The Effect Of Using Low-dose Dexmedetomtdine During Tracheal Extubation For Patients With Hypertension After General Anesthesia

Objective: The purpose of this article was to study the effect of usinglow-dose of dexmedetomidine on stress response, extubation time andafter-extubation situation during tracheal extubation in patients withhypertension recovering from general anesthesia extubation period.Methods: Sixty patients with hypertension, ASA II—Ⅲ, scheduled for thelower-extremity surgery under general anesthesia, were participated in one ofthe three randomized trials:1Control Group （Group C, n=20, NS Group） and2Observation Groups （Group D₁: dexmedetomidine0.25μg/kg and Group D₂:dexmedetomidine0.5μg/kg）. For preoperative preparation, all patients werestopped eating12hours and drinking4hours before surgery and were notallowed to take any preoperative medicine. All patients received continuousmonitoring of BP and Bispectral index to detect the depth of anesthesia. Apreoperative infusion of Penehyclidine hydrochloride1mg was used forinduction of anesthesia30m before operation. After the induction of anesthesia,endotracheal intubation was performed and patients were given N20:02（1:1）and1%—3%sevoflurane to maintain deep anesthesia, keep BIS between40and60.30minutes before the end of surgery, patients in Group D₁, Group D₂and Group C were infused dexmedetomidine0.25μg/kg, dexmedetomidine0.25μg/kg and the same volume of normal saline, respectively, within10minutes. All the indicators closely monitored and recorded included: SBP, DBP,HR and MCO at every time-point, such as T₀(（preanesthesia）,T₁（pre-extubation）, T₂（extubation time）, T₃（3min after extubation）, T₄（5minafter extubation） and T₅（10min after extubation） and continuous monitoring BIS. Time periods of experiment were recorded as follow: t₁（time between theend of surgery to extubation）, recovery time t₂（the time after extubation untilpatients could manage instructional activity）. Post treatment of reverse reactioncaused by extubation was also closely recorded.Results:1.There was no statistic difference in quantity, age, gender ratio,weight, time of surgery and time of anesthesia （P>0.05）.2. Haemodynamicindexes such as SBP, DBP, HR and MCO:①SBP and DBP: There was nosignificant difference between the three groups at T0（P＞0.05）.②SBP andDBP in Group D₁and Group D₂were significantly lower than that of Group Cat T₂and T₃, and there was significant difference between data of Group D₂andGroup C （P＜0.05）.③In Group C and Group D₁, SBP and DBP at T₂and T₃were significantly higher than that data at T0respectively.（P＜0.05）④BP andDBP in Group D₂did not change greatly from T₁-T₅than that at T0, on theother hand, there was great difference between Group C and GroupD₁.3.Extuvation time t₁and recovery time t₂：Compared with Group C, t₁and t₂in Group D₁and Group D₂were a little longer, but there was no significantstatistic difference.（P＞0.05）4.Comparison of reverse reaction of extubation：the patients with reverse reaction in Group D₁and Group D₂were much fewerthan that in Group C, there was a signifficant difference between the twoexperimental groups and control group.（P＜0.05） On the other hand, GroupD₂had fewer reverse reactions than that of Group D₁, there was also asignificant difference between Group D₁and Group D₂.（P＜0.05）Conclusion:1.Application of infusion of0.25μg/kg dexmedetomidine or0.5μg/kg dexmedetomidine into patients with hypertension recovering fromgeneral anesthesia extubation period at a single time can significantly reducethe stimulation induced by suction, extubation and incision pain, to produceeffect of sedation and analgesia.2. Stabilize the Hemodynamic index, reduce other reverse reaction and not to prolong the extuabtion time and recovery time.3.With0.5μg/kg dexmedetomidine having a better effect.