Impacts Of Remote Ischemic Preconditioning On Early-stage Postoperative Cognitive Function Among Elder Patients

ObjectiveThis study aimed to investigate the impacts of remote ischemic preconditioning on the elderly,and to testify whether or not RIPC was a practical non-invasive protocol for improving postoperative cognitive function of elder patients.MethodsThis research included 69 elder patients（age≥60y）who were scheduled for selective surgeries in Tianjin medical university general hospital during January 10^th2018 to November 20^th 2019.Thirty patients were randomly divided into remote ischemic preconditioning group（R group）,and twenty-nine patients were randomly assigned to control group（C group）.Both R group and C group went through total intravenous anesthesia.Bispectral index of each patient was monitored and maintained at 40-60.After anesthesia induction and trachea intubation,patients in R group received3 cycles ischemic preconditioning on their right upper arm,which lasted 3min per cycle with 5min intervals.RIPC was conducted by inflating orthopedic tourniquet to30mm Hg above basal systolic pressure maximum to 200mm Hg.Meanwhile,researcher placed tourniquet on C group at same time and same arm without inflation.Every patient took mini-mental state examination（MMSE）,number connecting test（NCT）,picture recall test（PRT）,digit-symbol test（DST）,Stroop the color test（Stroop test）,numerical symbol conversion test（DSST）the day before surgery and eight days after surgery to evaluate perioperative cognitive function.Then,investigator contrasted postoperative scores to preoperative scores of every test in two groups,as well as comparing preoperative scores or postoperative scores between two groups.Z scores of each test were calculated using twenty normal nonsurgical person performances to reduce learning effect.Total Z score was the mean of Z scores of all tests.Patients with two Z scores including total Z score that were lager than or equal to1.96 was considered as postoperative early cognitive dysfunction.ResultsThe statistics of tests results was processed by SPSS26.0.Measurement data was presented as average±standard deviation and analyzed by independent-sample t test,while enumeration data was analyzed by Chi square test.P value less than or equal to0.05 was considered as statistical difference.Statistical results showed that no significant difference existed between two groups in gender,age,body mass index,underlying disease,type of surgeries,blood loss,operation time,anesthesia time,incubation time,anaesthetic drugs consumption（p>0.05）.There was no significant difference in preoperative scores of neuropsychological tests between two groups（p>0.05）.Apart from Stroop test C,all tests’results did not reveal significant difference in group comparison or vertical comparison of the time dimension.At eighth day after surgery,R group performed better than C group in Stroop test C（p=0.035）,and postoperative scores of R group significantly improved comparing to preoperative scores（p=0.046）.According to calculation results of Z scores and total Z scores,nine patients exhibited postoperative early cognitive dysfunction in C group,while two patients in R group（p=0.043）.Last but not the least,none RIPC relative adverse reaction was reported in two groups during entire follow-up.ConclusionBased on experimental results,RIPC could safely reduce incidence of postoperative early cognitive dysfunction in elder patients.These results also implied the prospect of RIPC becoming a practical prevention for postoperative early cognitive dysfunction among the elderly.