Comparison of vacuum and conventional wound dressings for full thickness skin grafts in the minipig model

The aim of this study was to compare vacuum and conventional dressings and to follow revascularization with laser-Doppler spectroscopy and histological evaluations. In six minipigs, full thickness skin grafts were harvested on both sides of the back and transplanted to the contralateral site. One site was covered with a classical cotton dressing, the other with a vacuum dressing. For 10 days, oxygen, haemoglobin, flow and velocity levels were measured by laser-Doppler spectroscopy. Data were analyzed with ANOVA. Histological evaluation included haematoxylin and eosin (H&E) as well as CD31 immunohistochemical staining. Oxygen levels were significantly reduced in the vacuum dressing group compared with the classic dressing group during the first 3 days after transplantation. Haemoglobin levels were slightly, but significantly, higher in the vacuum dressing group over the whole observation period. On the second and third day after transplantation single capillaries were detectable in the histological evaluation. Starting from the fourth day, capillary number increased. Similar results for the classical pressure dressing and the vacuum dressing were observed. The present experimental model provides a standardized and reliable test system for evaluating revascularization of full thickness skin grafts in conjunction with growth factors and other enhancers of revascularization.