Spinal Anesthesia with Targeted Sedation based on Bispectral Index Values Compared with General Anesthesia with Masked Bispectral Index Values to Reduce Delirium: The SHARP Randomized Controlled Trial

Abstract

Background Reducing depth of anesthesia and anesthetic exposure may help prevent delirium, but trials have been conflicting. Most studies were conducted under general anesthesia or in cognitively impaired patients. It is unclear whether reducing depth of anesthesia beyond levels consistent with general anesthesia reduces delirium in cognitively intact patients. The authors’ objective was to determine whether a bundled approach to reduce anesthetic agent exposure as determined by Bispectral Index (BIS) values (spinal anesthesia with targeted sedation based on BIS values) compared with general anesthesia (masked BIS) reduces delirium. Methods Important eligibility criteria for this parallel-arm randomized trial were patients 65 yr or greater undergoing lumbar spine fusion. The intervention group received spinal anesthesia with targeted sedation to BIS greater than 60 to 70. The control group received general anesthesia (masked BIS). The primary outcome was delirium using the Confusion Assessment Method daily through postoperative day 3, with blinded assessment. Results The median age of 217 patients in the analysis was 72 (interquartile range, 69 to 77). The median BIS value in the spinal anesthesia with targeted sedation based on BIS values group was 62 (interquartile range, 53 to 70) and in the general anesthesia with masked BIS values group was 45 (interquartile range, 41 to 50; P < 0.001). Incident delirium was not different in the spinal anesthesia with targeted sedation based on BIS values group (25.2% [28 of 111] vs. the general anesthesia with masked BIS values group (18.9% [20 of 106]; P = 0.259; relative risk, 1.22 [95% CI, 0.85 to 1.76]). In prespecified subgroup analyses, the effect of anesthetic strategy differed according to the Mini-Mental State Examination, but not the Charlson Comorbidity Index or age. Two strokes occurred among patients receiving spinal anesthesia and one death among patients receiving general anesthesia. Conclusions Spinal anesthesia with targeted sedation based on BIS values compared with general anesthesia with masked BIS values did not reduce delirium after lumbar fusion. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Clinical Observation of General Anesthesia Combined with Spinal Anesthesia in Elderly Patients with Chronic Obstructive Pulmonary Disease

“…In contrast, SA uses a small number of anesthetics and injects anesthesia into the spinal canal space to block neurons. For this reason, the degree of damage to the cognitive function of the patient is low, and the postoperative cognitive function of the patient can be improved [ 21 , 32 , 33 ]. Finally, this work compared the differences in the probability of postoperative respiratory events among patients.…”

Targeting Depth of Anesthesia to Prevent Delirium: Comment

“…2,3 The adjusted hazard ratio associated with a 1-mmHg increase in time-weighted average of mean arterial pressure less than 65 mmHg was 1.11 (95% CI, 1.03 to 1.20). 2 The study by Brown et al 1 found that the lowest mean arterial pressure was similar in both groups (general anesthesia, 59 [51 to 64] vs . spinal anesthesia, 60 [52 to 64]); however, the relationship between intraoperative hypotension and the subsequent development of delirium might be more of a cumulative exposure response than a single threshold.…”

“…Brown et al 1 nicely described their work comparing spinal anesthesia with targeted sedation based on Bispectral Index values compared with general anesthesia (masked Bispectral Index) and the outcome of delirium. Intraoperative hypotension has been associated with delirium.…”

Targeting Depth of Anesthesia to Prevent Delirium: Comment

“…We read with great interest the recent article by Brown et al 1 regarding the impact of Bispectral Index (BIS)–guided sedation on the incidence of postoperative delirium during spinal anesthesia for spine surgery compared with BIS-masked general anesthesia. We appreciated the originality and efforts of the authors to clarify a still controversial topic such as the connection between depth of the hypnotic component of anesthesia and postoperative delirium.…”