使用双热敏电阻导管系统提高热稀释法心输出量测量的准确性和精确性。

Lehmann K G, Platt M S

Section of Cardiology, University of Washington School of Medicine, Seattle, USA.

J Am Coll Cardiol. 1999 Mar;33(3):883-91. doi: 10.1016/s0735-1097(98)00639-1.

OBJECTIVES

To assess whether thermodilution cardiac output determination based on measurement of injectate temperature in vivo leads to more accurate and precise estimates and to study the influence of chilled injectate on test performance.

BACKGROUND

Cardiac output measurement via right heart catheterization is used extensively for hemodynamic evaluation in a variety of diagnostic, perioperative and critical care settings. Maximizing accuracy is essential for optimal patient care.

METHODS

This prospective study of 960 thermodilution cardiac output measurements was conducted using conventional and dual thermistor techniques. Specialized dual thermistor right heart catheters were constructed using a second thermistor positioned to measure injectate temperature in vivo just prior to entry into the right atrium. To eliminate interinjection variability, a custom set-up was developed that permitted output measurement using both techniques simultaneously. Both ambient temperature injections and cooled injections were investigated.

RESULTS

The dual thermistor technique demonstrated significantly less measurement variability than the conventional technique for both ambient temperature (precision = 0.41 vs. 0.55 L/min, p < 0.001) and cooled (precision = 0.35 vs. 0.43 L/min, p = 0.01) injections. Similarly, the average range of cardiac output values obtained during five sequential injections in each patient was less using the dual thermistor approach (1.05 vs. 1.55 L/min, p < 0.001). The use of cooled injectate reduced the mean error of the dual thermistor technique but actually increased the mean error of the conventional technique. Even with ambient temperature injections, injectate warming during catheter transit varied considerably and unpredictably from injection to injection (2 SD range = -0.22 to 5.74 degrees C). Conventional ambient temperature and cooled measurements significantly overestimated Fick cardiac output measurements by 0.32 and 0.50 L/min, respectively (p < 0.001). In contrast, dual thermistor measurements were statistically similar (-0.08 and -0.08 L/min, p = 0.34) to Fick measurements.

CONCLUSIONS

This new dual thermistor approach results in a significant improvement in both precision and accuracy of thermodilution cardiac output measurement.

目的

评估基于体内注射液温度测量的热稀释法心输出量测定是否能得出更准确和精确的估计值，并研究冷注射液对测试性能的影响。

背景

通过右心导管插入术测量心输出量在各种诊断、围手术期和重症监护环境中广泛用于血流动力学评估。将准确性最大化对于优化患者护理至关重要。

方法

本前瞻性研究对960次热稀释法心输出量测量采用了传统技术和双热敏电阻技术。特制的双热敏电阻右心导管通过在即将进入右心房之前放置第二个热敏电阻来测量体内注射液温度。为消除注射间的变异性，开发了一种定制装置，允许同时使用两种技术进行输出测量。研究了环境温度注射和冷注射。

结果

对于环境温度注射（精密度 = 0.41 vs. 0.55 L/分钟，p < 0.001）和冷注射（精密度 = 0.35 vs. 0.43 L/分钟，p = 0.01），双热敏电阻技术显示出比传统技术显著更小的测量变异性。同样，在每位患者的五次连续注射期间，采用双热敏电阻方法获得的心输出量值的平均范围更小（1.05 vs. 1.55 L/分钟，p < 0.001）。使用冷注射液降低了双热敏电阻技术的平均误差，但实际上增加了传统技术的平均误差。即使是环境温度注射，导管传输过程中注射液的升温在每次注射之间也有很大差异且不可预测（2个标准差范围 = -0.22至5.74摄氏度）。传统的环境温度测量和冷测量分别显著高估菲克心输出量测量值0.32和0.50 L/分钟（p < 0.001）。相比之下，双热敏电阻测量与菲克测量在统计学上相似（-0.08和 -0.08 L/分钟，p = 0.34）。