Spinal Anesthesia with Targeted Sedation based on Bispectral Index Values Compared with General Anesthesia with...

Area of Science:

• Anesthesiology
• Geriatric Medicine
• Neurosurgery

Background:

• Conflicting trial results exist regarding whether reducing anesthesia depth and exposure prevents delirium.
• Previous studies often involved general anesthesia or cognitively impaired patients, leaving uncertainty for cognitively intact individuals.
• The benefit of anesthesia depth reduction beyond general anesthesia levels on delirium in cognitively intact patients remains unclear.

Purpose of the Study:

• To determine if a bundled approach reducing anesthetic agent exposure, guided by Bispectral Index (BIS) values, decreases delirium.
• To compare spinal anesthesia with targeted sedation (BIS > 60-70) against general anesthesia (masked BIS) in preventing delirium.

Main Methods:

• A parallel-arm randomized trial included patients aged 65 years or older undergoing lumbar spine fusion.
• Intervention group: Spinal anesthesia with targeted sedation (BIS 60-70). Control group: General anesthesia (masked BIS).
• Primary outcome: Delirium assessed daily using the Confusion Assessment Method through postoperative day 3 by blinded evaluators.

Main Results:

• 217 patients (median age 72) were analyzed. The spinal anesthesia group maintained higher BIS values (median 62) than the general anesthesia group (median 45; P < 0.001).
• No significant difference in incident delirium was observed between the spinal anesthesia (25.2%) and general anesthesia (18.9%) groups (P = 0.259).
• Subgroup analysis indicated the anesthetic strategy's effect varied by Mini-Mental State Examination scores, but not by age or Charlson Comorbidity Index.

Conclusions:

• Spinal anesthesia with targeted sedation, compared to general anesthesia with masked BIS, did not reduce the incidence of delirium after lumbar fusion.
• The findings suggest that this specific bundled approach to reduce anesthetic exposure does not offer a protective effect against postoperative delirium in this patient population.