| BackgroundClinically ideal sedation medicines are required not only to show satisfactorysedating effects, but also to have good anterograde amnesia effects. The effect ofanesthesia and sedation can ease the nervous and anxious emotion of patients andmake them cooperate with the operation positively, which is a basic premise for thesuccess of the operation; Anterograde amnesia is the important guarantee ofeliminating patient’s fear, preventing intraoperative awareness and lowering theoccurrence rate of postoperative mental and intelligent retardation. Propofol not onlyhas the functions of calming and forgetting, but also has the features of quick effect,short lasting time and quick wake up without phenomenon of drug accumulation,which is a fairly ideal anesthesia drug. It has been widely used for induction andmaintenance of anesthesia, sedation of ICU patients and so on. The study has foundthat propofol’s role of forgetting is positively correlated with its dose. As propofol oflow concentration only inhibits part of explicit memory, when the dose of propofolhas been increased to the perfect clinically narcotism, the memory function ofpatients is not inhibited entirely so that their brains are still dealing with auralinformation. If we continue to increase dosage, the drug will have obvious inhibitionof respiratory cycle and intraoperative awareness still occurs, thus satisfactoryamnesia effect is not achieved.Dexmedetomidine is a highly selective α2-adrenergic receptor agonist withconsiderable sedation and anti-anxiety effects. However, the drug target of calmhypnosis function produced by dexmedetomidine is different from propofol, forpropofol works on the sedation and hypnosis generated from cerebral cortex, whiledexmedetomidine exerts that function from affecting locus coeruleus besides thefourth ventricle. Meanwhile dexmedetomidine also has the effect of analgesia,sedation, anti-anxiety and antisialic, which can obviously reduce the dosage ofpropofol when be used with propofol and is often used as adjuvants in general anesthesia. Hall et al. have found that dexmedetomidine has the effect of anterogradeamnesia. At present, there is no research confirming that dexmedetomidine couldenhance the amnesia effect of propofol.For a long time, the evaluation standard of the sedation and anesthesia degreeof patients during surgeries has only been decided by direct clinical experience. Withthe application of computers in medical field, the Bispectral Index (BIS), which isone of the world-recognized anesthesia and sedation depth mornitoring indexes atpresent, has gradually been applied in clinical anesthesia. It can preferably reflect thefunction status and changes of cerebral cortex so as to judge the depressed state ofpatient’s brain. The advent of bispectral index has improved the quality of operativeanesthesia and ICU treatment, making the assessment of patient’s anesthesia andsedation more objective and accurate. Lots of domestic and foreign scholars haveapplied BIS to study the sedation effect of propofol. However, the anterogradeamnesic effects of dexmedetomidine combined with propofol are still debatable.PurposeThis experiment would provide basis for the fair use of anesthetic and sedativein clinical cases as well as the adoption of reasonable sedation depth through studyingthe effects of different doses of dexmedetomidine on the anterograde amnesia effectand sedative effect of propofol.Material and methodSelect60patients undergoing elective gynecological operations, age from20to50, ASA grading fromⅠto Ⅱ with no dysmnesia, no central nervous system diseaseand no recent psychiatric medication. Divide them into Group Dexmedetomidine0.2μg·kg-1(Group D1), Group Dexmedetomidine0.4μg·kg-1(Group D2) and ControlGroup (Group C) randomly. Patients will be fasting for solids and liquids, and nopremedication. After entering the operating room, venous channel of patients will be opened. Their mean arterial pressure (MAP), heart rate (HR), pulse oxygen saturation(SpO2) and bispectral index and state (BIS) should be monitored. The patients inGroup D1and Group D2were injected with Dexmedetomidine in15min at aconcentration of0.2μg·kg-1and0.4μg·kg-1respectively. Group C was the blankcontrol. Basic values of MAP, HR, SpO2and BIS were recorded after the effects ofthe drug acted. After that, target-controlled infusion of propofol was conducted withthe concentration in plasma as the target concentration. The target concentrationbegan with0.5μg·ml-1, and increased by0.2μg·ml-1for each addition. Observe theinstance state of propofol (initial state) and the value that reach corresponding roomeffects target concentration raise to plasma target concentration comma MAP, HR,SpO2and BIS, and then conduct forgotten test to the patient who is in surgery: tellthe patient to look at a picture, the picture types are different each time, but at onetime patients of different groups look at the same picture, then ask the patient to saythe content of the picture, following up with the patients24H after the surgery, askthem to find the picture that they looked before the surgery, if one can not find it orfind the wrong picture, then define it as forgetting. Meanwhile, conduct OAA/Sgrading and stop progressively increasing when the OAA/S grade of the patientreaches2points. Adopting general anesthesia, for anesthesia induction, adjustingtarget propofol concentration to4.0μg·ml-1. intravenously injecting4μg·kg-1offentanyl and0.15mg·kg-1of cisatracurium benzene sulfonic acid, then adopting rapidsequence endotracheal intubation with propofol and fentanyl as maintenancemedication, intraoperative BIS values being kept between40and60. Stop injectingmedicines5minutes before the operation is done with no use ofwakefulness-promoting medicines and muscle relaxants antagonists. No postoperativeanalgesia using patient controlled analgesia arranged as well.Statistics process: Analyze by statistical software SPSS17.0. If themeasurement data is in accordance with normal distribution, it will be represented bymean±standard deviation. The comparison among groups adopts one-way analysis ofvariance, and the pairwise comparison among groups adopts LSD-t test. AdoptingKruskal-Wallis test to count data. Inspection level is a=0.05. Result1general dataThere is no statistic significance difference of age, weight and anesthesiaduration in the three groups (P>0.05).2Ct, BIS, OAA/S grading, and relationship among anterograde amnesiaPatients of each group have gradually decreased OAA/S score with increased Ct.Compared with group C, D1and D2patients reached on the same degree ofsedation,the decrease of Ct was statistically significant (P<0.05).Patients of eachgroup have gradually increased forgetting rates with increased Ct and decreased BIS.The patients of group D1and D2have greater BIS values than group C when amnesiaoccurs (P<0.05). D2group has a higher BIS value than D1group when anterogradeamnesia happened (P<0.05). In contrast to the BIS value, patients in Group D1andD2have a lower Ct value than that of Group C when forgetting occurs(P<0.05).Compared with D1group, the Ct value reduction of D2group when anterogradeamnesia occurs is more obvious (P<0.05). The difference between Group D1andGroup D2has no statistical significance(P>0.05). Three groups of patients’ forgettingrate gradually increases with the increasing of Ct and decreasing of OAA/S score. Butwhen three groups of patients start anterograde amnesia, there appears no significancedifference(P>0.05)among their scores of OAA/S.Conclusion1Dexmedetomidine can enhance the sedative effect of propofol.2Dexmedetomidine can enhance anterograde amnesia effect of Propofol.3Dexmedetomidine is dose-dependent on potentiation of propofol’s anterogradeamnesia effect.It can not only decrease the Ct of propofol and enhance the sedativeeffect of propofol,but also decrease respiratory depression of propofol when the dose of dexmedetomidine reach0.4μg·kg-1.It is the optimum dose of dexmedetomidine. |
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