[The monitoring of sympathetic activity following stellate ganglion block].

Abstract

Variations in skin resistance are an indicator of a patient's sympathetic nerve activity. To record these variations, a mobile measuring system was developed. Even if this method is not yet used as a clinical routine, it could be helpful in studying the effects of nerve blocks in anesthesia. It seems to be advantageous for estimating the effectiveness of a block, the stress of the patient, and for recognizing very early reactions of a patient's sympathetic system. METHOD. An objective sign of a successful and sufficient block should be diminishing and finally the total lack of skin reaction amplitudes if the block is total. This was measured in a patient (male, 30 years old, nonsmoker, calm type) who suffered from a sudden loss of hearing on the left for four consecutive days when his left stellate ganglion was blocked. The effectiveness of the block was estimated from a two-channel measurement of skin reactions. On one channel the skin resistance of the blocked left side was recorded and on the other, unblocked skin areas of the right side were measured simultaneously. RESULTS. Although all four blocks were successful, which was evidenced by a Horner syndrome as well as elevated skin temperature 1-2 min after the injection of 7 ml bupivacaine (C6/C7), in all four cases residual sympathetic activity could be measured. In Fig. 1, the diminishing amplitudes of channel A as compared with channel B demonstrate this finding after the onset of a block at 2:03 p.m. An interpretation of skin reactions generated by a series of action potentials is given.(ABSTRACT TRUNCATED AT 250 WORDS)