Abstract:

BACKGROUND: The inhalational anesthetic sevoflurane is often used in craniocerebral surgery for its advantages of quick onset, stable circulation, high safety, and few adverse reactions. However, it can also lead to abnormal blood pressure and heart rate, as well as restlessness and pain. Therefore, an auxiliary anesthetic is needed to help reduce adverse reactions. Dexmedetomidine is a potent and highly selective α2 adrenergic receptor agonist that has anti-anxiety, hypnotic, analgesic, sedative, and sympatholytic properties. Dexmedetomidine has been shown to reduce restlessness after sevoflurane inhalation anesthesia and minimize perioperative hemodynamic fluctuation. However, its application in craniocerebral surgery should be validated.

OBJECTIVE: To investigate the efficacy of dexmedetomidine in craniocerebral surgery under sevoflurane inhalation anesthesia.

METHODS: The prospective, single-center, randomized, controlled study will be performed in Taihe Hospital (Shiyan, China). The 1308 patients to be included in this study will be randomly divided into a trial group and control group (n=654 patients per group) based on a table of random permutations. In both groups, sevoflurane will be used for induction of anesthesia for craniocerebral surgery. In the trial group, 1 μg/kg dexmedetomidine will be injected intravenously for 10 minutes commencing 15 minutes before anesthesia induction, and then continuously pumped at 0.3 μg/kg per hour until 30 minutes before surgery. In the control group, 0.9% sodium chloride injection will be administered in the same way and at the same injection rate. This trial was approved by the Ethics Review Committee of Taihe Hospital on December 8, 2015 (Approval No. 2015GJJ-087). Participants will not be blind to the study protocol or procedure, and will provide signed informed consent. This study was registered with Chinese Clinical Trial Registry on March 2, 2020 (registration No. ChiCTR2000030459). Protocol version: 1.0.

RESULTS AND CONCLUSION: The primary outcome of this study is recovery time. Secondary outcomes of this study include anesthesia, recovery, and adverse events, as well as vital signs, stress index, and cerebral metabolic rate of oxygen consumption at different time points (before and after administration of the loading dose of dexmedetomidine, during anesthesia induction, at the beginning of craniocerebral surgery, during craniocerebral surgery, at the end of craniocerebral surgery, and at the time of recovery). A pilot study involving 190 patients who underwent craniocerebral surgery was performed between March 2016 and February 2017. These 190 patients randomly received either sevoflurane anesthesia (n=95, control group) or dexmedetomidine and sevoflurane anesthesia (n=95, trial group). Results of the pilot group showed that anesthesia time, intraoperative bleeding volume, intraoperative infusion volume, recovery time, and extubation time were similar between trial and control groups (P > 0.05). However, compared with the control group, the administered dosages of vasoactive drugs ephedrine and esmolol were significantly lower (P < 0.05) in the trial group. Heart rate and electroencephalography bispectral index after administration of the loading dose of dexmedetomidine, during anesthesia induction, at the beginning of craniocerebral surgery, during craniocerebral surgery, at the end of craniocerebral surgery, and at the time of recovery were significantly higher in the trial group compared with the control group (P < 0.05). At the beginning of craniocerebral surgery, during craniocerebral surgery, at the end of craniocerebral surgery, and at the time of recovery, mean arterial pressure in the trial group was significantly higher compared with the control group (P < 0.05). After administration of the loading dose of dexmedetomidine, during anesthesia induction, at the beginning of craniocerebral surgery, during craniocerebral surgery, at the end of craniocerebral surgery, and at the time of recovery, blood glucose level in the trial group was significantly higher compared with the control group (P < 0.05). After administration of the loading dose of dexmedetomidine, during anesthesia induction, and at the beginning of craniocerebral surgery, cortisol concentrations in the trial group were significantly lower compared with the control group (P < 0.05). During craniocerebral surgery, at the end of craniocerebral surgery, and at the time of recovery, jugular bulb venous blood oxygen saturation, difference in oxygen content between arterial and jugular venous blood, and cerebral metabolic rate of oxygen consumption in the trial group were significantly higher compared with the control group (P < 0.05). Findings from this study will help determine whether dexmedetomidine can reduce hemodynamic fluctuation, lower stress index, and protect the brain in patients who undergo craniocerebral surgery under inhalation anesthesia with sevoflurane. The results can provide evidence to support clinical application of dexmedetomidine combined with sevoflurane for craniocerebral surgery. 

Key words: dexmedetomidine, α2-adrenoceptor agonist, sevoflurane, craniocerebral surgery, inhalation anesthesia, blood glucose, cortisol, cerebral oxygen metabolism, randomized controlled trial