Thermal provocation to evaluate microvascular reactivity in human skin

Abstract

With increased interest in predictive medicine, development of a relatively noninvasive technique that can improve prediction of major clinical outcomes has gained considerable attention. Current tests that are the target of critical evaluation, such as flow-mediated vasodilation of the brachial artery and pulse-wave velocity, are specific to the larger conduit vessels. However, evidence is mounting that functional changes in the microcirculation may be an early sign of globalized microvascular dysfunction. Thus development of a test of microvascular reactivity that could be used to evaluate cardiovascular risk or response to treatment is an exciting area of innovation. This mini-review is focused on tests of microvascular reactivity to thermal stimuli in the cutaneous circulation. The skin may prove to be an ideal site for evaluation of microvascular dysfunction due to its ease of access and growing evidence that changes in skin vascular reactivity may precede overt clinical signs of disease. Evaluation of the skin blood flow response to locally applied heat has already demonstrated prognostic utility, and the response to local cooling holds promise in patients in whom cutaneous disorders are present. Whether either of these tests can be used to predict cardiovascular morbidity or mortality in a clinical setting requires further evaluation.

Camphor Induces Cold and Warm Sensations with Increases in Skin and Muscle Blood Flow in Human

“…[9][10][11] Minson et al explained that a rapid increase in skin blood flow is induced by local heating mediated by the axon reflexes and that a slower increase is induced by nitric oxide (NO).…”

“…The warm sensation induced by local heating of the skin increases skin blood flow, while the cold sensation induced by local cooling decreases skin blood flow. [8][9][10][11] However, application of menthol, which induces a cold sensation, increases skin blood flow. 12) In the present study, we also examined blood flows in the skin and muscle to explore the effects of camphor on blood flow.…”

Assessment of Human Skin Microcirculation and Its Endothelial Function Using Laser Doppler Flowmetry

“…They are used to investigate the mechanisms involved in the local cooling and heating (Johnson & Kellog, 2010;Minson, 2010), as well as in clinical practice to determine microvascular (dys)function in different diseases.…”

Assessment of microvascular and metabolic responses in the skin

“…Secondarily, nitric oxide is released generating a smooth muscle vascular relaxation and increase of the local microvascular blood flow, which is dependent on endothelial function. A plateau of the response is reached after 20-30 minutes (Kellogg, 2006;Minson, 2010;Minson et al, 2001). An attenuated response to local heating has been reported in patients with type 2 diabetes (Fredriksson et al, 2010;Vinik et al, 2001).…”

“…The response is characterised by an initial decrease in skin blood flow, followed by a short-term transient increase. After the transient vasodilation a progressive sustained vasoconstriction is observed (Minson, 2010). The mechanism is complex but appears to be mediated by an adrenergic response (Thompson-Torgerson et al, 2007) in combination with decreased nitric oxide synthase (NOS) activity (Hodges et al, 2006).…”