Clinically relevant asymmetry of bispectral index during recovery from anaesthesia for ear-nose-throat surgery in adults and children

Abstract

SummaryThis study investigates the incidence of clinically relevant asymmetry in bispectral index readings from different sides of the skull (using two monitors) during ear-nose-throat surgery in 42 adults and 46 children. A unilateral increase or decrease > 10% from baseline was defined as an 'asymmetry'. Asymmetry followed by movement after stimulation was defined as a 'clinically relevant asymmetry'. Asymmetry occurred in 39 out of 42 adults (93%) and in 20 out of 46 children (44%) during surgery and in 24 out of 42 adults (57%) and in 17 out of 46 children (37%) during recovery. Clinically relevant asymmetry was observed in 5 out of 42 adults (12%) and 6 out of 46 children (13%). The incidence of asymmetry was higher in adults during surgery (p = 0.0002). In conclusion, clinically relevant bispectral index asymmetry has been observed in > 10% of paediatric and adult anaesthesia and may have clinical implications.

Asymmetry of the bispectral index in lateral decubitus position during one-lung ventilation: A prospective-observational study

“…[7,9, 10] Also, intraoperative asymmetry of the two sides was introduced in several studies. [5,11] Fudickar et al reported that BIS asymmetry occurred in 12% of adults during ear-nose surgery [5] and found that asymmetry was not related to the side position during surgery. This percentage was higher than that in our study (8.9%) and might be associated with unanticipated stimulation or movement during ear-nose surgery.…”

“…Since 'electrode one' of the BIS sensor was placed on the centre of the forehead, the left and right 'electrode one' were randomly placed above and below each other for each set of data collection. [5,7] Two BIS sensors were attached to two Aspect XP BIS monitors (Aspect Medical System, software version 3.2, Model A-2000, Natick, MA, USA). The BIS monitors were using two monitors, changing the actual monitors to avoid device bias switched sequentially to avoid any monitoring site and machine bias.…”

“…Also, BIS asymmetry readings have been reported as different values in left-and the right-sided BIS recordings. [5,6] This study was performed to investigate the incidence and possible clinical relevance of lateral differences of BIS during lateral decubitus positioning and one-lung ventilation.…”

A history of pediatric anesthesia: a tale of pioneers and equipment

“…The dream of Robert M. Smith to have a ‘monitor of consciousness’ (49) has been at least partially fulfilled with the introduction of processed electroencephalogram. Unfortunately, these values have never been validated in children, and significant problems include differing numbers with varying agents at equal minimum alveolar concentration (MAC) (50), differences for the right and left side of the brain (51,52), higher values in children than in adults at equi‐MAC concentrations (53,54), and increases in score when sevoflurane concentrations exceed 3% (55). Although the data in adults are reasonable, the use of BIS (Aspect Medical now Covidien, Mansfield, MA, USA) and SedLine (Masimo, Inc., Irvine, CA, USA) monitors in children remains questionable, particularly for infants and neonates.…”

The bilateral bispectral and the composite variability indexes during anesthesia for unilateral surgical procedure

“…[ 6 7 ] Differences in BIS indexes were detected in shunting patients for carotid surgery,[ 8 ] either in the presence of unilateral brain lesions[ 9 ] or during the anesthesia process. [ 10 11 ]…”