Effect And Possible Mechanism Invitation Of Anesthetic Depth On Postoperative Delirium In Elderly Patients

Objective 1.To investigate the available mechanism of POD, we elevated the incidence of POD in the elder patients who were undergoing general anesthesia in different depth of anesthesia. 2.To investigate the further available mechanism of POD, we also elevated the incidence of POD in the elder rat model in different depth of anesthesia.Method Part 1. Clinical Observation 120 elder patients prepared for selective cholecystectomy, aged from 65-75, were randomly divided into A1（BIS 40-49 by propofol）, A2（BIS 50-59 by propofol）, A3（BIS 60-69 by propofol）, B1（BIS 40-49 by sevoflurane）, B2（BIS 50-59 by sevoflurane） and B3（BIS 60-69 by sevoflurane） groups. Mini-mental state examination was conducted respectively at the time of 24 h pre-operative, post-operative 3d, 5d and 7d. CAM-CR score was conducted within 72 h. And Price-Henry score was conducted at the time of 24 h, 48 h and 72 h. Additionally, blood was taken respectively 10 min before induction of anesthesia（T₀）, post-operative 24h（T₁）, 3d（T₂）, 5d（T₃）, and 7d（T₄）, for the detection of serum concentration of NSE and S100β protein.Part 2. Animal Experiment 120 elder rats took food and water freely in experimental period were randomly divided into A1（BIS 40-49 by propofol）, A2（BIS 50-59 by propofol）, A3（BIS 60-69 by propofol）, B1（BIS 40-49 by sevoflurane）, B2（BIS 50-59 by sevoflurane） and B3（BIS 60-69 by sevoflurane） groups. The incidence of POD in elder rat was assessed in different depth of anesthesia, and then the death of neurons, and the expressions in Bid, Bim, Puma and caspase-3 were assessed by Annexin/PI, real-time PCR and western blot respectively.Results Part 1. Clinical Observation There was no significant difference of age, gender, index of body weight, the time of anesthesia and surgery, loss and input of fluid, and Price-Henry score（P>0.05）. In total intravenous anesthesia, compared with Group A1, MMSE score was up-regulated and incidence of POD was down-regulated on post-operative 3d, and 5d in Group A2, and compared with Group A3, MMSE score was up-regulated and incidence of POD was down-regulated on post-operative 3d, and 5d in Group A2（P<0.05）. Additionally, in intravenous inhalational anesthesia, compared with Group B1, MMSE score was up-regulated and incidence of POD was down-regulated on post-operative 3d, and 5d in Group B2, and compared with Group B3, MMSE score was up-regulated and incidence of POD was down-regulated on post-operative 3d, and 5d in Group B2（P<0.05）. Moreover, in total intravenous anesthesia, compared with T₀, the expression of NSE and S100β protein was higher A1-A3 groups at the time of T₁-T₃（P<0.05）. Moreover, compared with A1, the expression of NSE and S100β protein was down-regulated in Group A2, and compared with A3, the expression of NSE and S100β protein was down-regulated in Group A2（P<0.05）. Additionally, in intravenous inhalational anesthesia, similar results were found.Part 2. Animal Experiment Compared with A1 and A3, The incidence of POD in elder rat was decreased and the death of neurons, and the expressions in Bid, Bim, Puma and caspase-3 were decreased in Group A2（P<0.05）. Compared with preoperative condition, the incidence of POD in elder rat was increased and the death of neurons, and the expressions in Bid, Bim, Puma and caspase-3 were increased（P<0.05）. Additionally, in inhalational anesthesia, similar results were also found.Conclusion Part 1. Clinical Observation 1. The incidence of POD was increased with too deep（BIS 40⁴9） /or shallow（BIS 60⁶9） depth of anesthesia in elder patients. 2. The difference in depth of anesthesia（too deep /or shallow） in elder patients leading to increase in the incidence of POD might result from injury of neurons.Part 2. Animal Experiment 1. The difference in depth of anesthesia（too deep /or shallow） in elder rats leading to increase in the incidence of POD might result from apoptosis of neurons. 2. The difference in depth of anesthesia（too deep /or shallow） in elder rats leading to increase in the incidence of POD might result from the increase of Bid, Bim, Puma and caspase-3.