Facilitating laser Doppler measurements of cutaneous adrenergic vasoconstriction: a comparison of methods

Abstract

Detecting vasoconstriction in the skin of the human forearm is often difficult because cutaneous perfusion is usually low, even in the absence of vasoconstrictive agents. However, flow through "vasoconstricted" skin can be detected by increasing the background skin blood flow. The aim of the current study was to evaluate local warming and postocdusive reactive hyperemia as techniques for increasing background flow to facilitate laser Doppler measurements of cutaneous vasoconstriction in the forearm. Noradrenaline introduced by iontophoresis into the forearm of healthy volunteers initially reduced the peak hyperemic response (mean decrease in hyperemia 21 +/- 7%, p <0.01), compared with a saline control. However, vasoconstriction was unrelated to the dose of noradrenaline and was not detectable when the test was repeated, possibly because the peak of the normal hyperemic response decreased with repeated occlusions. When the forearm was warmed to 42 degrees C, noradrenaline introduced by iontophoresis produced dose-dependent vasoconstriction relative to saline control sites and skin not having undergone iontophoresis (greatest mean decrease 64 +/- 7%, p <0.001). Therefore, local warming is recommended over reactive hyperemia for facilitating laser Doppler recordings of cutaneous vasoconstriction in the human forearm.

Oscillation frequency of skin microvascular blood flow is associated with mortality in critically ill patients

“…The magnitude of RH response correlated well with the degree of physiological derangement. As adrenergic vasoconstrictors have been shown to decrease the peak RH response by more than 20%, it is conceivable that the higher dosages of norepinephrine infused in non‐survivors may have masked an increased RH response in these patients (19). An alternative interpretation is that the RH response remains intact, and the difference between survivors and non‐survivors is the result of the oxygen supply not reaching the tissue because of capillary perfusion failure in non‐survivors.…”

Transdermal iontophoresis as an in-vivo technique for studying microvascular physiology

“…This overrepresentation is most likely due to the low sensitivity of the laser Doppler technique in measuring baseline or decreased skin perfusion (Lipnicki and Drummond, 2001). This low sensitivity is caused by at least two effects.…”

The effect of cutaneous mast cell degranulation on sensitivity to heat

“…Noradrenaline was then introduced by iontophoresis at one of the capsaicin-treated compound 40/80 sites and at the saline site using a 20 mm diameter circular iontophoresis chamber (0.5 mM concentration of noradrenaline in the iontophoresis chamber; current strength 200 mA; current duration 60 s) ( Table 1). Iontophoresis of noradrenaline at this current strength and duration decreases local blood flow by approximately 60 % [25]. To investigate the nonspecific effects of iontophoresis, 200 mA was passed through a 0.9 % saline solution for 60 s at the second compound 40/80 site.…”