Monitoring of sedation with BIS Index, comparison with Ramsay and Cook sedation scores

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Introduction

Sedation and analgosedation are an integral part of intensive care medicine. The level of sedation is often very important for the final result of the treatment. Different sedation scores are used to asses this level (Ramsey, Cook, etc.). But these scores can be very subjective, dependent on a observer and can show quite great interindividual differences. The Bispectral index (BIS) is a processed EEG parameter and shows continuously the level of inhibition of brain function during application of drugs for anesthesia and sedation.

We have tried to find if there is any relation between the value of the BIS index and the Ramsay or Cook score. In the case of a positive result, there can be a chance of exact titration of drugs and possible economical profit.

Methods

The group of 20 patients hospitalized in our ICU (October 1998-September 1999). Including criteria-GCS 15 and the need of continual sedation or analgosedation. Monitoring of all patients by the monitor `Aspect A-1000 TM'. The values of the BIS index were recorded to protocol at any time of change in the level of sedation. At the same time this level of sedation was evaluated by two physicians (to prevent interindividual differences) by the use of Ramsay and Cook scores. All 75 examinations were recorded to study protocol. Results were assessed by help of means (median) + SD (range) and graphs.

Results

See Figs 1 and 2.

Conclusion

Figures 1 and 2 demonstrate that a narrow span of BIS index values includes a very wide scale of a depth of sedation and analgosedation assessed by Ramsay and Cook scores. These results and especially our experiences with continual monitoring show that to rely only on BIS index or to titrate drugs according to these values is impossible. We admit that bigger number of patients is needed for better evaluation.

Figure 1

Figure 2