Simultaneous Anesthetic Depth Monitoring Using Noxious Stimulation Response Index and Bispectral Index: A Preliminary Report of a Prospective Observational Study in Clinical Settings

type:TOHO University Scholarly Publication
Original Article
Introduction: Anesthetic depth monitors, such as the bispectral index (BIS) monitor, are based on the analyses of electroencephalogram. SmartPilot View, another type of anesthetic depth monitor, calculates the effect-site concentration of anesthetics based on pharmacokinetic/pharmacodynamic simulations, computes the pharmacodynamic interaction between hypnotics and opioids, and displays the noxious stimulation response index (NSRI). NSRI is, thus, completely different from BIS as an anesthetic depth index. This study aimed to elucidate the predictability of BIS from NSRI. Methods: We recorded the BIS values when the NSRI values ranged from 0 to 20, 21 to 50, 50 to 70, 71 to 90, and 91 to 100 in patients under desflurane/opioid anesthesia (group D, n = 20) and those under propofol/opioid anesthesia (group P, n = 20). We examined the predictability of BIS from NSRI using linear regression analysis. Results: In both groups, linear regression analysis demonstrated the difficulty in the prediction of BIS from NSRI. Many patients in both groups showed a BIS value of 60 or less when the NSRI values ranged from 71 to 100 and a BIS value of less than 40 when the NSRI values ranged from 0 to 20. Conclusions: It is difficult to predict BIS from NSRI, and the observed discrepancies between NSRI and BIS suggest that simultaneous monitoring of NSRI and BIS might have clinical utility in guiding appropriate anesthetic depth.