Negative Pressure Wound Therapy on Closed Surgical Wounds With Dead Space: Animal Study Using a Swine Model

Closed incisional wound surgery frequently leaves dead space under the repaired skin, which results in delayed healing. The purpose of this study was to evaluate the effect of negative pressure wound therapy (NPWT) on incisional wounds with dead space after primary closure by evaluating the fluid volume through the suction drain, blood flow of the skin, tensile strength, and histology of the wounds.

Bilateral 25-cm-long incisional wounds with dead space were created on the back of 6 pigs by partially removing the back muscle and then suturing the skin with nylon sutures. NPWT (experimental group) or gauze dressing (control group) was applied over the closed incision for 7 days. Analysis of the wound included monitoring the amount of closed suction drain, blood perfusion unit, tensile strength of the repaired skin, and histology of the incision site.

The drainage amount was significantly reduced in the experimental group (49.8 mL) compared to the control group (86.2 mL) (P = 0.046). Skin perfusion was increased in the experimental group with statistical significance compared to the control group (P = 0.0175). Collagen staining was increased in the experimental group. The tensile strength of the incision site was significantly higher in the experimental group (24.6 N at 7 days, 61.67 N at 21 days) compared to the control group (18.26 N at 7 days, 50.05 N at 21 days) (P = 0.02).

This study explains some of the mechanism for using NPWT in closed incision wounds with dead space. It demonstrates that NPWT significantly reduces drainage amount, increases skin perfusion, increases tensile strength, and has the tendency to promote collagen synthesis for closed wound with dead space indicating enhanced healing.