Comparison of the CSM and BIS Monitors in Healthy Volunteers during Propofol Induction

L. Castilla, MD**; Dra. Tania Troncos  M**; G. Núñez, MD, PhD*; A. Recart, MD*; P. Sepúlveda. MD*;

*Clínica Alemana -Universidad del Desarrollo Santiago de Chile

**  Hospital Nac. Arzobispo Loaiza Lima, Perú.

Introduction

The Cerebral State Monitor (CSM) has been recently introduced into clinical practice as a monitor for assessing level of consciousness during anesthesia. The CSM delivers the CSI index, using the fuzzy logic approach for the EEG analysis. Similar to bispectral index (BIS), the CSI values range from 0 to 100 according to the depth of hypnosis. This observational study was designed to compare the CSM with the BIS during propofol induction of anesthesia, as well as to correlate both values with the clinical level of sedation and the estimated plasmatic concentration (Ce) of propofol.

Mehods:

After Institutional approval, 15 healthy unpremedicated volunteers were enrolled. Both the CSM and BIS monitors were connected to all patients before starting an effect compartment controlled infusion of propofol (Diprifusor: Marsh kinetics ke0 0,26 min-1). Propofol was targeted at 0,5 ug/ml and increased with 0.5 ug/ml until lose of eye reflex (LER). At every step, once plasmatic- effect pseudoequilibrium was reached, one of the investigators registered the CSM and BIS values together with the Ce of propofol and the Ramsay sedation scale.  Once the volunteer lost the eye reflex, a 5 Hz-5sec tetanic stimuli was administered. Motor and EEG response were evaluated. After that, propofol infusion was reduced step by step (0,5 ug/ml) and awakening Concentration were registered, together with the corresponding EEG  parameters.

Statistics:

for all measures median (range)

Results:

At Ramsay sedation scale of 3, at Ce of 1,5 ug/ml, CSM de 84 ±10 and BIS was 77±7,5. Once LES, (Ramsay 4),  Ce was 2,5±0,5 ug/ml, CSM 64 ± 8, and BIS 65±7. At awakening, Ce was 2,05±0,3 ug/ml, CSM 84 ± 13 and BIS 76 ± 14.

All volunteers presented motor response after pain stimulation, none of them had changes to the EEG parameter.

Conclusion:

These preliminary results suggest the CSM performs similarly to BIS well with BIS values, and may become an alternative for use in daily clinical practice. Interestingly none of the monitors responded to the painful stimuli

References

1.             Struys, M. et al.; Anesthesiology 2003:802-12.

2.             Recart A. et al;   Anesth Analg. 2003:1667-74.