Department of Anaesthesiology, Emergency and Critical Care Medicine, University of Göttingen, Göttingen, Germany.
Minerva Anestesiol. 2012 Mar;78(3):315-21.
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.
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®).
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).
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.
急性肾衰竭（ARF）是危重病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。导致 ARF 的因素，如感染性休克和血流动力学不稳定，需要进行扩展的血流动力学监测，同时使用 CRRT 和心输出量测量是很常见的。有鉴于此，有必要对 CRRT 和热稀释法心输出量测量之间的相互作用进行系统分析。心输出量（CO）在危重病患者中通常使用基于热稀释的方法进行测量。这些方法准确，但测量结果会受到指示剂体积变化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，因此我们研究了它对基于热稀释的 CO 测量的影响。
研究了 32 例同时接受 CRRT 和 CO 监测的重症监护患者。在 CRRT 期间，首先通过冷盐水的五次推注测量五次血流动力学参数。在关闭 CRRT 后进行五次进一步测量，在重新开始 CRRT 后进行最后五次测量。在使用肺动脉导管的患者中进行了 50 次测量系列，在使用经肺热稀释法（PiCCO®）的患者中进行了 25 次测量系列。
在每次切换 CRRT 关闭或打开后进行的第一次测量中，与平均值偏差最大。当排除这些测量值后，有无 CRRT 时的平均 CO 值差异显著，但差异<7%（P<0.05）。
只有在切换 CRRT 关闭或打开后立即观察到明显的测量误差。随后的 CO 测量值并不取决于 CRRT 状态。如果要在测量 CO 之前中断 CRRT，则不建议中断，但中断后，在开始第一次测量之前，必须等待血液温度达到稳定状态，这一点至关重要。
