Sources of Error in Noninvasive Pulmonary Blood Flow Measurements by Partial Rebreathing: A Computer Model Study
Sources of Error in Noninvasive Pulmonary Blood Flow Measurements by Partial Rebreathing: A Computer Model Study
复制标题
部分再呼吸无创肺血流量测量的误差来源：计算机模型研究
DOI：
10.1097/00000542-200304000-00014
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发表时间：
2003
期刊：
影响因子：
8.8
通讯作者：
A. Barry Baker
中科院分区：
文献类型：
--
作者：
J. S. Yem;Yongquan Tang;Martin J. Turner;A. Barry Baker
背景部分重复呼吸是一种无创的肺血流量测量方法。本研究利用一个健康的70公斤的成年男性心肺系统的综合数学模型，检查由部分再呼吸技术产生的系统误差。方法该模型通过分支呼吸树模拟潮气呼吸，并结合了对肺组织质量的二氧化碳动力学、血管传输延迟、多个身体隔室和真实的血气解离曲线的影响。进行了4项研究：（1）标准条件下产生的误差，（2）再循环的影响，（3）肺泡-近端气道二氧化碳分压（Pco 2）差异的影响，以及（4）再呼吸时间的影响。结果当模拟的PBF在3 ~ 6 l/min时，系统误差小于10%，当模拟的PBF为2 l/min时，系统误差约为35%。在14 l/min时，PBF被低估了约40%。在PBF大于6 l/min时，再循环导致约60%的系统误差，肺泡-近端气道差异导致约20%，肺泡-动脉差异导致约20%。对于PBF大于6 l/min，50 s的标准再呼吸时间被证明是过多的。在PBF小于3 l/min时，错误是由不充分的再呼吸时间和肺泡动脉梯度引起的。结论部分重复呼吸心输出量测量的系统误差是多方面的。我们的模拟表明，可以减少错误，通过使用可变的再呼吸时间，这应该增加在低PBF，使准平衡的肺泡可以实现和减少在高PBF，以减少再循环的影响。
Background Partial rebreathing is a noninvasive method for measuring pulmonary blood flow (PBF). This study examines the systematic errors produced by the partial rebreathing technique utilizing a comprehensive mathematical model of the cardiorespiratory system of a healthy, 70-kg adult male. Methods The model simulates tidal breathing through a branched respiratory tree and incorporates the effects on carbon dioxide dynamics of lung tissue mass, vascular transport delays, multiple body compartments, and realistic blood–gas dissociation curves. Four studies were performed: (1) errors produced under standard conditions, (2) effects of recirculation, (3) effects of alveolar–proximal airway partial pressure of carbon dioxide (Pco2) differences, and (4) effects of rebreathing time. Results Systematic errors are less than 10% when the simulated PBF is between 3 and 6 l/min. At 2 l/min, PBF is overestimated by approximately 35%. At 14 l/min, PBF is underestimated by approximately 40%. At PBF of greater than 6 l/min, recirculation causes approximately 60% of the systematic error, alveolar–proximal airway differences cause approximately 20%, and alveolar–arterial differences cause approximately 20%. The standard rebreathing time of 50 s is shown to be excessive for PBF of greater than 6 l/min. At PBF of less than 3 l/min, errors are caused by inadequate rebreathing time and alveolar–arterial gradients. Conclusions Systematic errors in partial rebreathing cardiac output measurements have multiple causes. Our simulations suggest that errors can be reduced by using a variable rebreathing time, which should be increased at low PBF so that quasi-equilibrium in the alveoli can be achieved and decreased at high PBF to reduce the effects of recirculation.