Physical factors and angiogenesis

Structural Microvessel Response in Dermis of Suction Blister Wounds on Upper and Lower Limbs in Healthy Volunteers

Structural aspects of the superficial microvasculature in suction blister wounds on forearm and lower leg in healthy volunteers (n=8) were studied by means of intravital microscopy. Functional microvessel lengths were quantitated, as was the number of established papillary loops and neovascularization sites. On the day of infliction, structural differences between the upper and lower limb wounds were small and insignificant, and the papillary loops spread out relatively richly over the surface. The changes that occurred over time on the two sites followed the same general pattern. Between day 2 and day 4 the loops became redistributed and more perpendicularly oriented within what appeared to be a larger tissue volume, and new vessel formation was increasingly evident. Redistribution and neovascularization occurred more quickly in the upper limb wounds, and the differences may be explained by the lower limb microvessels' being more fixed in the tissue.

Ilizarov wound closure method for traumatic soft tissue defects

Level of Evidence: V, Expert Opinion

[Vacuum-assisted closure therapy. Current status and basic research]

The gap between the broad clinical use of vacuum-assisted closure therapy (VT) and knowledge of the physiological mechanisms leading to its effectiveness is great. The value of the technique and its future development are dependent on research into these mechanisms. A meta-analysis evaluating the results of basic research on the effectiveness of VT was carried out based on peer reviewed publications. This is considered in relation to other therapeutic approaches of basic research to wound healing (growth factors etc.). Our study includes a concise description of the scientific background to the mechanisms of cell stimulation using basic work on tissue expansion, bone, vessel and nerve distraction as well as in vitro cell stimulation. Evaluation of the scientific data on all known effects of VT was made based on the results from experimental animal studies, the results of randomized clinical studies, observations on clinical applications and case reports. Assessment of the studies was based on design and significance as well as the appraisal of our own clinical experience. Data involving cellular effects (proliferation, synthesis, wound healing), systemic effects (mediators, systemic inflammatory disease), extracellular effects (perfusion, edema, local wound environment, stabilization, barriers) and complex effects of VT (inflammation, matrix function, blood supply) were examined. Systematic analysis of the data allows scientifically interested surgeons rapid access to the theme, the first, to this extent, extensive overview of the current scientific situation as well as a comprehensive bibliography for all areas involving the theme of mechanical cell stimulation. The authors list major areas for future research and encourage the development of multicenter studies.

Topical negative pressure therapy: mechanisms and indications

Topical negative pressure (TNP) therapy has emerged as a high-technology, microprocessor-controlled physical wound-healing modality. Complex effects at the wound-dressing interface following application of a controlled vacuum force have been documented. These include changes on a microscopic, molecular level and on a macroscopic, tissue level: interstitial fluid flow and exudate management, oedema reduction, effects on wound perfusion, protease profiles, growth factor and cytokine expression and cellular activity, all leading to enhanced granulation tissue formation and improved wound-healing parameters. Primary indications for clinical use have been documented and include traumatic wounds, open abdominal wounds, infected sternotomy wounds, wound bed preparation, complex diabetic wounds and skin-graft fixation. Whilst this therapy now forms an essential part of the wound healing armamentarium, extensive clinical trials are recommended to confirm efficacy and delineate its optimum use.

Serial measurement of blood flow in expanded tissue by laser Doppler velocimetry

This study provides additional information about changes in blood flow in expanded tissue as measured by laser Doppler. Five one-kilogram albino Hartley guinea pigs were implanted with commercially available hemispheric expanders. The expanders were inflated every 3 days on four successive occasions. Blood flow measurements were taken on each animal just before each inflation, immediately after inflation, and then at 1, 2, 3, 4, and 24 hours after expansion. Measurement of flow changes immediately after each inflation of the expander showed that, initially, blood flow in the tissue overlying the expander recovered quickly, but as the expansion process was continued, the flow did not return to baseline values so rapidly. This might be an indication that tissue expansion in patients could be carried out more rapidly during the initial inflations, with increasing recovery periods between inflations as the expansion process continued.