Effects of dexmedetomidine on postoperative cognitive function in patients undergoing coronary artery bypass grafting

Effects of dexmedetomidine on postoperative cognitive function in patients undergoing coronary artery bypass grafting were investigated. Eighty patients undergoing systemic anesthesia with extracorporeal coronary artery bypass grafting in The People's Hospital of Guangxi Zhuang Autonomous Region from January 2015 to August 2017 were selected and randomly divided into the observation group (n=40) and control group (n=40). The two groups were treated with dexmedetomidine and equal volume of normal saline, respectively. Moreover, safety indexes including EEG bispectral index (BIS) at 30 min before induction of anesthesia (T0), immediately after intubation (T1), when incision was made (T2), when chest was closed (T3), when operation was completed (T4) and at 6 h after operation (T5), intraoperative circulatory system-related complications, cortisol, epinephrine and norepinephrine levels at the end of surgery as well as anesthesia recovery time and postoperative mechanical ventilation time were recorded and compared. All the patients were followed up for 1 week. Mini-mental state examination (MMSE) and Montreal cognitive assessment (MoCA) were administered at 1, 3 and 7 days after operation, and the incidence of intraoperative awareness and postoperative cognitive dysfunction was recorded. BIS value in the observation group was lower than that in the control group (P<0.05) at T1-T4 time points, and the BIS value in the observation group was higher than that in the control group (P<0.05) at T5. Incidence rates of intraoperative arrhythmia, hypertension and hypotension in the observation group was significantly lower than those in the control group (P<0.05). At the end of operation, levels of cortisol, epinephrine and norepinephrine in the observation group were significantly lower than those in the control group (P<0.05). Anesthesia recovery time and postoperative mechanical ventilation time in the observation group was significantly shorter than the time in the control group (P<0.05). MMSE and MoCA scores of the observation group were better than those of the control group (P<0.05). The incidence of cognitive impairment and postoperative cognitive impairment in the observation group was significantly lower than those in the control group (P<0.05). Therefore, it is concluded that dexmedetomidine can effectively reduce the incidence of postoperative cognitive impairment in patients undergoing coronary artery bypass grafting, and it is of high safety for circulatory function.