| 摘要 |
<p>patient's own heart is used as a voltage source for measurement of the impedance Z<Sub>E</Sub> between two EKG electrodes (10, 11) attached to his body (12). A test impedance Z<Sub>T</Sub> and a normally open switch (22) are connected in parallel with the electrodes (10, 11). The voltage signals at these electrodes (10, 11) are conveyed to a differential amplifier (18) which presents an EKG waveform to a strip chart recorder (20). The amplitude A<Sub>L</Sub> of an EKG signal obtained while the EKG electrodes (10, 11) are shorted (switch closed) is compared to the amplitude A<Sub>u</Sub> of an EKG signal obtained after removal of the impedance short (switch open). The value of the inter-electrode impedance Z<Sub>E</Sub> is then</p><p>The value of the shorting impedance ZT is made equal to the maximum permitted inter-electrode impedance. If the amplitude of the EKG signal taken from a patient decreases upon temporary insertion of the impedance short to a value AL less than half of the EKG amplitude Au obtained without the impedance short, the inter-electrode impedance ZE is too high.</p> |
