Measurement of the Skin Sympathetic Nerve Activity

Sympathetic nerve activity can be measured transcutaneously in awake patients by computer-based filtering of raw signal obtained via skin leads attached on the chest. Electrocardiogram can be removed by applying a high-pass filter setting of 150 Hz. Electromyogram can be filtered by applying a high-pass filter setting of 500 Hz or a band-pass filter setting of 500-1000 Hz. However, it is not known whether the skin sympathetic nerve activity (SKNA) can be measured in anesthetized and/or paralyzed patients. Therefore, we planned this pilot study to observe whether the SKNA can be obtained in these patients. If the SKNA ca be observed, it will be presented in milivolt (uV).