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 V.A.C. abdominal dressing and the ABThera open abdomen negative pressure therapy system

Abstract

This study aimed 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 that were subjected to treatment with NPWT using the VAC or ABThera dressing. The microvascular blood flow in the intestinal wall was measured before and after the application of topical negative pressures of −50, −75 and −125mmHg 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 64·6±6·7% (P <0·05) after the application of −50mmHg using the VAC dressing, and to 65·3±9·6% (P <0·05) after the application of −50mmHg using the ABThera dressing. The blood flow was significantly reduced to 39·6±6·7% (P <0·05) after the application of −125mmHg using VAC and to 40·5±6·2% (P <0·05) after the application of −125mmHg using ABThera. No significant difference in reduction in blood flow could be observed between the two groups. The ABThera system afforded significantly better fluid evacuation from the wound, better drainage of the abdomen and better wound contraction than the VAC dressing.

Keywords: ABThera; Fluid evacuation; Microvascular blood flow; NPWT; Open abdomen; VAC.

© 2013 The Authors. International Wound Journal © 2013 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Figures

Figure 1

The microvascular blood flow in a small intestinal loop located at the surface of the anterior abdominal wall, when exposed to topical negative pressures of −50, −75 and −125 mmHg. The results shown are the mean values of six measurements ± SEM, expressed as a percentage of the baseline value. Statistical analysis was performed using the Mann–Whitney test. Significance was defined as P < 0·05 (*), and P > 0·05 (not significant, n.s.).

Figure 2

The microvascular blood flow in a small intestinal loop located centrally beneath the abdominal dressing, when exposed to topical negative pressures of −50, −75 and −125 mmHg. The results shown are the mean values of six measurements ± SEM, expressed as a percentage of the baseline value. Statistical analysis was performed using the Mann–Whitney test. Significance was defined as P < 0·05 (*), and P > 0·05 (not significant, n.s.).

Figure 3

Comparison of fluid removal using the two dressings, measured after 1, 5 and 10 minutes during NPWT at −50 (A), −75 (B) and −125 mmHg (C), using 1000 ml albumin solution. The results are shown as means ± SEM of six experiments. Statistical analysis was performed using the Mann–Whitney test. Significance was defined as P < 0·05 (*) and P > 0·05 (not significant, n.s.).

Figure 4

Comparison of wound contraction (wound width and wound length) using the two dressings, resulting from NPWT at −50, −75 and −125 mmHg. The results are shown as means ± SEM of six experiments. Statistical analysis was performed using the Mann–Whitney test. Significance was defined as P < 0·05 (*) and P > 0·05 (not significant, n.s.).