Vasomotor control in healed grafted skin in humans

Abstract

Do the vasomotor functions unique to skin recover in a skin graft? To determine whether locally mediated vasodilation and active reflex vasodilation recovery, we applied direct heating and whole-body heating, respectively. Also, presence of sympathetic cutaneous vasoconstriction was tested with application of lower body negative pressure (LBNP) during local heating. Subjects were six men who had been severely burned. Forearm blood flow (FBF) was recorded (venous occlusion plethysmography) in regions with healed split-thickness circumferential grafts. All subjects responded normally to local heating of the forearm (irrigation with 42 degrees C water). All but one showed cutaneous vasoconstriction in response to LBNP. Three subjects responded normally to whole-body heating with water-perfused suits (oral temperature elevation approximately 1.5 degrees C); two subjects had attenuated responses. No active vasodilation was normal cutaneous vasomotor functions return in (or under) split-thickness skin grafts, recovery and associated thermoregulatory function may be attenuated or absent, perhaps in relation to the survival of dermis.

Impaired Cutaneous Vasodilation and Sweating in Grafted Skin During Whole-Body Heating

“…These findings are in stark contrast to the findings of Freund and colleagues suggesting that cutaneous vasodilatory responses can be normal in grafted skin in some subjects. 5 These conflicting findings may be attributed to differences in methodology, as well as the maturity of the graft. Laser-Doppler flowmetry (probe and scanner) was used in the current study allowing the simultaneous assessment and comparison of cutaneous blood flow in grafted skin and ad- Figure 1.…”

“…Freund et al measured forearm blood flow via venous occlusion plethysmography as an index of cutaneous vasodilation, which would not differentiate between blood flow responses in the grafted and adjacent control skin. 5 Finally, the current study tightly controlled for maturity of the skin graft (5-9 months after surgery), whereas Freund et al investigated cutaneous vasodilatory responses in grafted skin from a small group of individuals (n ϭ 6) with a wide range of graft maturities (7 weeks to 5 years after surgery). 5 Attenuated increases in cutaneous blood flow in grafted skin may be the result of diminished sympathetic neural function (ie, inappropriate or absence of required sympathetic innervation and/or decreased neurotransmitter release).…”

“…5 Finally, the current study tightly controlled for maturity of the skin graft (5-9 months after surgery), whereas Freund et al investigated cutaneous vasodilatory responses in grafted skin from a small group of individuals (n ϭ 6) with a wide range of graft maturities (7 weeks to 5 years after surgery). 5 Attenuated increases in cutaneous blood flow in grafted skin may be the result of diminished sympathetic neural function (ie, inappropriate or absence of required sympathetic innervation and/or decreased neurotransmitter release). Consistent with this hypothesis, elevated baseline CVC in grafted skin during normothermia may be attributed to a lack of tonic sympathetic vasoconstrictor activity.…”

“…Most studies show an absence of sweating from split-thickness grafts. [5][6][7][8] This response is thought to be the result of a combination of the initial injury destroying sweat glands at the recipient tissue and a lack of sweat glands in the harvested tissue in most split-thickness grafts. 9 Altered autonomic control of skin blood flow and sweating may be responsible for the observed higher rectal temperatures in burn patients during a thermal challenge relative to nonburned counterparts.…”

“…However, these varied responses, coupled with a small subject number (n ϭ 6) with a wide range of graft maturities (7 weeks to 5 years after surgery), complicates the interpretation of these data. 5 In addition, Freund et al 5 assessed cutaneous vasodilation via forearm venous occlusion plethysmography, which does not allow for the regional assessment of cutaneous blood flow responses between grafted skin and adjacent control skin. Finally, little is known regarding the effects of harvesting skin on cutaneous vasomotor and sweating responses from the donor site, at which the cutaneous vascular bed, neural connections, and the duct portion of the sweat gland are disrupted.…”