Intravenous dexmedetomidine pre-medication reduces the required minimum alveolar concentration of sevoflurane for smooth tracheal extubation in anesthetized children: a randomized clinical trial

BACKGROUND: It has been known that Dexmedetomidine pre-medication enhances the effects of volatile anesthetics, reduces the need of sevoflurane, and facilitates smooth extubation in anesthetized children. This present study was designed to determine the effects of different doses of intravenous dexmedetomidine pre-medication on minimum alveolar concentration of sevoflurane for smooth tracheal extubation (MAC(EX)) in anesthetized children. METHODS: A total of seventy-five pediatric patients, aged 3–7 years, ASA physical status I and II, and undergoing tonsillectomy were randomized to receive intravenous saline (Group D(0)), dexmedetomidine 1 μg∙kg(−1) (Group D(1)), or dexmedetomidine 2 μg∙kg(−1) (Group D(2)) approximately 10 min before anesthesia start. Sevoflurane was used for anesthesia induction and anesthesia maintenance. At the end of surgery, the initial concentration of sevoflurane for smooth tracheal extubation was determined according to the modified Dixon’s “up-and-down” method. The starting sevoflurane for the first patient was 1.5% in Group D(0), 1.0% in Group D(1), and 0.8% in Group D(2), with subsequent 0.1% up or down in next patient based on whether smooth extubation had been achieved or not in current patient. The endotreacheal tube was removed after the predetermined concentration had been maintained constant for ten minutes. All responses (“smooth” or “not smooth”) to tracheal extubation and respiratory complications were assessed. RESULTS: MAC(EX) values of sevoflurane in Group D(2) (0.51 ± 0.13%) was significantly lower than in Group D(1) (0.83 ± 0.10%; P < 0.001), the latter being significantly lower than in Group D(0) (1.40 ± 0.12%; P < 0.001). EC(95) values of sevoflurane were 0.83%, 1.07%, and 1.73% in Group D(2), Group D(1), and Group D(0), respectively. No patient in the current study had laryngospasm. CONCLUSION: Dexmedetomidine decreased the required MAC(EX) values of sevoflurane to achieve smooth extubation in a dose-dependent manner. Intravenous dexmedetomidine 1 μg∙kg(−1) and 2 μg∙kg(−1) pre-medication decreased MAC(EX) by 41% and 64%, respectively. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR): ChiCTR-IOD-17011601, date of registration: 09 Jun 2017, retrospectively registered.