Examination Of Facial Reflex Vasodilation In Young And Older Females Using Laser Speckle Contrast Imaging.

Aging is known to attenuate reflex forearm cutaneous vasodilation during passive heating. However, it is unknown whether facial reflex vasodilation is also impaired with aging in females who may report greater facial flushing with menopause. Facial skin is also innervated by various spinal nerves (dermatomes) and varies in microvascular density over the surface, which could influence cutaneous vasodilation differently across facial regions during passive heating. PURPOSE: To explore how facial reflex cutaneous vasodilation in response to whole-body passive heating in females is modulated across dermatomes and by age using laser speckle contrast imaging (LCSI). METHODS: 10 young (23 ± 3 years) and 10 older (70 ± 3 years) females underwent passive heating via a water-perfused suit to raise core temperature to 1.0 °C above baseline (36.9 °C ± 0.29). Steady-state heating was maintained for 60 minutes (+0.98 °C ± 0.08). LSCI was used to measure facial skin blood flux (quantified in perfusion units) at baseline and end-heating. Imaging flux was measured over the entire face and partitioned into regions of interest (~20mm2) to evaluate vasodilator responses across specific facial landmarks (eyelids, nose, lips), dermatomes (V1, V2, V3) and the left and right sides of the face. RESULTS: There was a significant main effect of heating on blood perfusion for the whole face pooled across age groups (+104% [87.3,121], P < 0.001). There was a significantly greater response to heating for skin corresponding to dermatome V2 (+99.4% [ 43.1, 155.8], P < 0.001) and the lower lip (+97.5% [1.32, 193.6], P = 0.03) relative to the whole face. There was no significant difference in responses to heating between the left and right sides of the face, nor any significant differences between age groups with respect to the whole face or partitioned regions of the face. CONCLUSION: LSCI captured the effect of whole-body passive heating on facial vasodilation in young and older females. Reflex vasodilation was not uniform across the face. It was greater in regions with higher nerve fiber and capillary density. These findings warrant further investigation into the influence of skin tissue characteristics on facial cutaneous vasodilation. Supported by: Natural Sciences and Engineering Research Council of Canada