Erschienen in:
01.06.2015 | Original Article
A randomized controlled trial of the effect of preoperative dexmedetomidine on the half maximal effective concentration of propofol for successful i-gel insertion without muscle relaxants
verfasst von:
Young-Eun Jang, Yong-Chul Kim, Hyun-Kyu Yoon, Young-Tae Jeon, Jung-Won Hwang, Eugene Kim, Hee-Pyoung Park
Erschienen in:
Journal of Anesthesia
|
Ausgabe 3/2015
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Abstract
Background
Dexmedetomidine is a useful anesthetic adjuvant for general anesthesia. We determined whether preoperative dexmedetomidine administration could reduce the half maximal effective concentration (EC50) of propofol for successful i-gel insertion without muscle relaxants.
Methods
Thirty-seven patients were randomly allocated to one of two groups. In the dexmedetomidine group (n = 19), dexmedetomidine (1 µg/kg) was loaded for 10 min preoperatively. In the control group (n = 20), the same volume of 0.9 % normal saline was administered in the same manner. The EC50 of propofol for successful i-gel insertion was determined using Dixon’s up-and-down method. The EC50 of propofol was calculated as the midpoint concentration after at least six crossover points had been obtained. For successful i-gel insertion, all of the following four factors were required—(1) no major movement of the body within 1 min of insertion, (2) no significant resistance to mouth opening, (3) cough ≤2, and (4) visible square wave capnogram without air leakage at a peak airway pressure of <10 cmH2O. Mean blood pressure (MBP) and heart rate (HR) were monitored during the peri-insertion period of i-gel.
Results
The EC50 of propofol for successful i-gel insertion was 3.18 μg/mL in the dexmedetomidine group and 6.75 μg/mL in the control group (p < 0.001). The incidence of hypotension (MBP <80 % of the baseline) during the peri-insertion period of i-gel was higher in the control group (p = 0.001), whereas the incidence of bradycardia (HR <80 % of the baseline) was higher in the dexmedetomidine group (p = 0.001).
Conclusions
Preoperative dexmedetomidine reduced the EC50 of propofol for successful i-gel insertion without muscle relaxants.