A microcomputer system for evaluation of laser Doppler blood flux measurements

Results of local skin perfusion measurements performed by laser-Doppler-fluxmetry (LDF) are generally expressed in terms of relative mean values of time constants of signal responses to various procedures. In addition, information is obtained from the frequency and amplitude of temporal signal variations. In this report, a microcomputer system designed for recording, storage, artifact elimination, evaluation, and documentation of LDF measurements will be described. This system consists of a desk-top computer with additional hardware necessary for digital data acquisition and acceleration of mathematical operations. A three-phase model defined by a control, a transient, and an effect interval was programmed in order to standardize calculations within the time domain. For spectral analysis of periodical signal fluctuations, an algorithm was implemented based on a Fast-Fourier-Transformation (FFT) in combination with an optional averaging of several spectra within the frequency domain. Clinical measurements performed on patients with peripheral arterial occlusive disease (PAOD) and healthy volunteers illustrate the features of the system.