The combination of laser Doppler perfusion imaging and photoplethysmography is useful in the characterization of scleroderma and primary Raynaud's phenomenon

Objective: To investigate simultaneously skin perfusion and digital artery pulsatility of hands in patients with primary Raynaud's phenomenon (PRP) and systemic sclerosis (SSc). Methods: In 100 SSc patients, 92 PRP patients, and 80 healthy controls, perfusion and digital artery pulsatility of the hands were investigated by laser Doppler perfusion imaging (LDPI) and photoplethysmography (PPG), respectively. Results: Both the mean value of mean perfusion and the mean value of sphygmic wave amplitude were lower (p < 0.0001) in the PRP group than in the SSc group, and also in the SSc group compared with the healthy controls. A positive correlation (r = 0.95) was found between the mean value of mean perfusion and the mean value of sphygmic wave amplitude. A homogeneous perfusion distribution pattern was present in 95% of the healthy controls, 93% of the PRP patients, and 4% of the SSc patients. PPG shows a homogeneous pattern in 95% of the healthy controls, 93% of the PRP patients, and 28% of the SSc patients. LDPI and PPG showed a positive concordance (p < 0.05) in homogeneous pattern evaluation. In the SSc patients, no correlation (r = 0.38) was observed between the mean value of sphygmic wave amplitude and the mean value of mean perfusion of each finger. Conclusion: LDPI and PPG can provide useful information in distinguishing patients with PRP and SSc, although nailfold videocapillaroscopy (NVC) is the best method for analysing microvascular damage in rheumatic diseases.