[Hemodynamic response of the digital artery to heat and cold in normal subjects, in systemic scleroderma and in Raynaud's disease].

Measurement of digital systolic pressure under hot and cold conditions provides objective data (in mm Hg) of the humero-digital gradient and of spasm induced by cold. Normal values are: digital systolic pressure at 30 degrees C: 94 +/- 12% of humeral systolic pressure; at 15 degrees C: 94.46 +/- 9.32%, and at 10 degrees C: 93.6 +/- 12% of digital systolic pressure at 30 degrees C. The significance of these two parameters resides in the fact that the humero-digital gradient is of etiological value in organic arterial disease, the specificity of the test being 94.4% in allowing distinction between Raynaud's disease and systemic sclerosis. The cold-induced spasm can provide quantitative evaluation of a clinical Raynaud's phenomenon with which it is correlated (specificity: 96%).