Non-invasive monitoring of finger arterial pressure in patients with Raynaud's phenomenon: effects of exposure to cold. We studied the effects of exposure to cold on finger arterial pressure (FAP) measured by a finger arterial pressure monitor in 15 patients with Raynaud's phenomenon and in 15 healthy volunteers. The cold exposure induced vasoconstriction of the peripheral vascular bed as judged by the plethysmograph of a pulse oximeter and had marked effects on FAP values compared with upper arm arterial pressure. Immediately after the cold exposure, FAP decreased significantly (P less than or equal to 0.01) in both groups. However, during the subsequent 20 min, FAP values increased in relation to upper arm pressure. Finally, FAP values were greater than upper arm pressure in the control individuals, but not in patients with Raynaud's phenomenon. These results have implications for non-invasive monitoring of arterial pressure by the finger pressure device. Clinically, significant problems may arise in the monitoring of FAP in patients with a systemic connective tissue disease affecting peripheral circulation. 