Influence of continuous renal replacement therapy on cardiac output measurement using thermodilution techniques.
Influence of continuous renal replacement therapy on cardiac output measurement using thermodilution techniques.
复制标题
连续肾脏替代疗法对使用热稀释技术测量心输出量的影响。
作者：
D. Heise;M. Faulstich;O. Mörer;A. Bräuer;M. Quintel
背景
急性肾衰竭（ARF）是危重患者最常见的并发症之一，连续性肾脏替代治疗（CRRT）是重症监护患者的典型治疗方案。ARF的促成因素，如感染性休克和血流动力学不稳定，需要延长血流动力学监测，同时使用CRRT和心输出量测量是常见的。有鉴于此，需要对CRRT与通过热稀释法测量的心输出量之间的相互作用进行系统分析。心输出量（CO）通常采用基于热稀释法的方法测量危重患者。该方法是准确的，但测量受不恒定的指示剂体积或血液温度变化的影响。由于连续性肾脏替代治疗（CRRT）可能会改变血容量和温度，因此我们研究了其对基于热稀释法的CO测量的影响。
方法
研究了32例同时接受CRRT和CO监测的重症监护患者。血液动力学参数首先在CRRT期间通过冷盐水推注进行五次测量。在CRRT关闭后进行了另外5次测量，在CRRT重新启动后进行了最后5次测量。在使用肺动脉导管的患者中进行了50个测量系列，在使用经皮热稀释法（PiCCO®）的患者中进行了25个测量系列。
结果
在关闭或打开CRRT后，每个系列中的首次测量值与平均值的偏差最明显。当排除这些测量值时，有和无CRRT的平均CO值差异显著，但<7%（P<0.05）。
结论
仅在CRRT关闭或打开后立即观察到实质性测量误差。后续CO测量不取决于CRRT状态。通常不建议在测量CO之前中断CRRT，但是，如果中断，在开始首次测量之前等待血液温度达到稳定状态至关重要。
BACKGROUND
Acute renal failure (ARF) ranks among the most frequent complications in critically ill patients and continuous renal replacement therapy (CRRT) is a typical treatment regimen in intensive care patients. Contributing factors to ARF, such as septic shock and hemodynamic instability require extended hemodynamic monitoring, and the simultaneous use of CRRT and cardiac output measurement is common. In view of this, a systematic analysis of the interaction between CRRT and cardiac output measurements by thermodilution is warranted. Cardiac output (CO) is commonly measured with thermodilution-based methods in critically ill patients. The methods are accurate but the measurements are affected by inconstant indicator volumes or changes in blood temperature. Because continuous renal replacement therapy (CRRT) may alter blood volume and temperature, we investigated its effect on thermodilution-based CO measurement.
METHODS
Thirty-two intensive care patients with both CRRT and CO monitoring were studied. Hemodynamic parameters were first measured in quintuple with bolus injections of cold saline during CRRT. Further five measurements were performed after CRRT had been shut off, and a final five measurements were performed after it had been restarted. Fifty measurement series were performed in patients with a pulmonary artery catheter and 25 in patients using a transpulmonary thermodilution method (PiCCO®).
RESULTS
The first measurements in each series after switching CRRT off or on deviated most markedly from the average. When these measurements were excluded, the averaged CO values with and without CRRT differed significantly but by <7% (P<0.05).
CONCLUSION
Substantial measurement error was only observed immediately after CRRT was switched off or on. Subsequent CO measurements did not depend on the CRRT status. Interrupting CRRT before measuring CO is not generally recommended, however, if interrupted, it is crucial to wait for blood temperature to reach a steady state before initiating the first measurements.