Effect Of Preoperative Adjustment Of Sleep Rhythm On Postoperative Cognitive Function Of Elderly Patients

Background:Perioperative neurocognitive disorders（PND）is a common complication after major orthopedic surgery.PND is related to long-term unfavorable results.After the occurrence of PND,it often leads to lower quality of life and higher postoperative mortality.Therefore,it is urgent to find a way to prevent PND.Objective:To explore the effects of preoperative use of Dexmdetomidine（Dex）to adjust the sleep-wake rhythm on the cognitive function of elderly patients after surgery and the outcome after dexmedetomidine intervention.Methods:90 elderly patients who underwent unilateral hip arthroplasty for the first time in Dongfeng General Hospital of Sinopharm were selected as the research objects.All patients were treated with spinal anesthesia.The patients were randomly divided into 3 groups:high-dose Dex group（n=30）,low-dose Dex group（n=30）and control group（normal saline group,n=30）.The high-dose Dex group was given 2μg/kg dexmedetomidine nasal drip every night a week before surgery,the low-dose Dex group was given 1μg/kg dexmedetomidine in the nasal cavity,and the control group was given2m L 0.9%normal saline.Compare the 3 groups of subjective and objective sleep quality and structure,subjective pain score changes,10 hours of night hemodynamic changes and postoperative cognitive function.The patients’pain and sleep numerical rating scale（NRS）and the occurrence of adverse reactions were recorded before and after administration.Record the preoperative Mini-mental state examination（MMSE）scores and postoperative MMSE scores at 1,3,and 7 days after the operation,neurocognitive disorders in the perioperative period and and the incidence of postoperative delirium（POD）were recorded.Results:Compared with the control group,the MMSE score of the high-dose Dex group rose back to the preoperative score at 3 days after surgery（P>0.05）,the incidence of PND was significantly reduced at 7 days after surgery（P<0.05）,and the sleep NRS score significantly decreased（P<0.05）,the total sleep time is prolonged,the sleep efficiency is improved,the non-rapid eye movement sleep（NREM）phase 2 time is prolonged,and its proportion in the total sleep time is increased（P<0.05）,The N3period time increases,the rapid eye movement sleep（REM）time decreases,and its proportion to the total sleep time decreases（P<0.05）.Compared with the control group,the sleep NRS score of the low-dose Dex group decreased（P<0.05）,the N2 period time and its proportion increased（P<0.05）,and the proportion of REM decreased（P<0.05）.The MMSE of the low-dose Dex group and the control group both recovered to the preoperative level in 7^th days after operation（P>0.05）.There was no significant difference in the incidence of PND between the two groups（P>0.05）.The pain NRS score of the high-dose Dex group decreased,but the difference between the pain NRS scores of the 3 groups after administration was not statistically significant（P>0.05）.The adverse reactions in the high-dose Dex group showed a significant increase in the incidence of dry mouth and dry nose.There was no significant difference in the incidence of other adverse reactions in the three groups（P>0.05）.In the control group,2 cases of POD occurred within the 7^th day of the operation,the incidence was 6.67%,and neither the high-dose Dex group nor the low-dose Dex group had POD.Conclusion:Dexmetomidine nasal drip at night before operation can improve preoperative sleep-awakening rhythm and sleep structure in a dose-dependent manner,improve sleep quality,alleviate postoperative cognitive impairment and reduce the incidence of PND.