Development of Sympathetic Nerve Activity Quantitative Analysis System in Anesthesia and Intensive Care Area

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We have developed the system which could measure muscle sympathetic nerve activity (MSNA) and could quantify the activity level of them. The system used the electro-magnetic shielding and isolated differential preamplifiers for discriminating electrical burst potential in the nerve from the environmental noise in surgical rooms or in the intensive care rooms. By using this quantitative measurement system, we have found the clinical findings : 1) Effects of stellate ganglion block on tibial nerve muscle sympathetic activity. 2) Effects of positive and negative pressure breathing on muscle sympathetic nerve activity. Stellate ganglion block increases heart rate and systemic blood pressure, and the reason is estimated as the block of afferent flux of vagal nerve activity from the baroreceptor on the aortic arch. We have found that the left stellate ganglion block increased efferent MSNA on tibial nerve because of the efferent muscle sympathetic nerve activity (MSNA) is affected by the baroreceptor response. Increasing levels of continuous positive pressure breathing (CPPB) at 5,10, and 15 mmHg produced increasing levels of MSNA,however, during continuos negative pressure breathing (CNPB), MSNA was virtually constant. Mean blood pressure decreased and heart rate increased during CNPB,while neither factor changed significantly during CPPB.CVP increased during CPPB and decreased during CNPB.These results suggest that CPPB and CNPB do not have the inverse effects on MSNA.