Other considerations would include adhesive allergies and fragile skin due to chronic steroid use or collagen vascular disorders, as NPWT can lead to skin necrosis.
Dr. Paola A. Gehrig
Finally, the involvement of vital organs, such as exposed bowel, is a contraindication to the NPWT systems, as constant suction can promote fistula formation or hemorrhage. However, in the setting of an open abdomen after trauma surgery, there has been the development of intra-abdominal wound management systems that may be appropriate.
Although rare in obstetrics, gynecology, and gynecologic oncology, delayed abdominal closure may be necessary. This can occur after reoperation for bowel injury, in cases where bowel wall edema and increased intra-abdominal pressure preclude closure, or in cases of massive hemorrhage (for example, ruptured ectopic pregnancy) where patient instability necessitates rapid termination of the surgical case. These wounds can be managed with temporary abdominal closure techniques such as retention sutures, a Bogota bag, or loose packing (World. J. Surg. 2015; 39: 912-25).
The negative pressure systems developed for these instances are the V.A.C. abdominal dressing (KCI), Renasys NPWT (Smith and Nephew), and ABThera open abdomen negative pressure therapy (KCI). They consist of a perforated plastic sheet with foam attachments that is placed directly in the abdomen to cover the intestine. This is then covered with an adhesive dressing that is cut to accommodate the suction attachment for the negative pressure pump. This setup is easily applied and taken down, and therefore facilitates frequent abdominal washouts until true facial closure can be achieved.
There are many benefits to NPWT for the management of superficial and deep wound dehiscence in the ob.gyn. or gynecologic oncology patient. NPWT should be considered primarily with any surgical wound healing by secondary intention.
Dr. Doll is a third-year fellow in gynecologic oncology at the University of North Carolina at Chapel Hill. Dr. Gehrig is professor and director of gynecologic oncology at the university. The authors reported having no relevant financial disclosures.