Monitoring Depth of Hypnosis: Mid-Latency Auditory Evoked Potentials Derived aepEX in Children Receiving Desflurane-Remifentanil Anesthesia

BACKGROUND: The aepEXplus monitoring system, which uses mid-latency auditory evoked potentials to measure depth of hypnosis, was evaluated in pediatric patients receiving desflurane-remifentanil anesthesia. METHODS: Seventy-five patients, 1–18 years of age (stratified for age; 1–3, 3–6, 6–18 years, for subgroup analyses), were included in this prospective observational study. The aepEX and the bispectral index (BIS) were recorded simultaneously, the latter serving as a reference. The ability of the aepEX to detect different levels of consciousness, defined according to the University of Michigan Sedation Scale, investigated using prediction probability ( P k ), and receiver operating characteristic (ROC) analysis, served as the primary outcome parameter. As a secondary outcome parameter, the relationship between end-tidal desflurane and the aepEX and BIS values were calculated by fitting in a nonlinear regression model. RESULTS: The P k values for the aepEX and the BIS were, respectively, .68 (95% CI, 0.53–0.82) and .85 (95% CI, 0.73–0.96; P = .02). The aepEX and the BIS had an area under the ROC curve of, respectively, 0.89 (95% CI, 0.80–0.95) and 0.76 (95% CI, 0.68–0.84; P = .04). The maximized sensitivity and specificity were, respectively, 81% (95% CI, 61%–93%) and 86% (95% CI, 74%–94%) for the aepEX at a cutoff value of >52, and 69% (95% CI, 56%–81%) and 70% (95% CI, 57%–81%) for the BIS at a cutoff value of >65. The age-corrected end-tidal desflurane concentration associated with an index value of 50 (EC 50 ) was 0.59 minimum alveolar concentration (interquartile range: 0.38–0.85) and 0.58 minimum alveolar concentration (interquartile range: 0.41–0.70) for, respectively, the aepEX and BIS ( P = .69). Age-group analysis showed no evidence of a difference regarding the area under the ROC curve or EC 50 . CONCLUSIONS: The aepEX can reliably differentiate between a conscious and an unconscious state in pediatric patients receiving desflurane-remifentanil anesthesia.