Young-Eun Jang1, Yong-Chul Kim1, Hyun-Kyu Yoon1, Young-Tae Jeon2, Jung-Won Hwang2, Eugene Kim1, Hee-Pyoung Park3. 1. Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, South Korea. 2. Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea. 3. Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, South Korea. hppark@snu.ac.kr.
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.
RCT Entities:
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.
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