Effects Of Low-dose Dexmedetomidine On Autonomic Nerves And Hemodynamics In Patients Undergoing Endoscopic Sinus Surgery

Objective:To observe the effects of intravenous infusion of dexmedetomidine hydrochloride on sympathetic,parasympathetic parameters and its balance by using a heart rate variability analyzer in general anesthesia endoscopic sinus surgery,and combined with the intraoperative hemodynamics.Explore the clnical significance and meanwhile provide a theoretical basis for clinical anesthesia.Methods:In this study,40 patients whose sympathetic parameter higher than 65 were included after entering the operating room.ASA grade Ⅰ-Ⅱ,aged 18-65 years.The patients were randomly divided into two groups:control group(group C)and experimental group(group E).Group E was injected with dexmedetomidine 0.2μg/kg within 10 minutes before anesthesia induction.The maintenance rate was 0.2μg/(kg ·h).Group C was given 0.9%sodium chloride injection.Anesthesia induction:Followed by intravenous injection of sufentanil(0.4 μg/kg),etomidate(0.2 mg/kg),cisatracurium(0.2 mg/kg)and target-controlled infusion of propofol(plasma target concentration 1.5μg/ml,preload time is 6 minutes).When the propofol reach the plasma target concentration,performed the oral tracheal intubation and mechanical control ventilation.Target-controlled infusion of remifentanil 1 minute before the operation(remifentanil effect-concentration 1.5ng/ml).Anesthesia maintenance:Target-controlled infusion of propofol and remifentanil throughout the operation.Adjusted the target concentrations of propofol and remifentanil according to the depth of anesthesia(BIS values fluctuate between 40-60)and the hemodynamics conditions.(propofol plasma concentration range 2-2.5μg/ml,remifentanil effect concentration 1.5ng/ml).Intraoperative fluid speed maintain at 6-8ml/(kg · h).Monitoring indexs:(1)Autonomic nerves indexs:sympathetic nerve indexs,parasympathetic nerve indexs.(2)Hemodynamic indexs:systolic blood pressure(SBP),diastolic blood pressure(DBP),mean arterial pressure(MAP),heart rate(HR).(3)Other indexs:bispectral index(BIS),end-tidal carbon dioxide partial pressure(PetCO2),vasoactive drug dose and extubation propofol plasma concentration Monitoring points:baseline(T0),infusion of dexmedetomidine or 0.9%sodium chloride injection after 10 minutes(T1),anesthesia induction(T2),intubation(T3),at the beginning of surgery(T4),the highest systolic blood pressure during the surgery(T5),the lowest systolic blood pressure during the surgery(T6),at the end of surgery(T7),extubation(T8).Result:(1)General situations:gender,age,height,weight and BMI have no statistical significance(P>0.05).(2)Autonomic nerves indexs:sympathetic(parasympathetic)indexs at T1,T2,T3,T4,T5,T6,T7,T8,the experimental group are lower(higher)than the control group.The differences have the statistical significance(P<0.05).(3)Hemodynamic indexs:systolic blood pressure(SBP).diastolic blood pressure(DBP),mean arterial pressure(MAP)and heart rate(HR)at T1,T2,T3,T4,T5,T7,T8,the experimental group are lower than the control group.The differences have the statistical significance(P<0.05).(4)There is no statistical significance between the two groups in the bispectral index(BIS),end-tidal carbon dioxide partial pressure(PetCO2),vasoactive drug dose and extubation propofol plasma concentration(P>0.05).Conclusion:During the general anesthesia undergoing endoscopic surgery,preconditioning and intraoperative continuous intravenous injection of low-dose dexmedetomidine,can effectively inhibit the sympathetic nerve excitement,improve the sympathetic and parasympathetic nerve balance,reduce the stress response at the intubation and extubation,thereby enhancing the perioperative hemodynamic stability,improving the quality of anesthesia.