Background: We analyzed the values of the bispectral index (BIS) and midlatency auditory evoked potentials (MLAEP) and their correlation with the modified Ramsay score (RS) during wakefulness and natural sleep in healthy children without pharmacological sedation.
Methods: Fifty-three healthy children younger than 2-yr-old were studied. Children were evaluated simultaneously using the modified RS, the BIS, and MLAEPs. Each patient was studied only once. The correlation and agreement were studied. The correlation among the three methods was determined using the Spearman Rank Correlation test and the agreement among the methods was assessed using by Cohen's Kappa test.
Results: There was a moderate-to-good correlation (r) among the three methods (P = 0.01): BIS and MLAEP (r = 0.574), BIS and RS (r = -0.504), and MLAEP and RS (r = -0.624). However, the level of agreement (kappa) was only poor to fair: BIS and MLAEP (kappa = 0.392), BIS and RS (kappa = 0.270), and MLAEP and RS (kappa = 0.409). All the correlations were lower in children between 1 and 6 mo-of-age. When the children were asleep (RS: 3-5), the BIS values were higher in children younger than 1 mo-of-age than in children older than 6 mo-of-age (P after Bonferroni correction = 0.028).
Conclusions: The BIS, MLAEP, and RS have a good correlation in children younger than 2 yr not receiving pharmacological sedation, though the level of agreement was poor.