Impaired Cutaneous Vasodilation And Sweating In Juvenile Grafted Skin

Abstract

Wounds, such as burns, seriously damage the skin, requiring, in many cases, the excision of damaged tissue and subsequent skin grafting. The excising process typically leaves little or no dermal layer containing the vascular network and sweat glands vital for thermoregulation. Although some degree of revascularization occurs in grafted skin, little is known regarding the effects of skin grafting with respect to the control of skin blood flow (SkBF) and sweating. PURPOSE The purpose of this study was to identify the consequences of skin grafting on endothelial dependent cutaneous vasodilation and sweating in juvenile (6–9 months post-surgery) split thickness grafted skin. METHODS Intradermal microdialysis membranes were placed in grafted skin and adjacent healthy skin allowing the local delivery of acetylcholine (1 × 10–7 to 1 M at 10 fold increments). SkBF and sweat rate were assessed over the semi-permeable portion of the membrane via laser-Doppler flowmetry and capacitance hygrometry, respectively. Cutaneous vascular conductance δCVC from baseline) and sweat rate (δSR from baseline) were calculated. SkBF data were mathematically modeled via nonlinear regression curve fitting to identify the dose of acetylcholine that caused 50% of the maximal vasodilator response (EC50). RESULTS CVC was significantly lower in grafted skin compared to healthy skin at acetylcholine doses greater than 10–4 M. There was a right-ward shift in the SkBF dose responses curve of grafted skin (EC50=−2.61± 0.44) compared to healthy skin (EC50=−3.34± 0.46). Increases in SR due to acetylcholine administration were significantly lower in grafted skin compared to healthy skin. Only minimal sweating was observed in grafted skin. CONCLUSIONS Reduced CVC and an elevated EC50 during acetylcholine administration suggest impairment of endothelial dependent cutaneous vasodilator responses in grafted skin. No appreciable sweating in the grafted skin suggests either abnormal or an absence of functional sweat glands in the grafted skin. These data suggest that juvenile split thickness skin grafts have minimal capability of contributing to thermoregulation. Such individuals may have increased risk of heat related injury if the grafted area covers a large fraction of the total skin surface. Project funded by NIH GM68865 & GM71092