Comparison of five sedation scoring systems by means of auditory evoked potentials

Objective: To review five sedation scoring systems and to determine their c orrelation with an objective method for assessing the level of sedation by means of auditory evoked potentials (AEP) in critically ill patients. Design: Prospective clinical study. Setting: Multidisciplinary intensive care unit in a university hospital. Patients: Ninety-five consecutive patients requiring sedation during intens ive care therapy. Measurements and results: Previous studies have shown that auditory evoked potentials, especially latencies of the midlatency component N-b,N- could s erve as an indicator of depth of anaesthesia. In the present study we used this electrophysiological method to evaluate sedation during intensive care therapy. Changes in latency of peak N-b were compared with various levels of sedation assessed by five established sedation scoring systems. As in an aesthesia, latencies of N-b increased with increasing depth of sedation. Am ong the scoring systems, the one developed by Ramsay correlated best with c hanges in N-b latency (r(2) = 0.68). The coefficient of determination r(2), Of the other scores ranged from 0.56 to 0.61. Conclusion: For the assessment of sedation, several scoring systems have be en introduced into clinical practice: but the differentiation of deeper sed ation levels, especially remains poor. In this study we compared auditory e voked potentials, as an objective method with which to assess the level of sedation, with five different sedation scoring systems. In comparison with changes in latency of the midlatency component N-b, Ramsay's sedation score showed the closest correlation. Objective electrophysiological monitoring is desirable during long-term sedation.