每搏输出量变异度和胸腔内血容量指数对失血性休克犬容量状态的评价

目的探讨每搏输出量变异度（SVV）和胸腔内血容量指数（ITBI）在失血性休克犬容量状态评价中的意义。方法以改良Wiggers’法复制失血性休克犬模型,Swan-Ganz导管和PiCCO仪监测血流动力学,重复行容量负荷试验,根据每搏输出量的变化（△SV）是否大于5％分为反应组和无反应组。结果14只犬共行容量负荷试验134次,反应组94次,无反应组40次。容量负荷试验后反应组心率（HR）、平均动脉压（MAP）、SVV和ITBI的变化明显大于无反应组。反应组中心静脉压（CVP）和肺动脉楔压（PAWP）的变化明显小于无反应组。ITBI、SVV与ASV显著相关,HR、MAP、CVP、PAWP与ASV无明显相关。容量负荷试验后△CVP、△PAWP、△ITBI、△SVV与△SV显著相关,而△HR、△MAP与△SV无明显相关。受试犬操作特征（ROC）曲线：SVV的曲线下面积（AUC）为0．872,ITBI的AUC为0．689,明显高于HR、MAP、CVP和PAWP（0．294～0．593）。SVV大于9．5％对容量负荷试验有反应的敏感性为92．6％,特异性为82．5％。结论SVV和ITBI对容量状态的评价明显优于CVP和PAWP。SVV持续监测有助于容量状态评价和液体管理。

Assessment of stroke volume variation and intrathoracic blood volume index on the responsiveness to volume loading in mechanically ventilated canine with hemorrhagic shock

OBJECTIVE: To assess the significance of stroke volume variation (SVV) and intrathoracic blood volume index (ITBI) on the responsiveness to volume loading in mechanically ventilated canine with hemorrhagic shock. METHODS: Hemorrhagic shock canine model was established with the modified Wiggers' method. The heart rate (HR), mean artery pressure (MAP), central venous pressure (CVP), pulmonary artery wedge pressure (PAWP), intrathoracic blood volume index (ITBI) and stroke volume variation (SVV) were investigated by Swan-Ganz catheter or PiCCO monitor. Graded volume loading (VL) was performed. Successive responsive VLs were performed (increase in SV > 5% after VL) until continuous change in SV < 5% (unresponsive) was reached. RESULTS: Fourteen canines were studied and a total of 134 VLs were performed. In 94 VLs, an increase in SV of more than 5% was reached. In the other 40 VLs, increase in SV was less than 5%. The change of HR, MAP, ITBI, SVV in responsive were more than those of unresponsive after VL. The change of CVP, PAWP in responsive were less than those of unresponsive. Significant correlation was found between DeltaSV after VL and the baseline values of ITBI, SVV. No correlation was found between DeltaSV and HR, MAP, CVP, PAWP. Significant correlations were also found between DeltaSV and DeltaCVP, DeltaPAWP, DeltaITBI, DeltaSVV after fluid loading. No correlation was found between DeltaSV and DeltaHR, DeltaMAP. By using receiver operating characteristic analysis, the area under the curve were 0.872 for SVV and 0.689 for ITBI, more than those of HR, MAP, CVP, PAWP statistically. As SVV value of 9.5% or more will predict an increase in the SV of at least 5% in response to a VL with a sensitivity of 92.6% and a specificity of 82.5%. CONCLUSIONS: SVV and ITBI were more useful indicators than CVP and PAWP on the assessment of responsiveness to volume loading. SVV as a functional preload parameter and for on-line monitoring may help to improve the hemodynamic management.