Intraperitoneal insufflation of carbon dioxide may affect the sympathetic activity that leads to changes in ventricular repolarization. This in turn can result in changes of heart rate-corrected QT (QTc) interval and Tpeak-Tend (Tp-e) interval. Dexmedetomidine is a highly selective a2-receptor agonist and has potential antiarrhythmic properties. This prospective, randomized, double-blinded, controlled study evaluated the effects of dexmedetomidine administration on QTc and Tp-e intervals during robot-assisted laparoscopic prostatectomy with steep Trendelenburg position. Fifty patients scheduled for robot-assisted laparoscopic prostatectomy randomly received either a continuous infusion of dexmedetomidine at a rate of 0.3mg/kg/hour, from anesthetic induction until the end of the Trendelenburg position (dexmedetomidine group; n=25), or the same volume of normal saline (control group; n=25). Anesthesia was maintained with sevoflurane and remifentanil. The primary and secondary goalswere to evaluate the effect of dexmedetomidine on theQTc and Tp-e interval changes. Mean arterial pressure, heart rate, end-tidal CO2, and end-tidal sevoflurane concentrations were assessed as well. Forty-seven patients (94%) completed the study. Dexmedetomidine significantly attenuated QTc interval prolongation and reduced the Tp-e interval, even though the baseline values of the QTc and Tp-e intervals were similar between the 2 groups (PGroup ± Time=0.001 and 0.014, respectively). Twenty-two patients (96%) in the control group and 13 (54%) in the dexmedetomidine group had QTc interval prolongation of >20ms from the baseline value during surgery (P=0.001). The maximum QTc interval prolongation from the baseline value during surgery was 46±21ms in the control group and 24±21ms in the dexmedetomidine group (mean±SD, P=0.001). Mean arterial pressure and heart rate were comparable between the groups. Continuous infusion of dexmedetomidine at a rate of 0.3mg/kg/hour significantly attenuated the QTc interval prolongation induced by CO2 pneumoperitoneum with steep Trendelenburg position. Furthermore, dexmedetomidine reduced the Tp-e interval. Thus, dexmedetomidine administration may be effective for patients who are susceptible to the development of ventricular arrhythmia during robot-assisted laparoscopic prostatectomy.
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