We assessed the utility of a 3-grade classification of photoplethysmography (PPG) with cold water provocation test in Raynaud phenomenon (RP). A total of 35 patients with RP and 38 healthy volunteers were recruited. In healthy volunteers, PPG was measured twice at intervals of 30 minutes for evaluating reproducibility of test. Percentage variation of the PPG amplitude in post- versus precold provocation was expressed on a 3-grade scale at 1, 3, and 5 minutes (reflection index: RI) in patients with RP. The improvement pattern of the PPG (IPPPG) was evaluated by summing the score differences from RI1 min to RI3 min and RI5 min. After a therapeutic period of 8 weeks with nifedipine, the decreases in posttherapeutic RI3 min and RI5 min were statistically significant (P < .05). Subgroup analysis of IPPPG showed statistical significance in patients with negative fluorescent antinuclear antibody (P < .05). The analysis of cold-provoked PPG waves demonstrated and quantified improvements in peripheral arterial circulation in RP.
Keywords: Raynaud phenomenon; improvement pattern of PPG; photoplethysmography; reflex index.