Effect Of Rapid Intravenous Injection Of Dexmedetomidine On Hemodynamics During Induction Of General Anesthesia

ObjectiveIn the induction period of general anesthesia,hemodynamics often fluctuates dramatically.Specifically,in the first stage,due to the inhibition of the cardiovascular system by anesthesia drugs,blood pressure drops and heart rate slows down after injection of drugs.In the second stage,due to the operation of endotracheal intubation,the sympathetic nerve is activated,and the secretion of catecholamine increases,which is manifested as the increase of blood pressure and heart rate.Dexmedetomidine has sedative,anti-anxiety and anti-sympathetic effects.Large doses or rapid intravenous injections can cause temporary increase in blood pressure.Based on the unique pharmacologic properties of dexmedetomidine,this study is to investigate the effect of rapid intravenous infusion of loading dose dexmedetomidine on maintaining hemodynamic stability during induction of general anesthesia and to evaluate its clinical safety.MethodA total of 60 patients received elective surgical procedures under tracheal intubation general anesthesia were randomly divided into dexmedetomidine group(DEX group)and normal saline group(NS group)by random number table method,with 30 patients in each group.At the beginning of anaesthesia,patients in the DEX group received intravenous infusion of 0.5ug/kg loading dose of dexmedetomidine(within 2 min)and the patients in the NS group received an equal volume of normal saline(also within 2 min).All patients were preoxygenated and induced with propofol target controlled infusion(TCI),at a target plasma concentration of 3.0 ug/ml using with Marsh parameter model,followed by intravenous infusion of 0.2 mg/kg cisatracurium and 0.5 ug/kg sufentanil.After complete muscle relaxation,endotracheal intubation was performed using a video laryngoscope.Anesthesia was maintained with propofol TCI and remifentanil.According to the changing trend of BIS value,the plasma target concentration of propofol TCI was appropriately adjusted to maintain the BIS value between 40 and 55.The following adverse events occurred during induction be medicated appropriately: heart rate <50 times/min,atropine treatment be given;Heart rate >100 times/min,treated with esmolol;Blood pressure was increased by more than 30% of the baseline and was treated with urapidil;The blood pressure was reduced by more than 30% of the baseline and treated with ephedrine or norepinephrine.The preoperative demographic and time from anesthesia induction to skin cutting were recorded.The following 6 time points were observed: before anesthesia induction(T1),pre-intubation(T2),1min after intubation(T3),3min after intubation(T4),5min after intubation(T5),and at the time before operation(T6).Heart rate(HR),Systolic blood pressure(SBP),diastolic blood pressure(DBP)and BIS value at corresponding time point were recorded.The time from anesthesia induction to loss of consciousness(no response to verbal stimulate)were recorded.The consumption of propofol during induction of general anesthesia was recorded.The occurrence of hemodynamic adverse events in the two groups was recorded.ResultsIntra-group comparison: Compared with T1,HR,SBP and DBP were descread at T2 in the two groups,with statistically significant differences(P < 0.05).Compared with T2,HR,SBP and DBP were increased at T3 in the two groups,with statistically significant differences(P < 0.05).Inter-group comparison: SBP was significantly higher in the DEX group than the NS group at the time points T2,T5 and T6.And at the time points T3 and T4,SBP was significantly lower in the DEX group than the NS group(P < 0.05).DBP in the DEX group was higher than NS group at time T2,and at time T3 and T4,the DEX group was lower than NS group(P < 0.05).There was no significant difference in DBP between the two groups at time T5 and time T6(P > 0.05).The HR of DEX group was significantly slower than NS group at T3,T4 and T6(P < 0.05),while the difference between the two groups was not statistically significant at T2 and T5(P > 0.05).BIS value at T1 in the two groups was not statistically significant(P >.05).BIS value in DEX group was significantly lower than NS group at T2(P < 0.05),and sedation level in two group was consistent at T3-T6.The time for consciousness to loss in DEX group was significantly shorter than NS group,and the consumption of propofol during peri-induction was significantly lower than NS group(P < 0.05).Adverse events: the proportion of hypotension after general anesthesia and post-intubation tachycardia in the NS group was significantly higher than DEX group,and the probability of bradycardia after rapid administration of dexmedetomidine was higher(P < 0.05).ConclusionsRapid intravenous infusion of 0.5ug/kg dexmedetomidine during the period of general anesthesia induction can effectively alleviate the dorp of blood pressure caused by anesthetics and suppress the sympathetic response caused by endotracheal intubation.Dexmedetomidine rapid intravenous infusion has a synergistic effect with propofol,which can increase sedation degree,shorten the time for patients to lose consciousness during anesthesia induction,and reduce propofol dosage in the peri-induction period.In conclusion,rapid intravenous infusion of dexmedetomidine during the induction period can effectively stabilize the hemodynamics during the induction period and is safe and feasible.