Increased 133xenon washout from cutaneous tissue in generalized scleroderma indicates increased blood flow

Blood flow in cutaneous tissue of the dorsum of the hand was measured by the local 133Xenon washout technique in 18 normal persons and in 26 patients suffering from generalized scleroderma of the acrosclerosis types. Flow values calculated from the accepted blood--tissue solubility coefficient (lambda) were 8.6 +/- 0.4 S.E.M. ml/100 g X min in normals and 14.5 +/- 1.1 ml/100 g X min in sclerodermic skin (i.e. increased by 69%). The difference was significant (p less than 0.001). Blood flow values in sclerodermic skin were directly proportional to the degree of dermal sclerosis. As lambda in sclerodermic skin is probably decreased due to a decreased fat content, it may not be correct to interpret these results as evidence of increased blood flow. A "worst case" was constructed in calculation of lambda using zero fat content for sclerodermic skin. Flow value was now 12.3 +/- 1.1 S.E.M. ml/100 g X min for sclerodermic skin, an increase of 43% compared with normal skin. It is probably only justified to use this "worst case lambda" in the group of severely involved cases of scleroderma. In these patients it yielded a flow value of 17.8 +/- 3.1 (N = 6) which, when compared with the flow value for normal skin, indicates an increase by 100% of the blood flow in severely involved sclerodermic skin.