胸内血容量指数和中心静脉压反映容量状态的评价

Evaluation of reflection of fluid volume state such as intrathoracic blood volume index and central venous pressure

目的:比较在机械通气时,随潮气量(Vt)的变化,中心静脉压(CVP)和胸腔内血容量指数(ITBVI)的变化趋势以及两者与心脏指数(CI)的相关性。方法:选取24例行有创机械通气和脉搏轮廓动脉压波形分析法(PiCCO)监测的患者,根据CI分为心功能正常组[CI≥2.2L/(min·m2)]和心功能低下组[CI<2.2L/(min·m2)]。在同步间歇指令通气(SIMV)模式下,调整Vt分别维持于6、10、15mL/kg体重水平,以上各种条件维持20min后测量呼吸力学及血流动力学指标.实验过程中以上支持条件随机选择进行。结果:(1)在所有患者,CI,ITBVI随潮气量升高而下降,平均气道压(Pmeans)随潮气量升高而升高,CVP在各组间无明显变化。(2)CVP在各实验组与CI均无相关性;在心功能低下组,ITBVI与CI有相关性(R为0.679,P<0.05)。结论:胸腔内血容量指数能更准确地反映机体容量状态和心脏前负荷,与心脏指数有较好的相关性。

Objectives To compare the changing trends [ GS W1 ] of intrathoracic blood volume index （ITBVI） and central venous pressure （CVP） and their correlations with cardiac index（CI） according to changes of tidal volume （VT） during mechanical ventilation. Methods 24 patients who performed invasive mechanical ventilation and pulse index continuous cardiac output （PiCCO）monitoring were divided into normal cardiac function group [CI t〉 2.2 L/（min·m）] and heart failure group [CI 〈 2.2 L/（min·m）] according to CI.Under the synchronized intermittent mandatory ventilation （SIMV） mode,the VT was adjusted at 6, 10,15 mL/kg levels. Respiratory parameters and hemodynamic data were collected 20 minutes after all above conditions. All the ventilation conditions were continued randomly. Results （1）In all the patients, CI and ITBVI decreased as VT increased, the mean airway pressure （Pmean） increased as VT increased ; CVP had no significant changes during the three groups. （2）CVP had no correlations with Ct during all the groups.ITBVI had correlations with CI in the heart failure group （R = 0.679, P 〈 0.05）. Conclusions ITBVI can reflect preload of the heart more accurately,it had better correlations with CI.