Cutaneous Blood Flow in Psoriasis Measured by 133Xenon Clearance

By the radioactive, freely diffusible, inert gas 133 Xenon we studied the cutaneous blood flow in 15 cases of fresh, untreated psoriasis and in 10 normal subjects. In normal skin and in uninvolved skin in psoriatics the blood flow proved to be approx. 6.5ml/100 g tissue per min, while in the psoriatic plaques it was twice this value, viz. , about 12ml/100 g tissue per min. It is concluded (1) that the gross erythema, the slightly elevated skin temperature (by 1.5° C), and the microscopic evidence of vascular changes in psoriatic lesions are in fact based upon increased blood flow, (2) that, according to the results of the present technique, the cutaneous tissue of uninvolved skin in psoriatics does not have a greater blood flow than cutaneous tissue of controls, and (3) that the present method of determining the cutaneous blood flow following intracutaneous injection of 133 Xenon, calculating from the first, rapidly falling slope of the flow curve, is well-suited for clinical use, as the measurement need not be done for more than 10–15 minutes in order to calculate the cutaneous blood flow during the traumatic phase immediately after the injection.