• Tadeusz Musialowicz, Markku Hynynen, Heidi Yppärilä, Pekka Pölönen, Esko Ruokonen, and Stephan M Jakob.
• Critical Care Research Program, Division of Intensive Care, Department of Anaesthesiology and Intensive Care Medicine, Kuopio University Hospital, Kuopio, Finland.
• J. Cardiothorac. Vasc. Anesth. 2004 Oct 1; 18 (5): 559-62.

ObjectivesMidlatency auditory-evoked potentials (MLAEPs) may provide an objective measure of depth of sedation. The aim of this study was to evaluate MLAEPs for measuring sedation in cardiac surgery patients.DesignProspective study.SettingIntensive care unit of a university hospital.ParticipantsTwenty-two patients scheduled for elective coronary artery bypass grafting.InterventionsMLAEPs were obtained at 5 time points: the day before surgery (baseline), 1 hour before surgery, after premedication, postoperatively during deep (Ramsay 6) and moderate (Ramsay 4) sedation, and the day after surgery.Measurements And Main ResultsThe latency of the Nb MLAEP component increased from 44 ms (38-60 ms; median, range) at baseline to 49 ms (41-64 ms) after premedication (p = 0.03) and further to 63 ms (48-80 ms) during deep sedation after surgery (P < 0.01). Although a decreasing clinical level of sedation after rewarming was not associated with a significant change in Nb latency (61 ms [42-78 ms]), the MLAEP NaPa amplitude increased from 0.9 muV (0.4-1.6 microV) to 1.3 muV (0.8-3.9 microV; p = 0.01). Nb latency remained increased the day after surgery (49 ms [37-71 ms]) as compared with baseline (p < 0.01).ConclusionsMLAEP latencies can reflect subtle changes in auditory perception, while amplitudes seem to change with transition between deep levels of sedation.

32 keywords...

hide…