Intravenous Anesthesia Versus Intravenous Inhalational Anesthesia Effects On Postoperative Cognition In Elderly Patients Undergoing Laparoscopic Intestinal Surgery

Objective:Most procedures require general anesthesia,with sevoflurane and propofol being the most commonly used inhalation and intravenous anesthetics.According to biophysical and animal model studies,low doses of inhaled anesthetics do promote Aβoligomerization.High concentrations of propofol also oligomeric Aβ.And dense extracellular plaques composed of oligomeric fibulles of beta-amyloid peptide and insoluble polymers of phosphorylated tubulin（tau）are found in large numbers in patients with cognitive impairment and Alzheimer’s disease.Therefore,it is important to investigate whether propofol,which is widely used at clinically relevant concentrations,has any effect on Aβoligomerization,resulting in brain damage and cognitive impairment.In such systematic studies of propofo-Aβinteractions,it is also important to investigate whether the combination of propofol（at clinically relevant concentrations）with lower doses of anesthetics（e.g.,sevoflurane）promotes Aβoligopoly and thus postoperative cognitive impairment.The purpose of this study was to investigate whether propofol alone and sevoflurane combined administration of medium anesthetic propofol have a difference in postoperative neurocognitive outcomes in elderly patients undergoing laparoscopic intestinal surgery.Methods:Selected patients underwent laparoscopic intestinal surgery under general anesthesia in our institution.Individuals with BMIs between 19 and 30 kg/m2,ASA grades Ⅰ or Ⅱ,and age 60 to 75.The patients were split into two groups using a random number table method.One day prior to surgery,the patients had evaluations using Mini-mental state Examination,The Boston Naming Test（Chinese version of BNT-30）,Digital span test（DST）,Symbol Digit Modalities Test,and the clock drawing test.Patients with MMSE preoperative scores（illiterate≤17 points,primary school≤20 points,junior high school and above≤24 points）were excluded,and other patients were enrolled.In addition,the patients underwent The Boston Naming Test（Chinese version of BNT-30）,Digital span test（DST）,Symbol Digit Modalities Test,and the clock drawing test at 3 and 30 days following surgery.The preoperative comparison was then done for statistical analysis.As a control group,60 participants were chosen at random from the identical inclusion criteria as the experimental group,with the exception of those who did not have surgery.groups were created for intravenous anesthesia,intravenous absorption complex,and control.Routine induction was carried out,and sufentanil 0.4ug/kg,propofol 2mg/kg,and cisatracurium 0.2mg/kg were administered intravenously.Group D1:Remifentanil（0.1-0.5ug/kg/min）and propofol（4-8mg/（kg·h））intravenous pumps are used to maintain anesthesia;D2 group:Intravenous aspiration combined group anesthetic maintenance with sevoflurane（1%～1.5%）,propofol（2～4mg/（kg·h））,and remifentanil（0.1～0.5ug/kg/min）intravenous infusions;Group P:control group;follow-up operations were not conducted on this group.After endotracheal intubation,mechanical breathing was carried out(VT 8～10 ml/kg,RR 8～12 times/min,I:E:1:1.5,oxygen flow 2L/min,control P_ETCO₂30～40mm Hg).Nasopharyngeal temperature was maintained at 36～37.2°C,and intraoperative blood pressure was kept at 30%of baseline.By modifying the dosages of propofol,sevoflurane,and remifentanil,BIS was kept between 45 and 55.The right dosage of cisatracurium and vasoactive medications（ephedrine and m-hydroxyamine for pressors;Atropine for heart rate increase）.For postoperative analgesia,sufentanil 0.15ug/kg was added 40 minutes before to surgery.Up until the patient was released from the hospital,adverse events were documented both during and after operation.Analgesic pump for postoperative pain management（Sufentanil:2～3 times body weight）.Dexmedetomidine,hormones,non-steroidal anti-inflammatory medications,and long-acting sedatives should not be used during or after surgery.General information about the patients in the three groups was recorded,statistically analyzed,and compared,including the length of the procedure,heart rate,oxygen saturation,and noninvasive mean blood pressure recorded before anesthesia（T0）,15 minutes after endotracheal intubation（T1）,1 hour after the procedure（T2）,at the conclusion of the procedure（T3）,and 24 hours after the procedure（T4）.Recorded adverse reactions included postoperative nausea and vomiting as well as the awake extubation time.Following surgery,the RASS and CAM-ICU scores were reported.At the third and thirty-day postoperative follow-ups,the results of four scales,comprising The Boston Naming Test（Chinese version of BNT-30）,Digital span test（DST）,Symbol Digit Modalities Test,and the clock drawing test,were recorded.Z-score approach was used to analyze the score findings to identify delayed neurocognitive recovery（DNR）.Results:The study included 86 patients in total.Six of them didn’t match the requirements for inclusion.80 subjects in all were eventually included.Six patients who were included in the study were not given the prescribed intervention（5 had their surgeries altered to open surgery,and 1 withdrew consent to participate）;two lost follow-up;and two were omitted because they were given medicines that should not have been given.In line with the protocol,35 patients in the D1 group under intravenous anesthesia and 35 patients in the D2 group receiving intravenous aspiration completed the study.A clinically significant decline in at least two of the four test scale characteristics（Z<-1.96）relative to preoperative values was used to determine postoperative cognitive impairment.The incidence of delayed neurocognitive recovery（DNR）was 0 in the intravenous anesthetic group on day 3 after surgery and2.9%on day 30 after surgery（n=35）in that group.On the third postoperative day（n=35）,the frequency of delayed neurocognitive recovery（DNR）was 2.9%;by the30th postoperative day（n=35）,it had dropped to 8.6%.Across the two groups,there were no differences in the incidence of delayed neurocognitive recovery（DNR）.In addition,the test parameters were lower after surgery for the two groups in terms of attention,working memory,motor speed-executive ability,and visual space,and the difference was statistically significant（P<0.05）.Speech in the intravenous anesthetic group was largely impaired on day 30 following surgery,but did not differ significantly from day 3 before to surgery.However,the static inhalation group’s reduced speech skills first surfaced shortly after the operation and only fully recovered on day 30.There was no difference in the strength of the two forms of anesthesia’s effects,and there was no connection between postoperative delirium and delayed neurocognitive recovery（DNR）.Compared with the combination of intravenous anesthesia,patients with simple intravenous anesthesia had shorter waking extubation time and a lower incidence of postoperative nausea and vomiting,but it had a greater effect on intraoperative hemodynamics（P<0.05）.Conclusion:Both types of anesthesia had an effect on postoperative cognition,and there was no difference in the incidence of delayed neurocognitive recovery（DNR）between the two groups.