The Application Of Dexmedetomidine During Tracheal Extubation After General Anesthesia In Hypertensive Patients

Objective: To investigate the effectiveness of using different dose de-xmedetomindine in maintaining hemodynamic stability,plasma catecholamin-e concentrations,sedation and analgesia during tracheal extubation after ge-neral anesthesia in hypertensive patients. Provide clinical evidence for hyp-ertensive patients during the period of tracheal extubation.Methods: Thirtypatients,AsA Ⅰ～Ⅱ, Hypertension clinical stageⅠ～Ⅱ， scheduled forabdominal surgery, were randomly assigned into three group（n=10each）:theNS group（control group） and dexmedetomidine0.5μg.kg^-1dose group, dex-medetomidine0.3μg·kg^-1dose group.A randomized,double blind Control trialwas used in this study. All patients were fasted12h,forbidden to drink8h.All patients received a preoperative infusion of Ringer’s lactate soluti-on with the rate of10¹5ml·kg^-1·h^-1and continuous monitoring the BP,HR,Sp02.Fentany3μg·kg^-1,midazolam0.05mg·kg^-1,propofol1.5²mg·kg^-1and rocuronium0.6mg·kg^-1was used for induction of anesthesia. Endot-racheal intubation was performed after drug onset and then intermittent p-ositive pressure ventilation mode was used.Remifentanil0.1¹.5μg·kg^-1·min^-1atracurium5¹0μg·kg^-1·min^-1and2³%sevflurane were used to maintainanesthesia during the operations. All patients received continuous monit-oring of BIS and MAC．Atracurium was stopped and sevoflurane and remifentanil were reduced before the end of surgery about30min. At10min before the end of surgery,we started to infuse dexmedetomidine orthe same volume of saline（control group）using microcomputer pump.Atthe end of surgery,sevoflurane and remifentanil were stopped immed-iately and neostigmine1mg and atropine0.5mg were injected intraven-ously.The extubation was performed when BIS>85and Spo2>95%whenthe patients breathing air.All patients were Send to PACU. All monitoringindicators include:1.Recorded the Value of SBP,DBP,HR,SPO₂, MAC at T0（preanesthesia）,Tl（before injecting experemental drugs）,T₂（5min after injecti-ng experemental drugs）,T₃（10min after injecting experemental drugs）,T₄（bef-ore extubation）,T₅（1min after extubation）,T₆（5min after extubation）,T₇（10minafter extubation）,T₈（15min after extubation）, T₉（20min after extubation）,T₁0（25min after extubation）,T₁₁（30min after extubation）.2.Determined plasma c-atecholamine concentrations using cubital vein blood at T₁,T₂,T₆.3. Recor-ded OAA/S sedation score and VDS5painscore at T₆,T₇,T₈,T₉,T₁0,T₁₁.Res-ults:1.Hemodynamic changes: Comparison among groups:1) SBP:0.5μg.kg^-1dose group at T₂～T₁₁,0.3μg.kg^-1dose group at T₅～T₁₁were lower thancontrol group（p＜0.05）.0.5μg.kg^-1dose group were lower than0.3μg.kg^-1dose group at T₄, T₆～T₁₁（p＜0.05）.2) DBP:0.5μg.kg^-1dose group atT^-12～T₁₁,0.3μg.kgdose group at T₄～T₁₁were lower than control group（p＜0.05）.0.5μg.kg^-1dose group at T₅～T₁₁were lower than0.3μg.kg^-1dosegroup（p＜0.05）.3)HR:0.5μg.kg^-1dose group at T₁3～T₁₁,0.3μg.kg-dose gr- oup at T₂～T₁1were lower than control group（p＜0.05）.0.5μg.kg^-1dose gr-oup at T₃～T₁1were lower than0.3μg.kg^-1dosegroup（p＜0.05）. Comparisongroup:1)SBP:0.5μg.kg^-1dose group at T₁～T4,T6～T₁1,0.3μg.kg^-1dose grou-p at T₁～T₃,T7～T₁1were lower than T0（p＜0.05）. Control group at T₁～T₃was lower than T0,at T5,T6were higher thanT0（p＜0.05）.2)DBP:0.5μg.kg^-1dose group at T₁～T₁1,0.3μg.kg^-1dose group at T₁～T₃,T7～T₁1were lowerthan T0（p＜0.05）. Control group at T₁,T₂,T₁0were lower than T0,at T5washigher than T0（p＜0.05）.3) HR:0.5μg.kg^-1d-ose group at T₁～T₃,T6～T₁1,0.3μg.kg^-1dose group at T₁～T₃,T9,T₁1was lo-wer than T0（p＜0.05）.Control g-roup at T4～T7were higher than T0（p＜0.05）.2.Plasma catecholamine conc-entrations:1)There was no difference amonggroups at T₁.2) The plasma cat-echolamine concentrations of0.5μg.kg^-1dose group was lower than controlgroup at T₂and T6,but there was no difference between0.3μg.kg^-1dose g-roup and control group at the same time.T₁～T₃,T7～T₁1was lower than T0（p＜0.05）.3) The plasma epinephrine anddopamine concentrations of0.5μg.kg^-1dose group at T6, plasma norepinep-hrine concentrations at T₂,T6were lower than0.3μg.kg^-1dose group（p＜0.05）.4) The plasma epinephr-ine and norepinephrine concentrations of0.5μg.kg^-1dose group at T₂, werelower than T₁（p＜0.05）. The plasma norepin-ephrine concentrations of thisgroup at T6was higher than T₂（p＜0.05）,butthere was no difference of ep-inephrine concentrations at the same time（p＞0.05）.5) But there was no di-fference of plasma epinephrine and norepinephrine concentrations in 0.3μg.kg^-1dose group and control group at T₂andT1. Plasma epinephrineand norepinephrine concentrations of0.3μg.kg^-1dosegroup and control groupat T6were higher than that at T₂.3.OAA/S seda-tion score:0.5μg.kg^-1dosegroup were significantly lower than controI group at T₇～T₁₁（p＜0.05） an-d significantly lower than0.3μg.kg^-1dose gr-oup at T₇、T8、T10.there wasno difference between0.3μg.kg^-1dose groupand control group（p＞0.05）.4.VDS5pain score:0.5μg.kg^-1dose group at T16～T₁₁and0.3μg.kg-dosegroup at T₇～T₁₁were significantly lower than controI group control.0.5μg.kg^-1dose group were significantly lower than0.3μg.kg^-1dose group atT₇～T₁₁.Conclusion:1.Application of0.5μg.kg^-1d-ose dexmedetomidine cansignificantly reduce the increased of BP and HRfor extubation stimulationof general anesthesia and can significantly inhibit the releasing of epineph-rine and norepinephrine.2. Application of0.3μg.kg^-1dose dexmedetomidinecan significantly reduce the increased of BP andHR for extubation stimula-tion of general anesthesia,but couldn’t significantly inhibit the releasing ofepinephrine and norepinephrine.3. Dexmedetomidine has sedative and anal-gesic effect,without delayed recovery. The sedativeand analgesic effect of0.5μg.kg^-1dose dexmedetomidine was well than0.3μg.kg^-1dose.