Auditory evoked potential index does not correlate with observer assessment of alertness and sedation score during 0.5% bupivacaine spinal anesthesia with nitrous oxide sedation alone

作者：Ichikawa Junko^*; Taira Kumiko; Nishiyama Keiko; Endo Masato; Kodaka Mitsuharu; Kawamata Miwako; Komori Makiko; Ozaki Makoto

来源：Journal of Anesthesia, 2012, 26(3): 400-404.

DOI：10.1007/s00540-011-1316-z

• Auditory evoked potential index
• Observer assessment of alertness and sedation score
• Nitrous oxide

The aim of this study was to evaluate the auditory evoked potential (AEP) index as a hypnosis monitor during nitrous oxide (N2O) sedation added to spinal analgesia. %26lt;br%26gt;Forty-five patients scheduled to undergo surgery under spinal anesthesia were recruited after giving informed consent. Adequate anesthesia levels were confirmed, and a disposable AEP index sensor (aepEX, Medical Device Management) was placed. A tight facemask was fitted, and a fresh gas flow of 100% oxygen 10 L/min was provided. AEP index monitoring was then initiated, and measurements and observer assessment of alertness/sedation (OAA/S) scores were recorded manually. N2O was administered in stepwise increases in the end-tidal concentration of 33%, 50%, and 67%. Paired AEP index and OAA/S scores were obtained immediately before each change in N2O concentration. %26lt;br%26gt;Sixteen patients were excluded from final analysis because of nausea, vomiting, or abnormal excitatory behaviors. The increases in N2O concentration induced significant decreases in OAA/S scores and no substantial AEP index changes. Although OAA/S scores of 1 and 2 were observed in only two and five patients, respectively, a reduction in the OAA/S score from 5 to 1 was associated with a significant decrease in AEP index to the level indicative of moderate sedation. %26lt;br%26gt;The AEP index might not be a suitable indicator of light hypnosis as defined by an OAA/S score of a parts per thousand yen3 during sedation with N2O alone.

• 出版日期2012-6