NAILFOLD CAPILLAROSCOPY AND LASER-DOPPLER FLUXMETRY FOR EVALUATION OFRAYNAUDS-PHENOMENON - HOW VALID IS THE LOCAL COOLING TEST

Background: Since there is a need for an objective parameter of microc irculation in follow-up of patients with Raynaud's syndrome we evaluat ed the reproducibility of the reaction to a cold exposure test with na ilfold capillaroscopy and laser Doppler fluxmetry during a winter peri od. Patients and methods: 10 healthy subjects and 16 patients with pri mary Raynaud's syndrome were evaluated with nailfold capillaroscopy an d laser Doppler fluxmetry of the finger tips during and after a standa rdized cold exposure stress test. The measurements were repented in th e controls within 2 weeks, in the patient population twice within 24 w eeks. Results: in the healthy controls the percentage of capillaries w ith flow stop was stable (r = 0,785) and the duration of flow stop was reproducible (r = 0.993). Both parameters were significantly lower in controls than in the patients. The flow stop durations in patients va ried intra-individually to a great extent between the different weeks without any significant correlation. For all calculated laser Doppler perfusion and time parameters lye did nor find any significant differe nces between controls and patients not any consistent correlations in the intra-individual comparison within the different weeks for both, c ontrols and patients. Conclusion: Nailfold capillaroscopy during cold exposure is able to discriminate between healthy persons and patients with primary Raynaud's syndrome, bur seems to be of minor value for fo llow-up evaluation of patients because of intraindividual variations. Laser Doppler fluxmetry is invalid for both purposes when using the ap plied cold exposure test.