Anaesthetic depth and delirium after major surgery: a randomised clinical trial

Abstract

Background: Postoperative delirium is a serious complication of surgery associated with prolonged hospitalisation, longterm cognitive decline, and mortality. This study aimed to determine whether targeting bispectral index (BIS) readings of 50 (light anaesthesia) was associated with a lower incidence of POD than targeting BIS readings of 35 (deep anaesthesia). Methods: This multicentre randomised clinical trial of 655 at-risk patients undergoing major surgery from eight centres in three countries assessed delirium for 5 days postoperatively using the 3 min confusion assessment method (3D-CAM) or CAM-ICU, and cognitive screening using the Mini-Mental State Examination at baseline and discharge and the Abbreviated Mental Test score (AMTS) at 30 days and 1 yr. Patients were assigned to light or deep anaesthesia. The primary outcome was the presence of postoperative delirium on any of the first 5 postoperative days. Secondary outcomes included mortality at 1 yr, cognitive decline at discharge, cognitive impairment at 30 days and 1 yr, unplanned ICU admission, length of stay, and time in electroencephalographic burst suppression. Results: The incidence of postoperative delirium in the BIS 50 group was 19% and in the BIS 35 group was 28% (odds ratio 0.58 [95% confidence interval: 0.38e0.88]; P¼0.010). At 1 yr, those in the BIS 50 group demonstrated significantly better cognitive function than those in the BIS 35 group (9% with AMTS 6 vs 20%; P<0.001).

Spectral Entropy Monitoring Accelerates the Emergence from Sevoflurane Anesthesia in Thoracic Surgery: A Randomized Controlled Trial

“…It has been reported that deep anesthesia and electroencephalogram suppression were associated with the development of postoperative delirium [ 29 ]. However, it remains controversial whether anesthetic depth monitoring protects against postoperative delirium and cognitive function decline, with benefits reported in some studies [ 30 , 31 , 32 ] but not in others [ 33 , 34 ]. These contrasting results might be explained by the differences in the patient attributes, anesthetic regimens, and protocol rigor [ 30 , 31 , 32 , 33 , 34 ].…”

“…However, it remains controversial whether anesthetic depth monitoring protects against postoperative delirium and cognitive function decline, with benefits reported in some studies [ 30 , 31 , 32 ] but not in others [ 33 , 34 ]. These contrasting results might be explained by the differences in the patient attributes, anesthetic regimens, and protocol rigor [ 30 , 31 , 32 , 33 , 34 ]. Given the multiple contributing causes and inadequate understanding of pathophysiology, it is challenging to prevent or treat postoperative delirium in the high-risk population [ 35 ].…”

Postoperative Delirium: The Search for Effective Interventions

“…In this case, the statistically different incidence in POD may be interpreted as either a false positive, or due to a small between group difference in the time spent with burst suppression. In contrast, the trials by Chan et al9 and Evered et al10 investigating the relationship between pEEG-guided anesthetic depth and POD demonstrated a bigger difference in the depth of anesthesia between groups; mean BIS values between groups were 38.6 (6.5) versus 53.2 (8.9)9 and 38.7 (3.9) versus 50.7 (4.4),10 respectively. This wider group separation was associated with significant reductions in POD from 24.1% to 15.6% ( P =0.01)9 and from 28% to 19% ( P =0.01) 10…”

Délirium postopératoire, COVID-19 et analyses bayésiennes

“…L’étude d’Evered et al, publiée en août 2021, dans The British Journal of Anaesthesia (BJA) [7] , est une étude ancillaire de l’étude BALANCED [8] . Elle s’intéresse à l’incidence du DPO en fonction de la profondeur de l’anesthésie générale monitorée par BIS chez des patients à risque de DPO.…”