Effects Of Loading Doses Of Dexmedetomidine Infusion At Different Times On Postoperative Delirium After Laparoscopic Radical Resection Of Colorectal Cancer In Elderly Patients

Objective:The purpose of this study was to investigate the effect of intravenous infusion of loading doses of dexmedetomidine at different times on delirium in elderly patients after laparoscopic radical colorectal resection.Methods:A total of 165 elderly patients who underwent laparoscopic radical resection of colorectal cancer under general anesthesia in a hospital from January 2021 to January2022 were selected,with age ranged from 60 to 85 years old,ASA grade I to III,and the preoperative MMSE score was greater than 25 points.Divided into five groups by random number method,33 cases in each group:Group D1（Infusion of 1μg/kg Dex for 10 min on admission）,Group D2（Infusion of of 1μg/kg Dex for 10 min during tracheal intubation）,Group D3（Infusion of of 1μg/kg Dex for 10 min when pneumoperitoneum is established）,Group D4（Infusion of of 1μg/kg Dex for 10 min during laparotomy）,Group S（Pump an equal volume of NS when entering the chamber）.The age,gender,body weight,BMI,preoperative MMSE score,operation time,anesthesia time,tracheal extubation time,urine volume,infusion volume,blood loss and hospitalization time of the five groups of patients were recorded.The mean arterial pressure（MAP）and heart rate（HR）of the five groups of patients were recorded at the time of entering the room（T₁）,at the time of intubation（T₂）,at the time of establishment of pneumoperitoneum（T₃）,at the time of laparotomy（T₄）,and at the end of the operation（T₅）.Record the total use of ephedrine,atropine,remifentanil,propofol,and sevoflurane during surgery.The incidence of POD in the five groups was recorded one day before surgery（T₀）,one day after surgery（T₆）,two days after surgery（T₇）,and three days after surgery（T₈）.Postoperative adverse reactions（nausea and vomiting,respiratory depression）and numerical pain score（NRS）within three days after surgery were recorded.Results:Preoperative general information of the five groups of patients:Gender,age,weight,BMI,preoperative MMSE score,there was no statistically significant difference（P>0.05）.Intraoperative fluid intake and output of the five groups of patients:There was no significant difference in total intraoperative infusion,intraoperative blood loss and intraoperative urine volume（P>0.05）.There was no statistical difference in the operation time,anesthesia time,tracheal extubation time,and hospitalization time of the five groups of patients（P>0.05）.Intraoperative drug use in the five groups of patients:There was no statistical difference in the dosage of sevoflurane,atropine and ephedrine（P>0.05）.There were statistically significant differences in the dosages of propofol and remifentanil among the five groups（P<0.05）,among them,the dosage of propofol and remifentanil in group S was significantly higher than that in groups D1,D2,D3 and D4,while the dosages of propofol and remifentanil in groups D1,D2,D3,and D4 had no statistical significance.Comparison of MAP at each time point in the operation of the five groups of patients:There was no significant difference in MAP between the groups at time points T₁,T₂,T₃,T₄,and T₅.Comparison of HR at each time point during the operation of five groups of patients:There was no significant difference in HR between the groups at T₁time point（P>0.05）,while at T₂,T₃,T₄,and T₅time points,there was a significant difference in HR（F=3.376,P=0.01<0.05）,of which at T₂time point,the HR of the D1 and D2 groups was significantly lower than that of the S group,and there was no significant difference in the HR between the D1 and D2 groups.At T₃time point,the HR of D1,D2,and D3 groups was significantly lower than that of S group,and there was no significant difference in HR among D1,D2,and D3 groups.At T₄time point,the HR of D4 group was significantly lower than that of S group,and there was no significant difference in HR among the D1,D2,D3,and S groups.At T₅time point,there was no significant difference in HR between the groups.Comparison of the incidence of POD in five groups of patients:None of the subjects in this study had preoperative delirium.There was a statistically significant difference in the incidence of POD among the five groups of patients（χ²=19.329,P=0.001<0.05）.The incidence of POD in the S group was significantly higher than that in the D1,D2,D3 and D4 groups,while there was no significant difference in the incidence of POD among D1,D2,D3 and D4 groups.Comparison of postoperative adverse reactions among five groups of patients:The incidence of postoperative nausea,vomiting and respiratory depression in D1,D2,D3,and D4 groups was significantly lower than that in S group（P<0.001）,and there was no significant difference in postoperative adverse reactions between D1,D2,D3,and D4 groups.Comparison of NRS scores of five groups of patients within three days after operation:The NRS scores of the five groups of patients decreased over time within 3days after surgery（P<0.001）,while there was no significant difference in the NRS scores of each group at T₆,T₇,and T₈time points（P>0.05）.Conclusion:This study found that intravenous infusion of a loading dose of Dex when entering the operating room or during tracheal intubation can reduce the incidence of POD and postoperative adverse reactions in elderly patients undergoing elective laparoscopic radical resection of colorectal cancer,reduce the dosage of intravenous general anesthesia and opioid analgesics during surgery,and have less impact on blood pressure and heart rate.