Linear and nonlinear analysis of blood flow in healthy subjects and in subjects with Raynaud's phenomenon.

The paper presents analyses of the dynamics contained in the blood flow signals measured on healthy subjects and on subjects with primary Raynaud's phenomenon. Different signal processing methods are presented and discussed. The dynamics was evaluated in the time and frequency domains and in phase space. Additionally, changes in the basal value during temperature provocation were studied using multiresolution analysis. The analyses demonstrate differences between the blood flow dynamics in healthy subjects and subjects with Raynaud's phenomenon. Moreover, the observed decrease in the amplitude of oscillation in regions approximately 0.04 Hz and approximately 0.1 Hz suggests an impairment in the neurogenic and the myogenic regulation of the blood flow. The administration of nifedipine in subjects with Raynaud's phenomenon results in an increase in the basal value and in the amplitude of the blood flow component oscillating with the heart rate. However, it does not restore the dynamics to that found in healthy subjects.