Comparative study of the microvascular blood flow in the intestinal wall, wound contraction and fluid evacuation during negative pressure wound therapy in laparostomy using the VAC abdominal dressing and the ABThera open abdomen negative pressure therapy system

To compare the changes in microvascular blood flow in the small intestinal wall, wound contraction and fluid evacuation, using the established V.A.C. abdominal dressing (VAC dressing) and a new abdominal dressing, the ABThera open abdomen negative pressure therapy system (ABThera dressing), in negative pressure wound therapy (NPWT). Midline incisions were made in 12 pigs, which were subjected to treatment with NPWT using the VAC or ABThera dressing. The microvascular blood flow in the intestinal wall, were measured before and after the application at topical negative pressures of -50, -75 and -125 mmHg, using laser Doppler velocimetry. Wound contraction and fluid evacuation were also measured. Baseline blood flow was defined as 100% in all settings. The blood flow was significantly reduced, to 646 +/- 67% (P < 005) after the application of -50 mmHg using the VAC dressing, and to 653 +/- 96% (P < 005) after the application of -50 mmHg with the ABThera dressing. The blood flow was significantly reduced, to 396 +/- 67% (P < 005) after the application of -125 mmHg using VAC, and to 405 +/- 62% (P < 005) after the application of -125 mmHg with ABThera. No significant difference in the reduction in blood flow could be observed between the two groups. The ABThera system gave significantly better fluid evacuation from the wound compared to the VAC system. There was no difference between the dressings regarding the reduction in blood flow, but the ABThera dressing afforded better drainage of the abdomen and better wound contraction than the VAC dressing.