Dynamic characteristics of laser-Doppler flux in normal individuals and patients with Raynaud’s phenomenon before and after treatment with nifedipine under different thermal conditions

Abstract

The study was aimed at choosing an appropriate characteristic of laser-Doppler flux (LDF) data for (1) distinguishing patients with Raynaud’s disease from normal controls and (2) evaluating the effect of nifedipine under different thermal conditions. We checked the reliability of three characteristics of nonlinear dynamics as statistical dimension ${\mathit{D}}_{\mathit{s}}$ , correlation dimension ${\mathit{D}}_2$ and power-law index PLI. Their values depended heavily on the thermal condition. The most reliable characteristics that enabled us to distinguish the patients from normal controls and the effect of nifedipine under definite thermal condition proved to be ${\mathit{D}}_{\mathit{s}}$ and PLI. The latter is simple for computation and is thus recommendable for clinical practice. ${\mathit{D}}_{\mathit{s}}$ and PLI were higher in patients with Raynaud’s compared to normal controls and diminished during the transitions from low to high temperature. However, the characteristics used were unable to distinguish significantly Raynaud’s I from Raynaud’s II patients.