Lichtwarck-Aschoff M, Beale R, Pfeiffer U J
Department of Anaesthesiology and Surgical Intensive Care Medicine, Zentralklinikum Augsburg, Germany.
J Crit Care. 1996 Dec;11(4):180-8. doi: 10.1016/s0883-9441(96)90029-5.
Central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP) and right ventricular end-diastolic volume (RVEDV) are often regarded as indicators of both circulating blood volume and cardiac preload. to evaluate these relationships, the response of each variable to induced volume shifts was tested. The relationships between these variables and cardiac index (CI) and stroke volume index (SVI) was also recorded to assess the utility of each variable as an indicator of cardiac preload. The responses of the new variable intrathoracic blood volume (ITBV) to the same maneuvers was also tested. To examine the effects of changes in cardiac output alone on ITBV, the effects of infusing dobutamine were studied.
Ten anesthetized piglets were studied during conditions of normovolemia, hypovolemia, and hypervolemia. The effects of an infusion of dobutamine were examined under normovolemia and hypovolemia. Cardiac output was measured by thermo-dilution, and ITBV was measured by double-indicator dilution.
CI was correlated to CVP with r2 = .42 (P < or = .01), to PAOP with r2 = .43 (P < or = .01), to RVEDV index with r2 = .21 (P < or = .01), and to ITBV with r2 = .78 (P < or = .01) (pooled absolute values). Bias (mean difference of the percent changes with normovolemia = 100%) +/- 1 SD; for SVI - ITBV index was 1 +/- 22%, for SVI - CVP it was -128 +/- 214%; for SVI - PAOP it was -36 +/- 46%; and for SVI - RVEDV index it was 1 +/- 29%. Dobutamine infusion increased heart rate (to about 190 x min-1 and CI by 30% in normovolemia and hypovolemia, while ITBV remained basically unchanged.
Under the experimental conditions chosen neither CVP, PAOP, nor RVEDV reliably indicated changes in circulating blood volume, nor were they linearly and tightly correlated to the resulting changes in SVI. ITBV reflected both changes in volume status and the resulting alteration in cardiac output. The possibility that ITBV might be cardiac output-dependent was not supported. ITBV, therefore, shows potential as a clinically useful indicator of overall cardiac preload.
中心静脉压（CVP）、肺动脉闭塞压（PAOP）和右心室舒张末期容积（RVEDV）常被视为循环血容量和心脏前负荷的指标。为评估这些关系，测试了每个变量对诱导性容量变化的反应。还记录了这些变量与心脏指数（CI）和每搏量指数（SVI）之间的关系，以评估每个变量作为心脏前负荷指标的效用。还测试了新变量胸腔内血容量（ITBV）对相同操作的反应。为研究仅心输出量变化对ITBV的影响，研究了输注多巴酚丁胺的效果。
对10只麻醉仔猪在正常血容量、低血容量和高血容量状态下进行研究。在正常血容量和低血容量状态下检查输注多巴酚丁胺的效果。通过热稀释法测量心输出量，通过双指示剂稀释法测量ITBV。
CI与CVP的r2 = 0.42（P≤0.01），与PAOP的r2 = 0.43（P≤0.01），与RVEDV指数的r2 = 0.21（P≤0.01），与ITBV的r2 = 0.78（P≤0.01）（合并绝对值）。偏差（正常血容量时百分比变化的平均差异 = 100%）±1标准差；SVI - ITBV指数为1±22%，SVI - CVP为 - 128±214%；SVI - PAOP为 - 36±46%；SVI - RVEDV指数为1±29%。在正常血容量和低血容量状态下，输注多巴酚丁胺使心率增加（至约190次/分钟），CI增加30%，而ITBV基本保持不变。
在所选择的实验条件下，CVP、PAOP和RVEDV均不能可靠地指示循环血容量的变化，它们与SVI的相应变化也不存在线性紧密相关性。ITBV既反映了容量状态的变化，也反映了心输出量的相应改变。未证实ITBV可能依赖于心输出量。因此，ITBV显示出作为临床上有用的整体心脏前负荷指标的潜力。
