右美托咪定辅助全麻下每搏量变异度监测机体容量状况的准确性研究

Accuracy of stroke volume variation in monitoring blood volume in patients under general anesthesia with dexmedetomidine

目的 评价每搏量变异度（SVV）监测右美托咪定辅助全麻下患者全身血容量变化的准确性及持续输注右美托咪定是否会影响SVV。方法 择期平卧位行开腹胃肠手术患者60例,年龄37～65岁,ASAⅠ～Ⅲ级,随机分为右美托咪定组（n=30）和对照组（n=30）。对照组采用常规诱导及术中麻醉维持;右美托咪定组在对照组的麻醉方案基础上加用右美托咪定负荷量0.5μg/kg,并以0.5μg/（kg·h）的速率持续输注维持麻醉。待气管插管5 min后、手术开始前以0.3 ml/（kg·min）的速率输注6%羟乙基淀粉130/0.4氯化钠注射液,输注量7 ml/kg。记录输注羟乙基淀粉氯化液前即刻（T1）和输注完毕后3 min（T2）的平均动脉压（MAP）、心率（HR）、SVV、心指数（CI）、每搏量指数（SVI）,并计算SVV与SVI的变化率（ΔSVV、ΔSVI）。以ΔSVI≥10%为监测血容量变化的标准时,绘制SVV监测血容量变化的受试者工作特征（ROC）曲线。结果 ROC曲线结果分析显示,右美托咪定组SVV的诊断阈值为10.5%,判断扩容有效的灵敏度为90%,特异度为86.7%,曲线下面积为0.932;对照组的诊断阈值为11.5%,判断扩容有效的灵敏度为86.7%,特异度为83.3%,曲线下面积为0.941。对照组与右美托咪定组在TI与T2的SVV差值（ΔSVV）的差异无统计学意义。结论 在右美托咪定0.5μg/kg负荷量、0.5μg/（kg·h）维持量的条件下,SVV判断患者液体治疗的扩容有效阈值为10.5%。该剂量的右美托咪定不会影响SVV对全身血容量的监测。

Objective To evaluate the accuracy of stroke volume variation（SVV） in monitoring the blood volume in patients under general anesthesia with dexmedetomidine and explore the influence of SVV under continuous infusion of dexmedetomidine.Methods Sixty ASA Ⅰ～Ⅲ patients of both genders aged 37～65 years old undergoing elective gastrointestinal surgery in the supine position were randomly divided into 2 groups：dexmedetomidine group（group Y,n=30） and the control group（group C,n=30）.Conventional anesthesia was used in Group C.Beyond the conventional anesthesia,0.5μg/kg loading-dose and 0.5 μg/（kg· h） maintaining-dose of dexmedetomidine were used in group Y.6% hydroxyethyl starch 130/0.4 sodium chloride solution 7 ml/kg was infused intravenously 5 min after endotracheal intubation and before the surgery at a rate of 0.3 ml/（kg· min） in both groups.MAP,HR,SVV,CI and SVI were recorded before（T1） and at 3min after the infusion of hydroxyethyl starch（T2）,and the change rate of SVV and SVI（ΔSVV,ΔSVI） were calculated.The criterion for effective volume expansion was △SVI≥10%.The ROC curve for SVV in determining the volume expansion responsiveness was plotted and the diagnostic threshold was determined.Results ROC curve showed that the diagnostic threshold of SVV was 10.5% in group Y,and 11.5% in group C.The sensitivity and specificity in determining effective volume expansion were 90% and 86.7% in group Y and 86.7% and 83.3% in group C respectively.The difference of ΔSVV in both groups was not statistically significant.Conclusion The threshold of SVV in determining the volume expansion responsiveness with 0.5 μg/kg loading- dose and 0.5 μg/（kg · h） maintaining- dose of dexmedetomidine during fluid thempy is 10.5%.The SVV in monitoring the blood volume can not be influenced by infusing dexmedetomidine at this dose.