Effects Of Three Methods Of General Anesthesia On Postoperative Cognitive Function In Elderly Patients

Objective To investigate the effects of three methods of general anesthesia including intravenous compound anesthesia with midazolam, propofol or two drugs combined with inhalation of isoflurane on postoperative cognitive function in elderly patients.Method 45 ASAⅠ~Ⅱpatients aged 60~80yr undergoing laparoscopic operation were randomly assigned to three groups: groupA(n=15), midazolam 0.25mg/kg was injected intravenously for anesthesia induction and midazolam-infusion (0.5~ 1.5μg/kg/min) was used in anesthesia maintenance; groupB(n=15), in anesthesia induction propofol 2mg/kg was given and during surgery propofol-infusion (0.06~0.2mg/kg/min) was used for anesthesia maintenance; groupC(n=15),midazolam 0.05mg/kg and propofol 1.5mg/kg were given for anesthesia induction, in the operation midazolam and propofol were both infused and isoflurane was inhaled at an end-expiratory concentration 0f 1%~2% for anesthesia maintenance. The dosages of midazolam and propofol were identical to groupA and groupB respectively. In anesthesia induction fentanyl 4μg/kg and norcurium 0.1mg/kg were given in three groups additionally. In anesthesia maintenance fentanyl was given 1μg/kg every 30min and norcurium 0.05mg/kg every 30~40min in three groups. The vital signs and AAI were monitored. In order to that AAI was maintained in 10~20 and MAP in 85%~115% of preoperative values, the dosages of infusion and concentration of isoflurane were adjusted according to the values of AAI and MAP. All drugs were discontinued when the laparoscope was taken out. The cognitive function tests were performed before surgery and at early recovery time(5min, 15min, 30min), medium recovery time(30min, 1h, 2h) and late recovery time(4h,24h, 72h) after awakening. All of analyses were performed by SPSS 11.5 software package. Measurement data were presented as means±SD, and categorical data were presented as rate. The differences of scores between preoperative and every course after awake were analyzed by paired-samples t test. One-way ANOVA were analyzed the differences of scores in every period after awakening between groups. P<0.05 was considered statistically significant in all tests.Result 1. All patients were similar in age, sex, education years, level of preoperative cognitive function and anesthesia time.(P>0.05). 2. There was no significant difference of HR, MAP, SpO2 and AAI of patients during surgery(P>0.05). 3. Awakening time of patients in groupA(19.02±3.25min)was longer than groupB(13.65±2.28min)and groupC(10.76±2.42min)(P<0.05), and there was no significant difference between the two latter. 4. Early recovery: At 5min after awakening the scores of patients in groupA were significantly lower than preoperative values, groupB and groupC (P<0.05). But at 15min after awakening groupA returned to preoperative level. And there was no significant difference between others two groups at every time points(5min, 15min, 30min ) (P>0.05). 5. Medium recovery: At 30min after awakening the scores decreased significantly in patients of three groups compared with preoperative values (P<0.05). GroupA scored lowliest (P<0.05) and groupB, groupC by turns (P<0.05). At 1h after awakening the scores of groupA and groupB increased significantly and there was significantly difference between them (P<0.05), but they were all lower than preoperative values (P<0.05). At this time the scores of patients in groupC returned to preoperative level. And so did groupB at 2h, Yet the cognitive function level of groupA still lower than preoperative values (P<0.05). 6. Late recovery: At 4h after awakening the scores of patients in groupA and groupB were both lower than preoperative values (P<0.05). GroupA scored lowlier (P<0.05) and there was no significant difference between the scores of groupC and preoperative values (P>0.05). At 24h after awakening the scores of groupB returned to preoperative level (P>0.05), but the cognitive function of groupA had not recovered (P<0.05). At 72h after awakening, the cognitive function level of groupA descent significantly (P<0.05), and there was no significantly difference in other two groups compared with preoperative values (P>0.05).Conclusion Three methods of general anesthesia all have some influence on the cognitive function of elderly patients in three days after surgery. Of the total the effect of midazolam-based anesthesia is most serious and its lasting time is longest, and the influence of propofol-based anesthesia is much slighter. Yet the patients performed with midazolam and propofol intravenous combined with inhalation of isoflurane anesthesia recover most quickly in cognitive function.