Association between processed electroencephalogram monitoring and postoperative neurocognitive outcomes in cardiac surgery: A randomized controlled trial

Background: In open-heart surgeries, several factors such as extracorporeal circulation, hypothermia, rewarming, and low cardiac output can affect the depth of anesthesia. Current guidelines recommend monitoring end-tidal anesthetic gas concentration or using processed electroencephalogram (EEG) monitoring. This study aimed to evaluate the effects of EEG-guided anesthesia on anesthetic consumption, hemodynamic stability and its effects on postoperative delirium and neurocognitive disorder (NCD) that may develop subsequently. Methods: Fifty adult patients undergoing elective cardiac surgery with cardiopulmonary bypass were randomized into two groups. Elective and adult patients undergoing open heart surgery were included in the study. Group I was anesthetized with a bispectral index value of 40-60. Group II was taken as the control group, and anesthesia was maintained with 1.8% MAC sevoflurane by the conventional method. Total anesthesia and vasopressor consumption were noted at the end of the case. Tests were also performed in the intensive care unit to detect delirium and NCD. Data were analyzed using SPSS v21. Results: According to our findings, propofol, midazolam, and fentanyl consumptions were similar in the two groups, while total sevoflurane consumption was lower in Group I. Group II exhibited significantly higher total sevoflurane consumption (p=0.03) and norepinephrine use (p<0.0001). Postoperative cognitive dysfunction (mini-mental state examination <24) and delirium (Nu-DESC ≥2) were more prevalent in Group II (p=0.037 and p=0.019, respectively). BIS values were significantly lower and suppression durations longer in Group II, which correlated with increased incidence of cognitive dysfunction (rs=0.585, p<0.05). Conclusion: BIS-guided anesthesia during cardiac surgery reduced anesthetic agent consumption and norepinephrine use, and was associated with a lower incidence of postoperative cognitive dysfunction and delirium. EEG suppression duration may serve as a valuable predictor of adverse neurocognitive outcomes.