Nindex monitor performance vs. bispectral index (bis) in anesthesia for cardiac surgery in adult patients // British Journal of Anaesthesia 108 (S2): ii109–ii144 (2012)

Purpose: Monitors of depth of anesthesia use mathematical algorithms to transform the spontaneous or evoked brain electrical activity in numerical indices. These indices are in a scale from 0 to 100, and are correlated with the anesthetic depth. The purpose of this study is to evaluate the performance of the NINDEX monitor (Controles S.A. y Dr. D. Cibils, Uruguay) compared with the BIS monitor (Aspect Medical Systems, MA, USA), in adult patients undergoing anesthesia for cardiac surgery.

Methods: Monitorize the course of anesthesia with both monitors simultaneously, in 30 adult patients undergoing cardiac surgery. Most of them with cardiopulmonary bypass (CPB). The monitors are placed on patients forehead using adhesive electrodes, following the manufacturers recommendations. Numerical indices from the monitors are recorded while the patients are awake, and then during the induction and maintenance of the anesthesia all along the surgery. ANOVA test and curvilinear estimation are used to quantify the statistical significance. p , 0.05 is considered significant, data are presented as mean+sd. 

Results: The mean values found during the monitorization are: BIS NINDEX 93 49 47 50 47 48 49 50 52 98 57 50 56 53 53 52 55 61 While the patients are awake, values are: BIS ¼ 93+4, NINDEX ¼98+1.8 After induction of anesthesia, the values of both monitors are compatible with “general anesthesia”. Those values are: BIS 47–52, NINDEX 50–61. For superficial and deeper anesthesia both values tend to agree: BIS 5459 and 40–43, NINDEX 61–72 and 40–48. NINDEX monitor delay to show the first numerical index is 84+16 seconds larger than BIS monitor. The statistical correlation in both tests used shows a value of p ¼ 0.0001. 

Conclusions: The results found on the 30 patients using NINDEX monitor are very similar to the ones found using the BIS monitor. The data correlation is statistically significant. NINDEX monitor operating characteristics may offer additional benefits, such as disposable electrodes, wireless communication, and the ability to run it in a notebook or net book. This could reduce operating costs, wich is of particular relevance for developing countries like Uruguay.