Administration Of Dexmedetomidine In Patients Undergoing Awake Craniotomy With Intra-operative Magnetic Resonance Imaging

Objectives:Patients with brain tumor, especially near eloquent cortex, may benefit from awake craniotomy or/and intra-operative magnetic resonance imaging (iMRI),which allows maximal tumor resection with minimal risks of functional damage.The intra-operative MRI prolongs the duration of the surgery and anesthesia.It is necessary for anesthesiologists to make individual anesthesia protocols to maintain the patients’airway,arouse them smoothly and improve their comfort during prolonged awake craniotomies. Recently target control infusion of propofol and remifentanil is widely used in awake craniotomy. Dexmedetomidine, a highly selective alpha-2 adrenoreceptor agonist,has benefits of dose-dependent sedative, analgesic and anti-anxiety.lt almostly has no respiratory suppression. However, few datas was found on evaluating the effects of dexmedetomidine as an anesthetic adjuvant in awake craniotomy. In the current study,we would evaluate the efficacy of dexmedetomidine as an anesthetic adjuvant in patients undergoing awake craniotomy with intra-operative magnetic resonance imaging.Methods:Forty patients with gliomas in or adjacent to eloquent areas were included in this study, and randomized into 2 groups.Patients in P group(n=20) received propofol and remifentanil perioperatively. Patients in group D (n=20) received the combination of dexmedetomidine,propofol and remifentanil.All, patients were given scalp block before induction, Monitered Anesthesia Care(MAC) and magnetic resonance imaging intra-operatively.lnvasive systolic blood pressure (SBP) and heart rate(HR) were recorded at the following time points, including before anesthesia(TO),after induction(OAA/S score =1,T1),skin incision(T2),brain mapping(T3),and closure of dura (T4).The effect-site concentration of propofol and infusion rate of remifentanil were recorded at T1 and T2.Anethestic consumption,PaCO2 before and after induction,arousal time and perioperative complications were also recorded.Intraoperative brain relaxation were evaluated by the same surgeon after dura was open.Results:Effect-site concentration of propofol in group D at T1 and T2 was significantly lower than that in group P(P<0.05).Propofol comsumption in group D was significantly less than that in group P(P<0.05).Compared with group P,SBP in group D was significantly lower at T3(P<0.05),and HR in group D was significantly slower at T1,T2 and T3(P<0.05).PaCO2 after induction was significantly higher than that before induction in both groups(P<0.01).PaCO2 after induction in group D was significantly higher than that in group P(P<0.01).Patients in both groups were awakened smoothly and brain mapping were performed successfully.There was no significantly difference in the arousal time between the two groups.The incidence of high blood pressure and tachycardia in group D was significantly lower than that in group P.There was no difference between the 2 groups in the incidence of other adverse events (P>0.05)Conclusions:As an anesthetic adjuvant,dexmedetomidine allows the patients comfortably and smoothly undergoing the awake craniotomy in intra-operative magnetic resonance imaging environment. Dexmedetomidine significantly reduced the effect-site concentrations and comsumption of propofol,decreased the incidence of HBP and tachycardia. Administration of dexmedetomidine might increase the incidence of hypercarbia for patients with spontaneous respiration in awake craniotomy.