BACKGROUND: 

Cardiac output is an important hemodynamic variable and determines oxygen delivery. In contrast to blood pressure, cardiac output is rarely measured even in high-risk surgical patients, suggesting that clinicians consider blood pressure to be a reasonable indicator of systemic blood flow. However, the relationship depends on constant vascular tone and volume, both of which routinely vary during anesthesia and surgery. We therefore tested the hypothesis that there is no clinically meaningful correlation between mean arterial pressure and cardiac index in major abdominal surgery patients.

METHODS: 

In this prospective observational study, we assessed the relationship between mean arterial pressure and cardiac index in 100 patients having major abdominal surgery under general anesthesia.

RESULTS: 

The pooled within-patient correlation coefficient calculated using meta-analysis methods was r = 0.34 (95% confidence interval, 0.28–0.40). Linear regression using a linear mixed effects model of cardiac index on mean arterial pressure revealed that cardiac index increases by 0.014 L·min⁻¹·m⁻² for each 1 mm Hg increase in mean arterial pressure. The 95% Wald confidence interval of this slope was 0.011 to 0.018 L·min⁻¹·m⁻²·mm Hg⁻¹ and thus within predefined equivalence margins of −0.03 and 0.03 L·min⁻¹·m⁻²·mm Hg⁻¹, thereby demonstrating lack of clinically meaningful association between mean arterial pressure and cardiac index.

CONCLUSIONS: 

There is no clinically meaningful correlation between mean arterial pressure and cardiac index in patients having major abdominal surgery. Intraoperative blood pressure is thus a poor surrogate for cardiac index.

中文翻译：

---

腹部大手术患者平均动脉压与心脏指数之间的关系：一项前瞻性观察队列研究

背景： 

心输出量是一个重要的血流动力学变量并决定氧气输送。与血压相比，即使在高危手术患者中也很少测量心输出量，这表明临床医生认为血压是全身血流的合理指标。然而，这种关系取决于恒定的血管张力和容量，这两者在麻醉和手术期间通常会发生变化。因此，我们检验了腹部大手术患者的平均动脉压和心脏指数之间没有临床意义相关性的假设。

方法： 

在这项前瞻性观察研究中，我们评估了 100 名在全身麻醉下进行腹部大手术的患者的平均动脉压和心脏指数之间的关系。

结果： 

使用荟萃分析方法计算的合并患者内相关系数为r = 0.34（95% 置信区间，0.28-0.40）。使用心脏指数对平均动脉压的线性混合效应模型的线性回归显示，平均动脉压每增加 1 mm Hg，心脏指数就会增加 0.014 L·min ^-1 ·m ^-2。该斜率的 95% Wald 置信区间为 0.011 至 0.018 L·min ^-1 ·m ^-2 ·mm Hg ^-1，因此在 -0.03 和 0.03 L·min ^-1 ·m ^-2 ·mm Hg的预定义等价范围内^-1，从而证明平均动脉压和心脏指数之间缺乏临床上有意义的关联。

结论： 

腹部大手术患者的平均动脉压和心脏指数之间没有临床意义的相关性。因此，术中血压不能很好地替代心脏指数。