Finger systolic pressure during local cooling in normal subjects aged 20 to 60 years: reference values for the assessment of digital vasospasm in Raynaud's phenomenon of occupational origin.

Measurements of finger systolic pressure (FSP) during a standardized cold test (finger cooling to 30, 15 and 10 degrees C during 5 min ischemia) were performed on 103 healthy subjects divided into four subgroups according to age: 20-29 years (n = 22), 30-39 years (n = 32), 40-49 yr (n = 27), 50-60 years (n = 22). Among the age groups there was no difference in the reduction of FSP (FSP%) and in the digit-to-brachial systolic pressure index (DBI%) after cold provocation at 15 and 10 degrees C. Cold-induced digital vasoconstriction was more intense in smokers than in non smokers (P = 0.025). In the entire study population the lower normal limits of FSP% were 74% at 15 degrees C and 63% at 10 degrees C. Using an FSP%10 of less than 60% as a discriminating threshold between normals and patients with vibration white finger, the sensitivity of the cold test was 87% and the specificity was 100%. The findings of this study suggest the following considerations: (a) age does not seem to influence the digital arterial response to cold in healthy subjects; (b) smoking has a harmful effect on finger cold reaction in normal individuals; (c) the measurement of FSP during cooling is an accurate method of objectively diagnosing Raynaud's phenomenon of occupational origin.