Measurement of cutaneous inflammatory reactions using a scanning laser-Doppler velocimeter

The performance of a new scanning laser-Doppler velocimeter (LDV), which can rapidly measure blood flux over a large area of skin without contact with the skin surface, was compared with that of a conventional laser-Doppler instrument. The vascular response was measured to a range of doses of UVB, and dilutions of contact allergens and sodium lauryl sulphate. The detection threshold of the scanning LDV was equal to, or lower than, that of the conventional instrument. For allergic contact hypersensitivity reactions (ACH), the coefficient of variation was significantly less using the scanning LDV. The scanning LDV allowed accurate measurement of the change in area that occurs with increasing intensity of inflammatory reaction. For ACH reactions the area of inflammation continued to increase at dilutions where blood flux had reached a plateau. The flare area was found to increase linearly with log dose of histamine with no change in blood flux.