Correlation Between Blood Pressure Variability And Postoperative Delirium And Postoperative Cognitive Dysfunction In Elderly Patients Undergoing Non-cardiac Surgery

Objective: Postoperative delirium?POD? and postoperative cognitive dysfunction?POCD? are most common postoperative complications and life-threatening complications in elderly patients. The goal of this study was to observe the correlation between blood pressure variability?BPV? and incidence of POD and POCD in elderly patients undergoing non-cardiac surgery, meanwhile to explore other related risk factors of POD and POCD, and to prevent and treat POD and POCD. Methods:One hundred and fifty patients were selected. Inclusion criteria:?1?Age?65;?2?Anesthesia method was general anesthesia with endotracheal intubation;?3?ASA?3?³;?4?Non-cardiac surgery;?5?Operation time was less than three hours. Exclusion criteria:?1?Patients refused the study;?2?Illiterates and communication barrier;?3?Patients with dementia before surgery;?4?Patients could not provide complete observation data;?5?Patients with perioperative hypoxemia?SPO2<90%?;?6?Bleeding volume was too much?>400ml? and the patients received blood transfusion treatment;?7?Patients with encephalosis before surgery. One day before the operation, the mentality of patients were evaluated by Minimum Mental State Examination?MMSE?,and the sex, age, height and weight of the patients were recorded. The anesthesia drugs were Sufentanil citrate, propofol and cisatracurium besilate, sevoflurane and remifentanil hydrochloride. The bispectral index?BIS? was maintained between forty and sixty,and the partial pressure of end-tidal carbon dioxide?PETCO2? was maintained between thirty-five and forty-five mm Hg during surgery. The bleeding volume of patients was recorded at the end of operation. Patient controlled intravenous analgesia?PCIA? was used at the three days after the operation. The systolic blood pressure?SBP?, mean arterial pressure?MAP? and diastolic blood pressure?DBP? from skin incision to the end of the surgery were recorded every five minutes. Intraoperative hypotension and hypertension were recorded.The level of tumor necrosis factor-??TNF-?? and interleukin-6?IL-6? were determined in twenty-four hours after the surgery. Visual Analogue Scale?VAS? was used to evaluated the degree of pain during three days after surgery.POD was measured by the Richmond Agitation-Sedation Scale?RASS? and the Confusion Assessment Method for the Intensive Care Unit?CAM-ICU? on the three postoperative days. On the first seven postoperative days, the cognitive function was evaluated by MMSE. The BPV was represented by the variance of blood pressure.The patients were divided into POD group and non-POD group according to the result of CAM-ICU, or divided into POCD group and non-POCD group by the pre-and-postoperative difference of MMSE. Data were analysed using t-test, Chi-squared test,Fisher exact test and logistic regression multivariable models.Results:1.Incidence of POD and POCD:There were one hundred and fifty patients which were accorded with the inclusion criteria came into the study,and thirty patients developed POD in the three days after surgery.The incidence of POD was 20%. Seventy-nine patients of one hundred and fifty patients were evaluated by MMSE at the seventh day after surgery, and twenty-four patients developed POCD.The incidence of POCD was 30.4%.In Seventy-nine patients,the incidence of POCD was 66.7% in patients with POD,and the incidence of POCD was 21.9% in patients without POD.The difference was statistically significant?P < 0.05?2.Comparison of general data:There were no significant differences between POD group and non-POD group in sex,age,weight,body mass index?BMI?,type of operation,bleeding volume and score of VAS?P>0.05?. The age?70 years old in non-POD group was less than that in POD group, and the preoperative MMSE score in non-POD group was higher than that in POD group, the differences were statistically significant?P<0.05?.There were no significant differences between POCD group and non-POCD group in sex,weight, body mass index?BMI?, type of operation, bleeding volume and score of VAS?P>0.05?,and there were significant differences between POCD group and non-POCD group in age, the age ? 70 years old and preoperative MMSE.3.Comparison of intraoperative blood pressure: SBP variability,MAP variability and DBP variability in POD group were higher than those in non-POD group,the differences were statistically significant?P<0.05?.There was no significant difference between POD group and non-POD group in incidence of intraoperative hypotension?P>0.05?.Incidence of intraoperative hypertension in POD group was higher than that in non-POD group,the difference was statistically significant?P < 0.05?.There were no significant difference between POCD group and non-POCD group in intraoperative BPV,incidence of intraoperative hypotension and incidence of intraoperative hypertension?P > 0.05?.4.Comparison of postoperative inflammatory factors?TNF-? and IL-6?:There were significant differences between POD group and non-POD group?P<0.05?,and there were no statistically significant differences between POCD group and non-POCD group?P > 0.05?. 5.Multivariate logistic regression analysis: The correlative factors of POD were the age?70 years old?P=0.033, OR:3.248, 95%CI: 1.098⁹.827?, preoperative cognitive impairment?low preoperative MMSE score??P=0.036, OR:0.756, 95%CI: 0.581 0.982?,high MAP variability?P=0.007, OR:1.009, 95%CI: 1.002¹.015?,high levels of TNF-??P=0.024,OR:1.088,95%CI: 1.011¹.171? and IL-6?P=0.012,OR:1.089,95%CI: 1.019¹.164?. The correlative factors of POCD were the age ? 70 years old?P=0.003, OR:6.472, 95%CI: 1.853²2.611?, preoperative cognitive impairment?low preoperative MMSE score??P=0.013, OR:0.697, 95%CI: 0.524⁰.927?. Conclusion: 1.The patients with POD are prone to POCD.2. The age?70 years old,score of preoperative MMSE, intraoperative MAP variability, levels of postoperative TNF-? and IL-6 have correlation with incidence of POD.3. The age?70 years old,score of preoperative MMSE have correlation with incidence of POCD.