| 摘要 |
<p>A non-invasive measuring system adapted to measure arterial blood flow in human beings is provided. A stable, strong magnetic field is produced in the region of the artery under measurement by a magnet suitably positioned near the human being. A mechanical means moves the magnet away from its normal position or back to such position. The blood flow induced signals, which are pulsatile, are sensed by electrodes placed on the skin adjacent to the artery. Mixed with the blood flow signals are the local electrocardiogram signals. In addition, the electrodes also pick up random noises which are not synchronized with the heart. The signals are amplified and processsed by a repetitive waveform averager which is synchronized by a cardiogram signal obtained from auxiliary electrodes. The waveform averager accumulates a first predetermined number of composite pulsatile signals from said measuring electrodes during a first series of heart cycles occurring when the magnetic field is produced in the region of the artery, and accumulates an equal number of composite pulsatile signals from said measuring electrodes during a second series of heart cycles occurring when the magnetic field in the region is suppressed. A signal selector includes a comparator connected at the input of the waveform averager for comparing each incoming pulsatile signal with predetermined acceptable signal characteristics, so that the incoming pulsatile signal will be accumulated by the waveform averager only if it is accepted by the signal selector. The waveforms registered in the waveform averager respectively during the first and the second series of heart cycles are subtracted from each other to obtain the blood flow pulse substantially free from electrocardiogram and random noise influence.</p> |
