The diagnostic utility of digital volumetric pulse plethysmography with the cold test in well known for the study of subjects vibrations exposed and symptomatic for acrosyndrome. In this study the authors show how to perform this test and how to analyse the results quantitatively (in particular the time-course of the vascular modifications during cold test) to improve the clinical interpretation and to allow a comparison during the years. The parameters studied are: the morphologic pattern of each wave; the entity, duration and the regression pattern of the modifications after cold test; the existence of hemorrheologic predisposing conditions to vasospasm. To each of these parameters it has attributed a score and all the scores together represent the sphygmic answer to the cold test.