Skin conductance monitoring compared with bispectral index monitoring to assess emergence from general anaesthesia using sevoflurane and remifentanil

Background. Changes in skin conductance have previously beenreported to correlate well with plasma levels of stress hormonesand awakening stimuli. In this study, monitoring of skin conductanceduring emergence from general anaesthesia was compared withthe monitoring of bispectral index (BIS). Methods. Twenty-five patients undergoing minor elective surgerywere investigated. The number of fluctuations in mean skin conductance(NFSC), BIS and haemodynamic parameters were recorded simultaneously.The performance of the monitoring devices to predict and distinguishbetween the clinical states ‘steady-state anaesthesia’,‘first reaction’ and ‘extubation’ werecompared using the method of prediction probability (P_K) calculation. Results. Both monitors showed similar performance in distinguishingbetween ‘steady-state anaesthesia’ vs ‘firstreaction’ (P_K NFSC 0.89; BIS^® 0.94) and ‘steady-stateanaesthesia’ vs ‘extubation’ (P_K NFSC 0.96;BIS^® 0.96). The response times of the monitors, to indicatethe likelihood of ‘first reaction’, were not significantlydifferent. Conclusions. NFSC, as a parameter of skin conductance, performedsimilarly to BIS in patients waking after a general anaesthetic.