Reference range and variability of Laser-Doppler-Fluxmetry.

The Laser Doppler technique (Laser-Doppler-Fluxmetry, LDF), a noninvasive method to estimate skin blood flow (LDF), is frequently used in research and clinical routine [1]. Here, the measurements were carried out with a new Laser Doppler system, the DOP-system, which allows to measure frequency spectra in four different frequency windows according to the velocities in venules (low velocity), capillaries (low to medium velocities), and in arteries (with high and very high velocities). However, the diagnostic reliability or the effectiveness of the LDF has not yet been evaluated sufficiently, which is indispensable, where medical diagnostics and therapy controls are concerned. For a valid interpretation of LDF values of individual patients, the knowledge of the reference range and the variability of the measured parameters is required.In four successive studies the reference range (62 apparently healthy subjects), the circadian variability (8 subjects), the variability from day-to-day (6 subjects) and over one year with monthly measurements (6 subjects) were evaluated.With the knowledge of the reference range, microcirculatory disorders can now be diagnosed using the DOP method. Following a standard measurement procedure there was no dependence of the measured data on the day or season of measurement.