With this therapy, surgeons close the incision with standard staples, apply a strip of bridge dressing (GranuFoam, made by KCI), and cover the area with clear occlusion tape. The vacuum device (V.A.C. Therapy, made by KCI) is then applied at 75 mm Hg of continuous suction; in patients having a stoma, the stoma is returned after the device is in place.
In the study, the vacuum device was left on until postoperative day 5 or 7, and was removed before patients were discharged, according to Dr. Bonds.
Overall, 27.2% of the patients developed a surgical site infection. The rate was 12.5% in the group given incisional negative-pressure wound therapy, compared with 29.3% in the group given standard care.
In a multivariate analysis, patients in the negative-pressure wound therapy group were 68% less likely to develop a surgical site infection (odds ratio, 0.32; P = .04).
The only other independent predictor of this outcome was diabetes mellitus, which was associated with roughly a doubling of risk (OR, 1.98; P = .03).
"There are several proposed mechanisms for why this therapy would work," Dr. Bonds noted. The device prevents the incision from coming into contact with the surrounding environment, and decreases patient mobility and shear forces on the wound.
"In addition, the continuous suction seems to remove infectious material and the interstitial fluid, thereby decreasing the wound edema. Studies have also shown that the wound vacuum device increases vascularity to the wound, which would seem to help it heal as well," she said.
Dr. Bonds disclosed no relevant conflicts of interest. One coinvestigator has an affiliation with KCI.