[The function of the sympathetic nervous system and its behavior during regional anesthesia].

The activity of the sympathetic nervous system is of fundamental importance in the regulation of vital bodily functions. Impairment of sympathetic neuronal efferences results in considerably disordered effector function, and in some cases even in complete failure. Clinically, this is of great significance, because if an anesthetic agent produces cause the sympathetic system to block, the effects can be serious in individual cases, particularly on the cardiovascular system. If complications are to be avoided, it is essential to assess the degree of block correctly. Clinical monitoring has a variety of applications, a particularly useful one being measurement of the sympathetic system during regional anesthesia, for which quantification of the blocking effect is a clinical necessity and the degree of block needs to be ascertained without delay, for example in the case of spinal or peridural anesthesia. The activity of the sympathetic system can be monitored indirectly by two means: by measuring changes in skin temperature (with reference to all circulatory parameters), as these reflect its influence on the arterioles, and by measuring the skin resistance caused by the eccrinal sweat glands, which are also regulated by the sympathetic system. As the anatomical and functional structure of the system is highly complex a connection between the two measurements cannot necessarily be assumed. The two variables were measured simultaneously during spinal anesthesia and analysed. It was shown that the two measurements correlated well, at least in the statistical middle range, and that skin resistance was by far the faster and more sensitive of the two.