ULTRASTRUCTURAL-STUDY OF THE DERMAL MICROVASCULATURE IN PATIENTS UNDERGOING RETROGRADE INTRAVENOUS PRESSURE INFUSIONS

Background: Retrograde intravenous pressure infusion (RIPI) of drugs, e.g. antibiotics, under arterial occlusion (Bier's block) allows high local tissue concentrations in the extremities. This technique is of p articular value in the antibiotic treatment of infected diabetic foot lesions. Objective: The aim of our study was to look for morphological changes of the dermal microvasculature induced by RIPI. Methods: In 7 patients with infected diabetic foot lesions, punch biopsies were tak en from the calf skin before and at the end of RIPI and studied by lig ht and electron microscopy. Results: RIPI induced a dilatation of veno us capillaries and postcapillary venules, loosening of contacts betwee n endothelial cells (EC) with focal formation of small gaps in the ves sel wall and a widening of the space between EC and pericytes. Lymphat ic vessels were markedly dilated. In contrast, arterioles did not exhi bit signs of morphological alteration. RIPI did not produce cellular d amage of blood and lymphatic vessels. Conclusions: The morphological c hanges of dermal vessels induced by RIPI are presumably due to a rapid rise in venous pressure. Our morphological observations support resul ts of previous hemodynamic and nuclear medical investigations, which s howed that RIPI enhances the filtration and diffusion of molecules int o the interstitium, leading to high local tissue concentrations. The v enous capillaries and postcapillary venules are involved in this proce ss in particular.