局所麻酔薬各種投与法における聴性脳幹反応の研究

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抄録

The effects of total spinal anesthesia (TSA), subarachnoidal block (SAB) and i. v. lidocaine treatment (ILT) on auditory brain stem responses (ABRs) were studied by time-course recording in 28 cases. A dose (20ml) of 1.5% mepivacaine hydrochloride was injected into the subarachnoidal space at the Th₁-Th₂ level for TSA and at the L₄-L₅ level for SAB, respectively, and 2 or 3ml of 2% lidocaine hydrochloride, i. v. for ILT. On application of TSA, the 2nd to 5th or 1st to 5th waves in ABR disappeared for about 2hr reversibly in most cases. Changes in blood pressure and pulse rate seemed not to affect ABRs during TSA. Mepivacaine injected into the subarachnoidal space presumably exerted direct effects on the brain stem. The depression of awareness during TSA appeared to be caused by direct anesthesia of the brain-stem reticular formation. The direct effects of mepivacaine on the brain stem were also ascertained by the changes of the pupillary diameter and prolongation of interwave latency (1st to 5th) during TSA. Neither SAB nor ILT affected ABRs.