Anesthesia Depth Increases Delirium Incidence

Monitoring of Anesthesia Depth Reduces the Incidence of Postoperative Delirium and Preserves Memory Abilities Better in the High Risk Elderly

This study aimed to determine whether targeting bispectral index (BIS) readings of 55 (light anaesthesia) was associated with a lower incidence of delirium, dementia (POD), POCD and mortality but higher rates of awareness and complications than a standard of care anaesthesia blinded to depth monitoring.

Design: Randomised-controlled, double blind study, monocentric Setting: Level 2 medical center, major surgery (non cardiac) Ethics: Ethical approval for this study (Ethikkommission II der Ruprecht-Karls-Universität Heidelberg 2013-627N-MA) was provided by the Ethical Committee II University Medicine Mannheim, University of Heidelberg, Germany (Chairperson Prof W. Striebel) on Mai 12th 2008.

Patients: n=130, aged > 70y Intervention: Light anesthesia (BIS 55 +/-5) vs. Standard of Care (BIS- blinded) Main outcome measures: Incidence of awareness, delirium, postoperative cognitive deficit (POCD), dementia (POD), memory (MAT with a computerized score for verbal working&short term, figural working&short term memories and well as attention level) Second aims: mortality, complications

Inclusion Criteria:

• scheduled for major surgery above 60 min duration
• informed consent

Exclusion Criteria:

• emergency surgery with large blood loss and/or preoperative cardiovascular instability, scheduled regional or neuraxial anesthesia, language barriers with the unability to understand a German audio tape, unability or unwillingness to consent,hearing disabilities