The role of anesthesia in the prevention of postoperative delirium: a systematic review

INTRODUCTION: Postoperative delirium (POD) is defined as an acute neurologic insult characterized by changes in consciousness and cognition, altered perception and a fluctuating course. It leads to poor outcome and increased health care system costs. Considering its high incidence, up to 60%, and the lack of a first-choice treatment, prevention has become a priority. Our aim was to systematically review literature on POD prevention and to identify the role of anesthesia in this context. EVIDENCE ACQUISITION: MEDLINE and EMBASE were searched for studies considering any anesthetic intervention intended to prevent POD. Risk of bias was assessed with the Quality Assessment Tool for Quantitative Studies for original articles and with the R-AMSTAR checklist for systematic reviews. EVIDENCE SYNTHESIS: A total of 27 studies were included. Interventions included pre-, intra-/peri- and postoperative strategies to prevent POD. Only 9 out of 27 studies had high methodological quality. Use of a depth of anesthesia monitor and lighter sedation had the strongest evidence in reduction of POD. Perioperative dexmedetomidine, ketamine, dexamethasone, and antipsychotic administration may reduce the risk of POD. CONCLUSIONS: Methodologically robust studies supporting strategies for preventing POD are still lacking. Based on our analysis, anesthesiologists should consider the intraoperative use of a depth of anesthesia monitor and the choice for a lighter sedation when possible. The administration of preventive medications should be considered very carefully. Considering the multifactorial nature of POD, however, the integration of effective preventive strategies into multidisciplinary programs is advisable and should be the target for future research.