Nuñez S, Maisel A
Division of Cardiology, Veterans Affairs Medical Center and University of California, San Diego 92161, USA.
Am Heart J. 1998 Mar;135(3):383-8. doi: 10.1016/s0002-8703(98)70312-6.
Although thermodilution cardiac output (COtd) is the accepted method for monitoring patients with heart failure in the intensive care unit, it is particularly inaccurate in low-flow states and in the presence of tricuspid regurgitation; in addition, it does not adequately reflect the interaction between oxygen delivery and tissue oxygen extraction. We were concerned about the underuse of mixed venous oxygen saturation (SvO2) in this setting and hypothesized that it might be a more useful parameter than COtd for evaluating hemodynamic status and monitoring therapy in patients with severe congestive heart failure.
We determined the correlation coefficients between increasing dose of inotrope and each of the parameters COtd and SvO2 in 18 patients with congestive heart failure who received a 3-day trial of either milrinone or dobutamine during admission to the Veterans Affairs Medical Center in San Diego. In addition, we analyzed reproducibility of repeated COtd and SvO2 measurements taken at a single dose of inotrope.
In patients receiving milrinone the increase in dose correlated much better with SvO2 (average correlation coefficient 0.79) than with COtd; this stronger correlation with SvO2 was seen in 82% of the trials reviewed (p < 0.05). In addition, we found that repeated SvO2 measurements taken at a single dose of milrinone were more reproducible than COtd as indicated by smaller relative 95% confidence intervals. In patients receiving dobutamine no significant trend in correlation coefficients or reproducibility was observed.
The knowledge that there is a significant relation between SvO2 and increasing dose of milrinone therapy in patients with severe heart failure and tricuspid regurgitation has practical value for physicians monitoring these patients in the intensive care unit. We believe this study demonstrates the worth of SvO2 in detecting hemodynamic change during trials of milrinone therapy and that this parameter may in fact be more reproducible than traditional thermodilution methods.
虽然热稀释法心输出量（COtd）是重症监护病房中监测心力衰竭患者的公认方法，但在低流量状态和存在三尖瓣反流时其准确性特别差；此外，它不能充分反映氧输送与组织氧摄取之间的相互作用。我们担心在这种情况下混合静脉血氧饱和度（SvO2）未得到充分利用，并假设在评估重度充血性心力衰竭患者的血流动力学状态和监测治疗方面，它可能是比COtd更有用的参数。
我们确定了18例充血性心力衰竭患者在圣地亚哥退伍军人事务医疗中心住院期间接受米力农或多巴酚丁胺3天试验时，血管活性药物剂量增加与COtd和SvO2各参数之间的相关系数。此外，我们分析了在单一剂量血管活性药物下重复测量COtd和SvO2的可重复性。
在接受米力农治疗的患者中，剂量增加与SvO2的相关性（平均相关系数0.79）远优于与COtd的相关性；在82%的审查试验中观察到与SvO2的这种更强相关性（p<0.05）。此外，我们发现，如相对较小的95%置信区间所示，在单一剂量米力农下重复测量SvO2比COtd更具可重复性。在接受多巴酚丁胺治疗的患者中，未观察到相关系数或可重复性的显著趋势。
了解到重度心力衰竭和三尖瓣反流患者中SvO2与米力农治疗剂量增加之间存在显著关系，对于重症监护病房中监测这些患者的医生具有实际价值。我们认为这项研究证明了SvO2在米力农治疗试验期间检测血流动力学变化方面的价值，并且该参数实际上可能比传统热稀释法更具可重复性。
