Indicator amount, temperature, and intrinsic cardiac output affect thermodilution cardiac output accuracy and reproducibility
Indicator amount, temperature, and intrinsic cardiac output affect thermodilution cardiac output accuracy and reproducibility
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指标量、温度和内在心输出量影响热稀释心输出量的准确性和再现性
DOI：
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发表时间：
1993
影响因子：
8.8
通讯作者：
Gail Y. Sakuma
中科院分区：
文献类型：
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作者：
L. Renner;M. Morton;Gail Y. Sakuma
目的测定5 mL室温、10 mL室温、5 mL冰和10 mL冰注射液4种热稀释指示剂在临床相关流速下的准确度和重现性。设计准实验研究。单位：某医科大学动物研究实验室。对象6只未交配的西方品种母羊。干预数据收集自六只装有升主动脉电磁流量探头和下腔静脉封堵器的母羊。心输出量通过下腔静脉阻断和异丙肾上腺素输注来控制。分别在高、低心排血量水平下对四种热稀释指示剂进行测试，并与电磁流量计测量心排血量进行比较。测量和主要结果指示剂量由注射液体积和注射液与血液之间的温差确定。使用5 mL室温注射液作为参比品，10 mL室内含有2 x、5 mL冷冻2.1 x和10 mL冷冻4.1 x 5 mL室温注射液的指示量。在1.5至15.7 L/min的流量范围内，对每种注射液进行了约210次同时热稀释和电磁流量测量。对于整个心输出量范围，不存在系统误差。然而，10 mL冷冻注射液组的r2值（0.92）大于（p <0.05）5 mL冷冻注射液组的r2值（0.79），而10 mL室温组的r2值为0.79，5 mL室温组为0.49。在<4.7 L/min的流速下，注射液之间的r2没有差异，但减少的指示剂量进展高估了输出（p <0.05），5 mL室温组达到21%。在流速>7.7 L/min时，10 mL冷冻组的r2值（.81）大于（p < .05）5 mL冷冻组的r2值（.45），而10 mL室温组的r2值为.24，5 mL室温组的r2值为.08。不存在系统误差。结论：在低心输出量水平，减少指标损害准确性，但不重复性，这一现象可能与指标损失。在高心输出率下，指示剂降低会损害再现性。这种现象可能与低信噪比有关。热稀释指示剂量应根据输出范围进行调整。(Crit护理医学1993; 21：586-597）
ObjectiveTo determine the accuracy and reproducibility of four thermodilution indicators (5-mL room temperature, 10-mL room temperature, 5-mL iced, and 10-mL iced injectates) at clinically relevant flow rates. DesignQuasi-experimental study. SettingAnimal research laboratory of a health sciences university. SubjectsSix virgin western-breed ewes. InterventionsData were collected from six ewes that had ascending aorta electromagnetic flow probes and inferior vena cava occluders. Cardiac output was manipulated by inferior vena cava occlusion and isoproterenol infusion. Four thermodilution indicators were tested at high and low levels of cardiac output and compared with the electromagnetic flowmeter measurements of cardiac output. Measurements and Main ResultsThe indicator amounts were determined from both injectate volume and temperature difference between the injectate and blood. Using 5-mL room temperature injectate as a reference, 10-mL room contained 2 x, 5-mL iced 2.1 x, and 10-mL iced 4.1 x the indicator amount of 5-mL room temperature injectate. Approximately 210 simultaneous thermodilution and electromagnetic flow measurements were made for each injectate over a flow range of 1.5 to 15.7 L/min. For the entire cardiac output range, systematic error was not present. However, the r2 value (.92) for the 10-mL iced injectate group was greater (p < .05) than that value (.79) for the 5-mL iced injectate group, while r2 values were .79 for the 10-mL room temperature group and .49 for the 5-mL room temperature group. At flow rates of <4.7 L/min, r2 was not different among injectates, but reduced indicator amounts progress vely overestimated output (p < .05), reaching 21% for the 5-mL room temperature group. At flow rates of >7.7 L/min, the r2 value (.81) for the 10-mL iced group was greater (p < .05) than that value (.45) for the 5-mL iced group, while r2 values were .24 for the 10-mL room temperature group and .08 for the 5-mL room temperature group. Systematic error was not present. ConclusionsAt low cardiac output levels, reduced indicator impairs accuracy but not reproducibility, a phenomenon that is perhaps related to indicator loss. At high cardiac output rates, reduced indicator impairs reproducibility. This phenomenon is probably related to low signal-to-noise ratio. Thermodilution indicator amounts should be tailored to the output range. (Crit Care Med 1993; 21:586–597)