Skin blood flow measurements on the breast areola.

Blood flow and thermally insulated skin temperature were measured in the aerolae of normal breasts by means of the non-invasive transient thermal clearance method. Both parameters showed high variability among different women, but also showed typical dependence on the subject's age: the two parameters were constant up to age 50, and then showed a decrease at higher ages. The decrease can be attributed to the normal decrease of tissue blood flow at higher age and to atrophy of the breast glandular tissue after menopause.

Power spectrum analysis of spontaneous fluctuations in the photoplethysmographic signal.

Direct measurement of variability in the peripheral circulation was performed by means of photoplethysmography, which provides assessment of blood volume in tissue and systolic blood volume increase. Both parameters showed oscillations at a relatively low frequency, about 0.02 Hz, and a relatively high frequency, about 0.