The Effect of Different Stages of Neuromuscular Block on the Bispectral Index and the Bispectral Index-XP Under Remifentanil/Propofol Anesthesia

Abstract

Facial electromyographic activity and neuromuscular block could influence bispectral index (BIS) depth of anesthesia monitoring. In this study we examined, in 30 patients undergoing general surgical procedures, the effect of different stages of neuromuscular block on BIS monitoring and compared the conventional A-2000 BIS trade mark (BIS(3.4)) with the new BIS-XP trade mark (BIS(XP)). At deep surgical anesthesia BIS(3.4) of approximately 40, under a propofol 3.61 microg/mL target-controlled infusion and a 0.15-0.3 microg. kg(-1). min(-1) remifentanil infusion, mivacurium 0.15 mg/kg was administered. The onset of neuromuscular block triggered a brief transient odd divergence in response that manifested as a BIS(3.4) increase from 43 +/- 4 to 49 +/- 7 (P = 0.007) and a BIS(XP) decline from 41 +/- 3 to 35 +/- 3 (P = 0.003) at 1 +/- 0.2 min. Then, 2.5 +/- 1 min after mivacurium administration, both monitors returned to baseline values of 43 +/- 5 and 40 +/- 4, respectively. After that, BIS(3.4) and BIS(XP) did not significantly change during complete neuromuscular block or during various levels of neuromuscular recovery. At all phases, BIS(XP) was significantly lower than BIS(3.4). Our study indicated that the BIS(3.4)/BIS(XP) bias and the wide limits of agreement do not allow values given by the two monitors to be used interchangeably.

Cerebral state monitor, a new small handheld EEG monitor for determining depth of anaesthesia

“…Two recent studies comparing BIS with entropy calculated from the Datex monitor show results very much in line with ours [19,20]. Even a comparison of two different versions of BIS has shown that an index value from one version may not entirely correspond to an index derived from another [23]. Attempts to explain these discrepancies between indices are only speculative.…”

Bispectral index correlates well with Richmond agitation sedation scale in mechanically ventilated critically ill patients

“…It could be possible that the fentanyl infusion provided potent analgesia and therefore there was less EMG interference in our patients [17]. In fact, BIS changes accompanying neuromuscular blockade have raised issues about the adequacy of sedation and analgesia administered to ICU patients [18].…”

Monitoring the anaesthetic depth in children – an update

“…The major concern is that EMG signal can be abolished with neuromuscular blocking agents and the loss of his high-frequency signal may be interpreted as an increase in anaesthesia depth; neuromuscular blockers giving a false impression of deepening anaesthesia. There is now ample evidence that this is a real phenomenon [81][82][83][84][85]. There is no reason to think this issue would not be relevant to paediatric anaesthesia.…”