New parameters of skin conductance compared with bispectral index® monitoring to assess emergence from total intravenous anaesthesia

Background. Arousal after total i.v. anaesthesia (TIVA) has been reported to be detectable by monitoring the number of fluctuations per second (NFSC), a parameter of skin conductance (SC). However, compared with monitoring of the bispectral index (BIS (R)), the predictive probability of NFSC was significantly lower. The aim of this study was to determine the value of the two new, not yet published parameters of SC, area under the curve (AUC) methods A and B, for monitoring emergence from TIVA compared with monitoring of NFSC and BIS (R). Methods. Twenty-five patients undergoing surgery were investigated. NFSC, AUC A, AUC B, BIS (R), and haemodynamic parameters (mean arterial pressure and heart rate) were recorded simultaneously. The performance of the monitoring devices in distinguishing between the clinical states 'steady-state anaesthesia', 'first clinical reaction', and 'extubation' were compared using the method of prediction probability (Pk) calculation. Results. 1360 showed the best performance in distinguishing between 'steady-state anaesthesia' vs 'first reaction' (Pk BIS (R) 0.95; NFSC 0.73; AUC A 0.54; AUC B 0.62) and 'steady-state anaesthesia' vs 'extubation' (Pk BIS (R) 0.99; NFSC 0.73; AUC A 0.71; AUC B 0.67). However, the time from first BlS((R))> 60/SC > 0 to a first clinical reaction was significantly shorter for BIS (R) (median BIS (R) 180 s; NFSC 780 s; AUC A 750 s; AUC B 690 s; P < 0.001). Conclusions. AUC A and AUC B did not improve accuracy of SC monitoring in patients waking after TIVA.