In vivo comparison of electromagnetic and Doppler flowmeters: with special attention to the processing of the analogue Doppler flow signal

摘要: In acute experiments, instantaneous arterial flow tracings were obtained simultaneously with an electromagnetic (square-wave and pulsed field) a non-directional Doppler flowmeter at rest, during reactive hyperaemia isoprenaline infusion. A wide band signal was processed zero-crossing meter preceded without differentiator. The performance of both high low threshold meters also examined. combination differentiator gave the best results. this way, followed loss frequency information. Since weights amplitude respect to frequency, components, which normally are riding on frequencies, can be counted in meter. peak velocity readings femoral artery, however, significantly higher than those calculated from readings, band-pass filter preceding meter, necessitating situ calibration when absolute values required. Possible causes discrepancy discussed.