Changes in Skin Conductance Measurement as an Endpoint Monitor for Sympathetic Blocks

This study is intended to evaluate a monitor that will facilitate ascertainment of an effective sympathetic blockade following Lumbar Sympathetic blocks. Utilization of a monitor with a rapid response and easy clinical applicability which can demonstrate effective sympathetic block would increase efficiency within the procedure suite and also serve to function as an objective endpoint for the evaluation of sympathetic blockade in future research.In current clinical practice, the most commonly used monitoring methods are clinical observations of sympathetic blockade, skin temperature monitoring, pulse pressure monitoring and any combination of these monitoring methods. The skin temperature and pulse pressure may increase after sympathetic block. However, changes in the skin temperature and pulse pressure often demonstrate an unpredictable or delayed response. Confounding variables, such as ambient temperature, coexisting vascular disease, use of other vasoactive medications may contribute to inconsistencies in the temperature or pulse pressure responses. Normal sympathetic activity stimulates muscarinic receptors in the periphery that subsequently stimulate the sweat glands to secrete and fill with sweat containing sodium and other electrolytes. The electrolytes present in the sweat increase the electrical conductance while decreasing the electrical resistance at the skin level. The real-time changes in skin conductance indices can be monitored at the skin level, by use of non-invasive electrodes attached to the skin (similar to EKG electrodes). A computer program analyzes the data and produces a real-time graphic and numeric data demonstrating the skin conductance response. The initiation of successful sympathetic blockade can cause rapid cessation of the skin sympathetic activity that leads to a decrease in skin conductance within seconds.