Effect Of Nocturnal Dexmedetomidine Twice Postoperatively On Perioperative Neurocognitive Disorders In Elderly Patients With Malignant Tumor

Objective:To study the effect of nocturnal dexmedetomidine twice postoperatively on perioperative neurocognitive disorders in elderly patients with malignant tumor.Methods:Eighty consecutive eligible and consenting patients with malignant tumor undergoing elective surgery under general anesthesia and postoperatively admitted to surgical monitored ward,American Society of Anesthesiologists physical status I or II,aged 65 yrs or over,were enrolled,whose cardiopulmonary function was not severe abnormal and claimed no history of head surgery or trauma.Patients were divided into 4 groups by random number table:placebo group?group 0?,dexmedetomidine0.1?g?kg^-1?h^-1 group?group 1?,dexmedetomidine 0.2?g?kg^-1?h^-1 group?group2?,dexmedetomidine 0.3?g?kg^-1?h^-1 group?group 3?.Each patient was interviewed on the day before surgery,and the preoperative sleep level was assessed using the Self-Rating Scale of Sleep.The neuropsychological testing was assessed and plasma cortisol concentration were measured preoperatively.All patients underwent combined anesthesia with intravenous inhalation and without preoperative medication.After entering the operation room,an upper limb venous line and right internal jugular venous line were inserted.The pulse oximetry?SpO₂?,electrocardiogram?ECG?,central venous pressure?CVP?and invasive arterial pressure?ABP?were monitored.Then the patient was anesthetized by a rapid induction proceeded by sufentanil?0.2¹?g/kg?,etomidate?0.2⁰.3mg/kg?and cisatracurium?0.2⁰.3mg/kg?,and be intubated with a single-lumen endotracheal tube?7.5#for male and 7.0#for female?.During the maintenance of anesthesia,remifentanil 0.1-0.3?g?kg^-1?h^-11 was continuously administered intravenously and sevoflurane1%-3%was adjusted to keep BIS from 40 to 60.Cisatracurium 0.05mg/kg was given intravenously every 30⁴0 minutes.When the spontaneous breathing was recovered,and the patient could obey the instruction,the tracheal tube was removed and the patient was sent back to the monitored ward.The dexmedetomidine was administered intravenously from 9:00 pm to the following 6:00 am at the surgery day and the first day after surgery at the speed of 0.1,0.2 and 0.3?g?kg^-1?h^-11 in group 1,2 and 3 respectively.The VAS score was used to assess the patient's pain and the remedy analgesics were used when VAS score was over 3 points.On the first day,the second day and the seventh day after surgery the patient's sleep quality was evaluated.On the second day and the seventh day after surgery,the plasma concentration of cortisol was measured?measurement time was 8 am,4 pm?.On the 7th day,the neuropsychological testing was assessed again.The patient's general information and ASA score,operative time was recorded.The SRSS sleep score,as well as the results of the cognitive results,postoperative sleep quality and the concentration of plasm cortisol was recorded.The neuropsychological testings include:Simple Intelligence State Examination?MMSE?,Clock drawing test?CDT?,Trail making test?TMT?,Animal Fluency Experiment?AFT?,Verbal fluency test?VFT?.Ten non-surgical in-patient patients at the same time were selected into group C.Cognitive function tests were performed on the experimental and control patients at the same time by the same investigator.Results:1.Patients'baseline characteristics:there were no significant differences in age,ASA,BMI and operative time among the 4 groups?P>0.05?.2.Among the 4 groups the incidence of cognitive impairment was 55%in group 0,40%in group 1,25%in group 2,and 15%in group 3,respectively.The cognitive function in group 3 was improved significantly?P<0.05?.3.The changes of the concentrations of plasm cortisol in different groups at different time points were analyzed by analysis of variance of repeated measurement design.The changes among groups were statistically difference?F=3.454,P=0.021?.The difference between changes of the concentrations of plasm cortisol at different time points was statistically significant?F=3.621,P=0.032?,there was an interaction between the group and the time point?F=2.505,P=0.025?.The individual effects were further analyzed.There was no significant difference among the four groups except at the first time point?P<0.05?,and in other times,four groups were statistically significant?P>0.05?.And as time goes on,fluctuation gradually decreases.The results of the pairwise comparison showed that there was no difference between the group 0 and the group 1?P=0.696?,while compared with group 0,there is different in the group 2?P=0.016?and in the group 3?P=0.017?,but there was no difference between the group 2 and the group 3?P>0.05?.The data?P=0.981?showed that the fluctuation level gradually decreased with the increase of the dose and there is the best effect in group 2.4.There were no significant differences in preoperative SRSS among the4 groups?P>0.05?.The number of night awakenings on the 2nd day after surgery was analyzed by repeated measures design.The difference between the groups was statistically significant?F=2.888,P=0.041?.The results of the pairwise comparison showed that the group 0,the group 1,and the group 2were all different from the group 3,and P was 0.009,0.026 and 0.039,respectively.The use of dexmedetomidine reduced the number of awakenings on the second day after surgery,that in the third group was significantly reduced.There were no statistical differences in the other groups and indications?P>0.05?.5.Compared with the other three groups,the incidence of bradycardia in group 3 increased significantly?P<0.05?.Conclusion:1.Nocturnal intravenous dexmedetomidine(0.2,0.3?g·kg^-1·h^-1)can effectively improve the postoperative sleep quality of elderly patients with malignant tumors,enhance the circadian rhythm recovery of cortisol endocrine;2.Nocturnal intravenous dexmedetomidine(0.3?g·kg^-1·h^-1)significantly reduce incidence of perioperative neurocognitive disorders in elderly patients with malignant tumors who were transferred to the surgical monitored ward.3.Perioperative sleep-wake cycle,cortisol endocrine and other recent rhythms can help prevent postoperative neurocognitive impairment in elderly patients with malignant tumors.4.It is safer to administer dexmedetomidine(0.2?g·kg^-1·h^-1)at nigthtime twice postoperatively for the elderly patients with malignant tumors who were transferred to the surgical monitored ward..