Share this article on:

Performance of AEP Monitor/2-derived composite index as an indicator for depth of sedation with midazolam and alfentanil during gastrointestinal endoscopy

Huang, Y.-Y.*,†; Chu, Y.-C.*; Chang, K.-Y.*; Wang, Y.-C.; Chan, K.-H.*; Tsou, M.-Y.*

European Journal of Anaesthesiology (EJA): March 2007 - Volume 24 - Issue 3 - p 252-257
doi: 10.1017/S0265021506001633
Original Article

Background and objective: The A-Line® auditory evoked potential index (AAI) (AEP Monitor/2, Danmeter A/S, Odense, Denmark) is a newly developed composite parameter representing the degree of hypnosis. We conducted a prospective, observational study to explore the performance and validity of the AAI during conventional sedation for gastrointestinal (GI) endoscopy.

Methods: Thirty adults of either sex, age <65, scheduled for combined oesophagogastroduodenoscopy (OGD) and colonoscopy under sedation with intravenous (i.v.) midazolam and alfentanil were enrolled. The sedative end-point was set at the Observer’s Assessment of Alertness/Sedation (OAA/S) score less than 4. An AEP Monitor/2 was used in all patients. AAI, sedation scores, heart rate (HR), blood pressure (BP) and SPO2 were recorded every 2 min up to the end of the procedure. Receiver operator characteristic analysis was used to test validity and to select optimal sedation.

Results: There was a significantly positive correlation between AAI and OAA/S scores (ρ = 0.886; P < 0.001). The AAI also showed significant differences between subsequent levels of sedation scores (P < 0.001). AAI greater than 54 indicated fully awake or minimal sedation and values between 54 and 42 were suggestive of moderate sedation. Values between 42 and 34 were associated with moderate to deep sedation and readings below 34 were associated with deep sedation. The relative risk of SPO2 < 95% for OAA/S = 2 compared with 3 was 15.98 (95% confidence interval (CI): 3.94–64.81).

Conclusions: AAI is an effective tool for monitoring sedation during GI endoscopy induced by i.v. midazolam and alfentanil.

National Yang-Ming University, Taipei Veterans General Hospital & School of Medicine, *Department of Anaesthesiology, Taipei, Taiwan, ROC

Institute of Clinical Medicine, Taipei, Taiwan, ROC

Division of Healthcare and Service, Department of Medicine, Taipei, Taiwan, ROC

Correspondence to: Mei-Yung Tsou, Department of Anaesthesiology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Rd, Taipei 112, Taiwan, R.O.C. E-mail:; Tel: +886 2 2875 7636; Fax: +886 2 2874 9775

Accepted for publication 01 September 2006

© 2007 European Society of Anaesthesiology