Meta-Analysis of the Prognostic Value of Narcotrend Monitoring of Different Depths of Anesthesia and Different Bispectral Index (BIS) Values for Cognitive Dysfunction after Tumor Surgery in Elderly Patients

Abstract

Objective. To study the effect of Narcotrend monitoring on the incidence of early postoperative cognitive dysfunction (POCD) under different bispectral index (BIS) conditions and the effect of different depths of anesthesia on the incidence of POCD. Methods. We performed a literature search of PubMed, Embase, OVID (database system made by Ovid Technologies, USA), CBM (Chinese Biomedical Literature database), CNKI (China National Knowledge Infrastructure), Wanfang, and VIP databases (full-text database of Chinese sci-tech journals), etc., from the date of the establishment of the database until December 31, 2020. Our meta-analysis was focused on the collection and study of Narcotrend monitoring of different depths of anesthesia. We carefully read the abstracts and full texts of randomized controlled trials on the incidence of POCD in the early postoperative period, and their references were tracked. Data extraction and quality evaluation of the included literature were also performed, and RevMan 5.3 software was used for analysis. Results. In the end, eight articles were included, with a total of 714 patients. The meta-analysis results showed that four articles (255 patients) compared the state of deep anesthesia (BIS 30–40) with conventional anesthesia (BIS 40–60 earlier) after POCD. Also, the incidence of POCD on the first day after deep anesthesia (Narcotrend stage (NTS): negative correlation is currently the most appropriate EEG description; Nd can subdivide the original EEG into six stages and 15 levels (Nd Sg, NTS), namely, A (state of wakefulness) state, B0 B2 (sedated state), C0 C2 (light anesthetic state), D0 D2 (general anesthesia), and E0–E1) was significantly lower than that of conventional anesthesia (NTS DO–D1) (odds ratio (OR) = 0.21, 95% confidence interval (CI): 0.13–0.35, $P<0.00001$ ). Moreover, the incidence of POCD in deep anesthesia (NTS E1) at 7 days after surgery was significantly lower than that of conventional anesthesia (NTS D0) (OR (odds ratio) = 0.45, 95% CI: 0.23–0.91, $P=0.03$ ), while the incidence of POCD 7 days after NTS D2 in conventional anesthesia was significantly lower than that of NTS D0 (OR = 0.42, 95% CI: 0.24–0.71, $P=0.001$ ). Discussion. Deep anesthesia can reduce the incidence of POCD (OR = 0.40, 95% CI: 0.22–0.73, $P=0.002$ ). This meta-analysis included three studies (216 patients) that compared the early postoperative POCD incidence of BIS 40–50 under conventional anesthesia and BIS 50–60; the BIS 40–50 did not significantly reduce the incidence of POCD (OR = 1.11, 95% CI: 0.24–5.24, $P=0.9$ ). The incidence of POCD under deep anesthesia with Narcotrend monitoring was lower than that under conventional anesthesia.