Intraoperative dexmedetomidine for prevention of postoperative delirium in elderly patients with mild cognitive impairment

Objectives Delirium is the most common postoperative neurological complication and some evidence suggests that dexmedetomidine is associated with a decreased incidence of delirium. This study is designed to assess the effect of dexmedetomidine on postoperative delirium (POD) in elderly patients with mild cognitive impairment (MCI). Methods Sixty geriatric patients with MCI were enrolled and ramdomly divided into two groups by a computer‐generated randomisation sequence: dexmedetomidine group (D group) and normal saline group (C group). Patients in D group received a loading dose of 0.5 μg/kg dexmedetomidine over 10 minutes before anesthesia induction, followed by a continuous infusion of 0.4 μg·kg −1 ·h −1 until 30 minutes before the end of surgery; equal volume of normal saline was given in C group. Blood samples were extracted to detect the concentration of cytokines, including tumor necrosis factor‐α (TNF‐α), interleukin‐10 (IL‐10), heme oxygenase‐1 (HO‐1), matrix metalloproteinase‐9 (MMP‐9), and glial fibrillary acidic protein (GFAP) before anesthesia induction (T 1 ), before suture (T 2 ), and 30 minutes after surgery (T 3 ). Postoperative recovery times were recorded. Delirium was assessed with the 3‐Minute Diagnostic Interview for confusion assessment method during the first 7 days postoperatively. Results POD occurred in 10 (33.3%) of 30 patients in C group, and in 3 (10%) of 30 patients given dexmedetomidine (odds ratio [OR] 0.222, 95% CI 0.054‐0.914; P = 0.028). The serum concentrations of TNF‐α, MMP‐9, and GFAP were significantly increased and IL‐10 was decreased in the C group than in the D group at T 2 and T 3 . No differences were observed between groups in the level of HO‐1. Analysis using random‐effect multivariable logistic regression indicated that POD was associated with GFAP (odds ratio [OR] 16.691, 95% CI 2.288‐121.746; P = 0.005). The positive predictive ability of the multivariate logistic regression model tested by ROC analysis showed an area under the curve of 0.713 (95% CI, 0.584‐0.842). Conclusions Dexmedetomidine can alleviate POD in elderly patients with MCI and may be related to reduce the neuroinflammation by lowering the permeability of blood‐brain barrier.