This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Haenggi, M. Articles by Jakob, S. M. Search for Related Content PubMed PubMed Citation Articles by Haenggi, M. Articles by Jakob, S. M. Related Collections Critical Care Anesthetic Techniques Monitoring (Non-cardiac)

---

TECHNOLOGY, COMPUTING, AND SIMULATION

Measuring Depth of Sedation with Auditory Evoked Potentials During Controlled Infusion of Propofol and Remifentanil in Healthy Volunteers

Matthias Haenggi, MD^*, Heidi Ypparila, Ph Lic, Jukka Takala, MD, PhD^*, Ilkka Korhonen, PhD, Martin Luginbühl, MD, Steen Petersen-Felix, MD, PhD, and Stephan M. Jakob, MD, PhD^*

Departments of *Intensive Care Medicine and Anesthesia, University Hospital Bern, Bern, Switzerland Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland, VTT Information Technology, Tampere, Finland

Address correspondence to Stephan M. Jakob, MD, PhD, Department of Intensive Care Medicine, University Hospital Bern (Inselspital) CH-3010 Bern, Switzerland. Address email to stephan.jakob{at}insel.ch

Avoiding excessively deep levels of sedation is a major problem in intensive care patients. We studied whether clinically relevant levels of sedation can be objectively assessed using long latency auditory evoked potentials. We measured the auditory evoked potentials at 100 ms after the stimulus (N100) in 10 healthy volunteers during stepwise increasing, clinically relevant levels of sedation (Ramsay score [RS] 2–4). The volunteers were studied on three separate occasions and received an infusion of either propofol or a combination of propofol and remifentanil. Effects of remifentanil infusion alone were tested during target controlled infusion (target plasma concentrations: 1, 2, and 3 ng/mL). Remifentanil did not affect evoked potential amplitudes and latencies. During both propofol-induced and propofol/remifentanil-induced sedation, the N100 amplitude decreased similarly without an effect on the latencies as the level of sedation increased from Ramsay score 2 to Ramsay score 4 (P < 0.01). At the same clinical level of sedation, propofol plasma concentrations were larger when sedation was achieved by propofol alone (propofol versus propofol/remifentanil, RS 3: 2.12 µg/mL ± 0.51 versus 1.32 ± 0.43, P < 0.01; RS 4: 3.37 ± 0.47 versus 1.86 ± 0.34, P < 0.01). Our results suggest that long latency auditory evoked potentials provide an objective electrophysiological analog to the clinical assessment of sedation independent of the sedation regime used.

IMPLICATIONS: Acoustic stimuli induce distinct changes in the electroencephalogram (EEG). We found that one component of these EEG modifications can be used to monitor the targeted light levels of sedation in critically ill patients nearly continuously, independent of adding remifentanil to a propofol-based sedation regime.

This article has been cited by other articles:

				M. Haenggi, H. Ypparila-Wolters, S. Buerki, R. Schlauri, I. Korhonen, J. Takala, and S. M. Jakob Auditory Event-Related Potentials, Bispectral Index, and Entropy for the Discrimination of Different Levels of Sedation in Intensive Care Unit Patients Anesth. Analg., September 1, 2009; 109(3): 807 - 816. [Abstract] [Full Text] [PDF]

				A. Lamas, J. Lopez-Herce, L. Sancho, S. Mencia, A. Carrillo, M. J. Santiago, and V. Martinez Bispectral Index and Middle Latency Auditory Evoked Potentials in Children Younger Than Two-Years-Old Anesth. Analg., February 1, 2008; 106(2): 426 - 432. [Abstract] [Full Text] [PDF]

				D. Hohener, S. Blumenthal, and A. Borgeat Sedation and regional anaesthesia in the adult patient Br. J. Anaesth., January 1, 2008; 100(1): 8 - 16. [Abstract] [Full Text] [PDF]

				M. Haenggi, H. Ypparila, K. Hauser, C. Caviezel, I. Korhonen, J. Takala, and S. M. Jakob The Effects of Dexmedetomidine/Remifentanil and Midazolam/Remifentanil on Auditory-Evoked Potentials and Electroencephalogram at Light-to-Moderate Sedation Levels in Healthy Subjects Anesth. Analg., November 1, 2006; 103(5): 1163 - 1169. [Abstract] [Full Text] [PDF]