전신-경막외 병용 마취 시 Bispectal Index System을 이용한 Isoflurance의 최소 호기말 농도 측정

Abstract

One of the benefits of combined general-epidural anesthesia (CGEA) is the capability reducing the inhalational agent concentration. We evaluated the minimal end-tidal isoflurane concentration during CGEA by using Bispectral Index System (BIS). Twenty patients undergoing total hip arthroplasty were randomly selected. After general anesthesia with isoflurane and pure oxygen, 2.0% mepivacaine was injected through epidural catheter. Subsequently, end-tidal isoflurane concentration was reduced from 1.0 to 0.8, 0.6 and 0.5 vol% at 10 minutes intervals, and BIS scores were checked at each isoqlurane concentration. The BIS score below 50 is considered to be an optimal level for sedation and hypnosis. The result showed that the BIS scores of 1.0, 0.8, 0.6 and 0.5 vol% of end-tidal isoflurane concentration were 43.9 ± 7.6, 44.8 ± 7.0, 45.8 ± 6.0 and 50.3 ± 6.7, respectively. Therefore we conclude that the minimal end-tidal isoflurane concentration for CGEA with pure oxygen was 0.6 vol%.