Clinical Study Of Dexmedetomidine Used In Neurophysiological Monitoring In Neurosurgery

Objective:To investigate the effect of dexmedetomidine(DEX) used in neurophysiological monitoring in neurosurgery. Methods:Sixty ASA ⅠorⅡ patients aged 18-55 yr with a body mass index of 18-24kg/m2 undergoing neurosurgery receiving neurophysiological monitoring were randomly divided into 3 groups(n=20 each): control group(group C), dexmedetomidine 0.5μg/kg group(group DL) and dexmedetomidine 1.0μg/kg group(group DH). In group DL and DH, dexmedetomidine 0.5μg/kg and 1.0μg/kg were infused over 10 min respectively before anesthesia induction, and then were infused at a rate of 0.5μg·kg-1·h-1 toward the end of operation. Group C received the equal volume of normal saline. HR, MAP and BIS were recorded at admission to the operating room(T0), immediately after intubation(T1), when the muscle relaxants were stopped(T2) and at 30 minutes later(T3). Venous blood samples were also taken at the same time to measure the serum concentrations of norepinephrine and cortisol. The current intensity and the time when first CMAP was induced after muscle relaxant was stopped, the amplitudes and latencies of N20 and CMAP at 50 minutes after muscle relaxants stopped(T4), the total consumption of anesthetics, and development of adverse effects were also recorded. Results:1. Compared with group C, in group DL and DH HR at T1-T3, MAP at T2-T3 and the serum concentrations of norepinephrine and cortisol at T2-T3 were decreased, meanwhile in group DH MAP at T1 was increased. Compared with group DL, in group DH HR at T1-T2, MAP at T2-T3 and the serum concentrations of norepinephrine and cortisol at T2-T3 were decreased, meanwhile MAP at T1 was increased(P<0.05).2. The current intensities of inducing CMAP in group C, group DL and group DH were decreased one by one. The latency of N20 was shorter and the amplitudes of N20 and CMAP were higher at T4 in group DL and DH than in group C. The latency of N20 was shorter and amplitude higher in group DH than in group DL(P<0.05)。3. The amount of propofol consumed in group C, group D L and group DH were decreased in turn. The amount of remifentanil consumed is lower in group DH than in group C(P<0.05).4. There was one patient with epileptic seizures during electrical stimulation in group C. Compared with group C, the incidences of hypertension and tachycardia were decreased, and the incidence of bradycardia was increased in group DL and DH(P<0.05). Conclusion:In neurophysiological monitoring in neurosurgery, dexmedetomide 1.0μg/kg and 0.5μg/kg infused intravenously before anesthesia induction, and then are infused at a rate of 0.5μg·kg-1·h-1, could maintain hemodynamic stability, inhibit the stress reaction, decrease the effects of the anaesthetics in neurophysiological monitoring, and reduce the incidences of hypertension and tachycardia. In the aspects of inhibiting the stress reaction and decreasing the effects of the anaesthetics in neurophysiological monitoring, dexmedetomidine 1.0μg/kg group is better than dexmedetomidine 0.5μg/kg group.