Smith D C, Tan S, Follett D H
Department of Anaesthesia, Western Infirmary, Glasgow, UK.
J Med Eng Technol. 1992 Sep-Oct;16(5):210-3. doi: 10.3109/03091909209021985.
Skin-electrode impedance was determined between two disposable electrodes 5 cm apart on the volar skin of the forearm in 20 patients during cooling on cardiopulmonary bypass. Measurements were made using a constant direct current pulse of 200 microseconds duration, at a current density of 25.6 mA cm-2. The mean inter-electrode resistance was 1.11 k omega, and the mean inter-electrode capacitance was 33.3 nF. In 19 patients there was no change in the inter-electrode resistance or the inter-electrode capacitance with changes in skin temperature from 27.5 to 36.0 degrees C. In one patient the inter-electrode resistance increased from 1.71 k omega at 35 degrees C to 1.94 k omega at 31.0 degrees C, while the inter-electrode capacitance increased from 19.6 to 26.6 nF. We conclude that temperature effects on the impedance of the stimulus electrodes are not responsible for the observed failure of evoked electromyography during clinical monitoring of neuromuscular function.
在20例接受体外循环降温的患者中，在前臂掌侧皮肤相距5 cm的两个一次性电极之间测定皮肤-电极阻抗。测量使用持续时间为200微秒的恒定直流脉冲，电流密度为25.6 mA/cm²。电极间平均电阻为1.11 kΩ，电极间平均电容为33.3 nF。19例患者的电极间电阻和电极间电容在皮肤温度从27.5℃变化到36.0℃时未发生改变。1例患者的电极间电阻从35℃时的1.71 kΩ增加到31.0℃时的1.94 kΩ，而电极间电容从19.6 nF增加到26.6 nF。我们得出结论，在神经肌肉功能的临床监测中，温度对刺激电极阻抗的影响并非导致观察到的诱发肌电图失败的原因。
