Effect Of Dexmedetomidine On Postoperative Delirium Under Cerebral Oxygen Saturation Monitoring In Elder Patients Undergoing Thoracic Surgery

Objective:To investigate the effect of Dexmedetomidine on postoperative delirium under cerebral oxygen saturation monitoring in elder patients undergoing thoracic surgery.Methods:110 elderly patients undergoing elective thoracic surgery in our hospital were selected as the research objects;The patients were evaluated with the suggested mental state examination scale before operation.None of them had preoperative cognitive impairment;Age>60 years old,ASA grade I～III,were randomly divided into two groups（n=55 each）:Dexmedetomidine group（group D）and control group（group C）.Patients in the group D were given a loading dosage of dexmedetomidine 1μg·kg^-1intravenously 15 min after the induction of general anesthesia,followed by continuous infusion 0.3～0.5μg·kg^-1·h^-1during the operation until 30 mins before the end of operation.Patients in the control group were given 0.9%saline solution instead of dexmedetomidine.The r SO₂was monitored intra-operatively with brain oxygen saturation monitor.Heart rate（HR）,mean arterial pressure（MAP）and regional oxygen saturation（r SO₂）were collected before induction of anesthesia（T₀）,3 min after induction（T₁）,immediately after intubation（T₂）,before single-lung ventilation（T₃）,30min after single-lung ventilation（T₄）,60 min after single-lung ventilation（T₅）,and after operation（T₆）.Record the duration of one-lung ventilation,dosage of propofol and remifentanil,the incidence of postoperative delirium and postoperative recovery.The cognitive function status of patients was performed by MMSE scale the day before surgery.Confusion Assessment Method-Chinese Reversion（CAM-CR）scale was used to evaluate the incidence of postoperative delirium from 1 to 7 days after surgery.Results:（1）Within 7 days after operation,the incidence of POD in group D was significantly lower than that in group C（P<0.05）.（2）There was no significant difference between the two groups in terms of gender,age,BMI,ASA scale,NYHA grade,chronic diseases and single lung ventilation time（P>0.05）.（3）HR,MAP,S_pO₂and r SO₂were monitored during operation:the r SO₂at T₄was significantly lower than that at T₀（P<0.05）;Map and HR of patients in group C at T₂time point were higher than those at T₀time point（P<0.05）;At T₂time point,MAP in group D was significantly lower than that in group C（P<0.05）;MAP in T₁,T₃and T₄was significantly lower than that in T₀（P<0.05）.（4）There was no significant difference between the two groups in extubation time,PACU residence time,postoperative time out of bed,thoracic drainage tube extubation time and hospital stay（P>0.05）.（5）In terms of postoperative complications,there was no significant difference in nausea and vomiting,pulmonary infection,atelectasis,pulmonary embolism,postoperative bleeding and arrhythmia between the two groups（P>0.05）.Conclusion:Dexmedetomidine reduced the incidence of POD in elder patients undergoing thoracic surgery within 7 days after surgery under monitoring of cerebral oxygen saturation.