Effect Of Dexmedetomidine On Post-operative Cognitive Dysfunction In Elderly Patients With Abdominal Surgery

Objective:To investigate the effect of dexmedetomidine on postoperativecognitive function in elderly patients in abdominal surgery with generalanesthesia and to provide a certain theoretical basis for future research onpostoperative cognitive function.Methods: Eighty patients scheduled for abdominal operation（30casesfor gastrointestinal operation,20cases for biliary operation,30cases forgynecologic operation）,ASA II～Ⅲ,aged60to75,BMI20²9kg/m², surgerytime2-4h,were selected. Ruling out standard:1. Diabetes or hypertensionabove â…  level2.Preoperative cognitive dysfunction or recognized factors thataffect cognitive function3.Preoperatively taking psychoactive substancesalcohol and drug abuse4.Water, electrolyte and acid-base balance disorders5.History of heart block or sinus bradycardia; cardiac function above II6.Unable to communicate and postoperative follow-up can not becompleted.The patients were randomly divided into dexmedetomidine given0.5μg· kg^-1· h^-1group （group D,n=40） and normal saline group （group S,n=40）.Preoperative nothing-by-mouth for6⁸h,no premedication.Afterentrance into the operating room,the patient was routinely monitored of theelectrocardiogram （ECG）, blood pressure （NBP）, pulse oximetry （SpO₂）,end-tidal partial pressure of carbon dioxide （PetCO₂）and anesthetic depth withNarcotrend-Compactt monitor,open a peripheral vein, infuse sodium lactateRinger’s solution.Endotracheal general anesthesia, oxygen was given withmask at6L/min.The period of anesthesia induction infuse hydroxyethyl starch5ml/kg. Anesthesia induction drugs are used intravenously, midazolam0.05mg/kg, cis-atracurium0.15mg/kg,sufentanil0.3μg/kg,etomidate0.15⁰.3mg/kg, followed by endotracheal intubation and volume controlventilation with anesthesia machine,during operation remifentanil0.05 ⁰.3μg· kg^-1· min-1, propofol2⁶mg· kg^-1· h^-1, sevoflurane1%²%were administered to maintain anesthesia, in dexmedetomidine group（group D）dexmedetomidine was continuously intravenous infused at0.5μg· kg^-1· h^-1until half an hour before the end of surgery, in normal saline group（group S）dexmedetomidine was replaced with0.9%sodium chloride solution. Fluidinfusion rate was adjusted according to bleeding; propofol was adjusted tomaintain the Narcotrend Index （NTI） at37⁶4;remifentanil rate was adjustedaccording to the blood pressure and heart rate.And timely intermittent addcisatracurium besylate to maintain muscle relaxants requirements.Keep SpO₂more than98%and PetCO₂35⁴5mmHg. If BP<20ï¼…baseline，giveephedrine3mgï¼›BP>20ï¼…baseline，give urapidil25mgï¼›HR<50bpm／min,giveatropine0.5mg. Dexmedetomidine was stopped at30min before the end ofsurgery, sevoflurane inhalation and remifentanil were stopped at the beginningof surgical skin closure, propofol was stopped after the end of surgery.The following were observed and recorded in two groups ofpatients:1.Surgery time,anesthesia time,drug use in the surgery.2.Spontaneous breathing recovery time, postoperative eye opening time,extubation time.3. The2day before surgery and postoperative2and7day,the mini-mental score method MMSE scale was used for functional testing ofneuropsychiatric patients.4. There were5time points, is,baseline beforeanesthesia （T₀）,10min after intubation （T₁）,30min after operation（T₂）, endof surgery （T₃）, postoperative2h （T₄）,postoperative1day（T₅） at each timepoint the systolic blood pressuremean（SBP）,the mean arterial pressure （MAP）and heart rate （HR）, were recorded respectively, and samples of venous bloodserum were extracted at each time point for measuring cortisol （Cort）,interleukin （IL）-6, S-100β protein by ELISA.5. Untoward effects were alsoobserved after operation.Both of the two groups used patient controlled intravenous analgesia.Results: There was no significant difference among the age, weight, sex,years of education, ASA physical status, preoperative complications, surgerytime, anesthesia time, and out of volume （p>0.05）. Dose of propofol and remifentanil in group D was significantly less than that in group S, there weresignificant difference（p <0.05）. Atropine application number of cases inGroup D were more than group S, there were significant difference （p<0.05）,There were not significantly different in ephedrine and urapidil （p>0.05）.There was no statistically significant difference in spontaneous breathingrecovery time, wake-up time to eye opening and extubation time of bothgroups （p>0.05）.1day and3day POCD incidence in group S（30%,22.5%）were higher than that in group D （10%,2.5%）, There was statisticallysignificant difference（p <0.05）. There was statistically significant differencebetween and in the two groups of HR （p<0.05）. Two groups with T₂and T₃were significant difference （p <0.05） from T₀. Group D significantly lowerand group S was significantly higher.More significant difference （p <0.05） inMAP between the two groups, both groups have a significantly higher at T₂.There was statistically significant difference from T₀（p <0.05）. Group D at T₅down to the preoperation.But Group S does not. There was statisticallysignificant at the SBP between the groups （p<0.05）, both of them in SBP at T₁reduce, statistically significant differences from T₀（p<0.05）.But group Dwas more stability than group S. There was statistically significant differenceat IL-6between the two groups （p <0.05）.IL-6of group S was significantlyhigher in T₃and T₄（p <0.05）. IL-6of group D at T₃increased, at T₄beganto fall down,at T₅down to the preoperative levels. Difference of S-100β andCort concentration between and in the two groups was statistically significant（p<0.05）. S-100β and Cort concentration in the both groups began to declineat T₂increased, at T₄began to fall down, however, that in group D was lowerthan in group S.There was no intubation cough and respiratory depression,postoperative irritability, pain, nausea and vomit, and intraoperative awarenessin both groups.Conclusions:1Dexmedetomidine venous infusion at0.5ug· kg^-1· h^-1 in the elderlyabdominal surgery under combined intravenous-inhalational anesthesia cansave the dose of propofol and remifentanil medication. 2Although HR was some lower, but in general it is helpful to obtain moresatisfactory hemodynamic parameters.3Dexmedetomidine may reduce stress response and S-100β proteinconcentrations in the elderly patients with POCD incidence reduced.