Unwanted spontaneous responsiveness and burst suppression in patients undergoing entropy-guided total intravenous anesthesia with target-controlled infusion: An observational prospective trial.

To estimate the incidence of unwanted spontaneous responsiveness and burst suppression (BSupp) in patients undergoing state entropy (SE) and surgical pleth index (SPI)-guided total intravenous anesthesia (TIVA) with target-controlled infusion (TCI). Observational, prospective, single-center study. Operating room. 107 adult (<65 years) and elderly (≥65 years) women undergoing breast surgery. Propofol-remifentanil TIVA-TCI-guided by SE for depth of anesthesia monitoring (target value 40–60) and SPI for antinociception monitoring (target value 20–50) without neuromuscular blockade. Age; body mass index; American Society of Anesthesiologists physical status classification; concentration at the effect site of propofol (CeP) and remifentanil (CeR) at loss of responsiveness (LoR), median during anesthesia maintenance (MdM), and at return of responsiveness (RoR); propofol infusion duration; incidence of postoperative delirium (POD) with Confusing Assessment Method for the Intensive Care Unit. During SE-SPI-guided TIVA-TCI, 13.1% of patients showed unwanted spontaneous responsiveness, whereas 45.8% showed BSupp. Unwanted spontaneous responsiveness was observed mainly in adults (p < 0.05), and higher CeP RoR (p < 0.05) was registered. BSupp was observed mainly in patients showing a lower CeP MdM (p < 0.01) and CeP RoR (p < 0.05). Unwanted spontaneous responsiveness and BSupp were not associated with significant differences in CeRs. An age-related hysteresis effect was observed, resulting in higher CeP LoR than CeP RoR (p < 0.001). 12.2% of patients showed POD. Only preoperative serum albumin was associated with increased likelihood of POD (p = 0.046). The SE-SPI-guided TIVA-TCI did not prevent unwanted spontaneous responsiveness and BSupp. CeP RoR may be used as a proxy for anesthetic sensitivity. • Unwanted spontaneous responsiveness and burst suppression may occur during entropy-SPI-guided TIVA-TCI. • Unwanted spontaneous responsiveness occurred in adults with higher concentrations of propofol at return of responsiveness. • Burst suppression occurred in older patients with low effect site concentrations of propofol at return of responsiveness. • Preoperative serum albumin impacted postoperative delirium. [ABSTRACT FROM AUTHOR]