Comparison of auditory evoked potential index, bispectral index and spectral edge frequency for monitoring depth of anesthesia during emergence from anesthesia / 中华麻醉学杂志

ABSTRACT

Objective Auditory evoked potential index (AAI) has been proposed for monitoring anesthetic depth. The aim of this study was to compare tins new technique with hispectral index (BIS) and 95% spectral edge frequency (SKF) for assessing anesthetic depth during emergency from propofol-isoflurane anesthesia. The ability of these techniques in distinguishing consciousness from unconsciousness was also evaluated. Methods Thirty six ASA I - II patients ( 15 male, 21 female) undergoing elective surgery under propofol-isoflurane anesthesia were enrolled in the study. Age ranged from 18 to 75 years and body weight from 35 to 80 kg. Patients with psychoneural diseases or hearing disturbances were excluded. The patients were premedicaled with phenobarbitai sodium 0.1g and airopine 0.5mg. Anesthesia was induced with rnidazolam 0 .05-0.1 mg.kg1,fentanyl 5- 10ug.kg1 and vecuronium 0. 1-0.2mg.kg-1 and maintained with propofol infusion (8-16ml. h 1) and isoflurane inhalation (0.5% -1.0%). Intermittent IV boluses of vecuroniuni were given when needed. The patients were transported to recovery room after surgery. AAI, HIS, SKF and hemodynamic parameters were monitored and recorded on entering the recovery room, before extubation, during extubalion, 5, 10, 20 min after exlubation and before release from recovery room. Results AAI, BIS and SEF were 40.9?11.7,73.64?10.8 and 17.5?2.8 respectively on entering recovery room and increased to 72.6 ?11.0, 88.2?7.3 and 22.5?2.6 during exlubation. The increase in AAI was significantly greater. The mean values of AAI before and after responding to light glabellar tap or loud auditory stimulus were 36. 1?11.5 and 52.4?12.3 respectively, the mean values of BIS were 71.9?11.5 and 78 . 6?11.9 and of SKF 16.7?3.0 and 18. 6?3.2 .Only AAI demonstrated a significant difference detween consciousness and unconsciousness. Conclusion AAI, HIS and SKF all increase gradually during emergence from anesthesia. AAI is most sensitive among the three techniques and is most useful in detecting the transition from unconsciousness to consciousness.