不同潮气量通气患者液体治疗时每搏量变异度判断扩容效应的阈值

The threshold of stroke volume variation in deteriuining volume expansion responsiveness during fluid therapy in patients ventilated with different tidal volumes

目的确定不同潮气量通气患者液体治疗时每搏量变异度（SVV）判断扩容效应的阈值。方法拟在全麻下行胃肠手术的患者50例，ASA分级I或Ⅱ级，年龄20～75岁，随机分为2组（n=25）：潮气量8ml／kg组（v1组）和潮气量10ml／kg组（V2组）。麻醉诱导后以0．4m1．kg-1·min-1的速率静脉输注6％羟乙基淀粉130／0．4氯化钠注射液，输注量7ml／kg。于液体治疗前即刻（L）和液体治疗结束后3min（T2）时记录MAP、HR、CVP、CI、SVV、每搏指数（SVI）、体循环血管阻力指数（SVRI），计算SVV和CI的变化率（ASVV和△CI）。以△CI≥15％为扩容有效标准，绘制SVV判断扩容效应的ROC曲线，确定诊断阈值。结果ROC曲线分析结果：V1组SVV的诊断阈值为10．5％，判断扩容有效的灵敏度为93．3％，特异度为75．0％；V2组SVV的诊断阈值为13．5％，判断扩容有效的灵敏度为87．5％，特异度为85．7％；V1组SVV判断扩容有效的ROC曲线下面积及其95％可信区间为0．946（0．860～1．031），V2组为0．951（0．868～1．034）。V1组和V2组ASVV与△CI呈负性相关，相关系数分别为-0．553和-0．602（P〈0．01）。结论潮气量为8ml／kg和10ml／kg机械通气下，SVV判断患者液体治疗时扩容有效的阈值分别为10．5％和13．5％。

Objective To determine the threshold of stroke volume variation （SVV） in determining the volume expansion responsiveness during fluid therapy in patients ventilated with different tidal volumes. Methods Fifty ASA I or II patients aged 20-75 yr undergoing elective gastrointestinal surgery under general anesthesia were randomly divided into 2 tidal volume groups （ n = 25 each） ： group I VT 8 ml/kg （ group Vl ） and group II VT 10 ml/kg （group V2 ）. Radial artery was eannulated and connected to Vigelo monitor for continuous monitoring of cardiac index （CI）, stroke volume index （SVI）, systemic vascular resistance index （SVRI） and SVV. Internal jugular vein was cannulated for CVP monitoring. Anesthesia was induced with midazolam, propofol, fentanyl and rocuronium and maintained with intravenous propofol and remifentanil infusion. BIS was maintained at 40-50 during anesthesia. The patients were intubated and mechanically ventilated （VT 8/10 ml/kg, RR 8-12 bpm, oxygen flow 2 L/min）. 6% HES 130/0.4 7 ml/kg was infused iv at a rate of 0.4 ml·kg-1·min-1 after induction of anesthesia. MAP, HR, CVP, CI, SVV, SVI and SVRI were recorded before and at 3 min after fluid therapy. The changing rate of SVV （△SVV） and CI （△CI） were calculated. The criterion for effective volume expansion was ACI 15%. The ROC curve for SVV in determring 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 V1 and 13.5 % in group V2 . The sensitivity and specificity in determining effective volume expansion were 93.3 % and 75.0 % in group V1 and 87.5 % and 85.7 % in group V2 respectively. The area under the curve for SVV and 95% confidence interval （CI） were 0.946 （0.860-1.031） in group V1 and 0.951 （0.868-1.034） in group V2 . △SVV was negatively correlated with △CI in group V1 （ = 0. 553） and V2 （ = 0. 602）. Conclusion The threshold of SVV in determining the volume expansion responsiveness during fluid therapy is 10.5 % and 13.5 % in mechanically ventilated patients with tidal volmne of 8 and 10 ml/kg respectively.