Effects Of Dexmedetomidine On QT Interval During Extubation Stage

QT interval is the time from the beginning of QRS-wave to the end of T-wave, which represents the period from ventricular depolarization to repolarization. Every risk factors of QT interval can induct the TDP, which has evoked wide attention. Reviewing the experiement here is to observe the effect of dexmedetomidine hydrochloride to the heart rate, respiratory rate, systolic blood pressure and electrolytes in extubation period in patients of general anesthesia extubation period, which evaluates the effects of dexmedetomidine to hemodynamic in general anesthesia、untoward reaction and provides the guidance for clinical practice.Select intravenous and inhalation anesthesia in patients undergoing elective surgery under the80cases, male, ASA Ⅰ～11, aged18to65years; weight57.9±7.7kg. Country group A was0.9%NaCl and test group B was dexmedetomidine0.4μg·kg-1h-1. Anesthesia induction:All patients were given any premedicant. Anesthesia was indued with midazolam0.05mg·kg-1, propofol2mg·kg-1fentanyl2μg·kg and vecuronium0.1mg·kg-1, intermittent intravenous propofol0.05mg· kg-1min-1and remifentanil0.2g·mg min-1to maintain anesthesia, inhalation of lto2%is oflurane until skin closure, patients didn’t use antiemetic drugs and wihtin the30min of the out of surgery no use of muscle relaxants and analgesics, patents were transferred to PACU by the end of surgery. The PACU patients were randomly divided into2groups:control group,0.9%NaCl (A group) and test group(B group),40cases in each group. A group was given target-controlled infusion of0.9%NACL, B group was given a loading dose0.4μg·kg-h-1by slow intravenous injection pump, the maintenance dose were0.4jμg·kg-1h-1; patients resumed spontaneous breathing was discontinued. Each blood pressure(BP), heart rate(HR), pulse oxygen saturation(SpO2), cardiac(ECG), end-tidal carbon dioxide partial pressure(PetCO2), end-expiratory anesthetic concentration. urine volume, body temperature, blood gas analysis is routine monitoring. Patients were transferred to PACU with ventilator control ventilation, tidal volume8-10ml·kg-1, respiratory rate10to12times·min-1, maintained PETCO2at35-45mmHg. Extubation in patients with indication for extubation is to meet standard from the room to switch out the PACU. SBP, DBP, HR, K+and Ca2+of patients were drawn from following5time points:given a dexmedetomidine or0.9%NaCl solution at instantly (T1), lmin after administer (T2),1min,5min, l0min after extubation (T3,T4,T5). Extubation in patients spontaneous breathing recovery time, call time to eye opening, extubation time and PACU stay were recorded. Respiratory depression, hypertension, tachycardia and bradycardia was observed. Follow-up observation of the project and measures:①The general condition of the patient;②Vital signs, including blood pressure(BP), heart rate(HR), pulse oxygen saturation(SpO2), respiratory rate(RR);③The changes of hemodynamic between being given a dexmedetomidine or0.9%NaCl solution at instantly and10min after extubation,including electrocardiogram(MAP), heartrate(HR), pulse oxygen saturation(SpO2), respiratory rate(RR);④Adverse reactions during extubation period;⑤Electrolytic during extubation period.Results:There was no significance of the two groups of patients in age, weight, operative time (P>0.05).①Changes of QT interval:There was not significant difference of QTC between two groups in T1and T2.QT interval was significantly longer at T3-5in group A than group B. QT interval was significantly longer at T3-5in group A. There were no significant differences in QT interval and QT interval dispersion at each time point in group B.②Changes of MAP and HR:There was not significant difference of MAP and HR between two groups in T1and T2.Those in T3-T5were heighten than the basic value(T1). There was not statistical significance inner; Contract two groups of extubation MAP and HR, the control group(group B) hemodynamic changes greatly between pre-extubation and after extubation while the experimental groups(group A) changes was no significant, there was significant difference in control group between pre-extubation period and after extubation period.③Blood sample were detected during extubation stage for determination of plasma levels of K+and Ca2+.④Adverse reactions of two groups during tracheal extubation period,the experimental group of agitation and pain was less than the control group, there is significant difference between two groups. The experimental group in respiratory depression, nausea, vomiting, bucking and shivering was less than the control group.Conclusion:①0.4μg· kg-1h-1of DEX sedation moderate, stable hemodynamic, fewer complications, does not affect the recovery time,more suitable for estuation anesthesia application;②Dexmedetomidine can effectively inhibite the prolongation of QT interval but no significant difference of K+and Ca2+;③Dexmedetomidine can effectively inhibite the prolongation of QT interval.