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首页> 外文期刊>American Journal of Physiology >Transit time dispersion in pulmonary and systemic circulation: effects of cardiac output and solute diffusivity.
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Transit time dispersion in pulmonary and systemic circulation: effects of cardiac output and solute diffusivity.

机译：肺和系统循环中的传播时间分散：心输出量和溶质扩散性的影响。

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摘要

We present an in vivo method for analyzing the distribution kinetics of physiological markers into their respective distribution volumes utilizing information provided by the relative dispersion of transit times. Arterial concentration-time curves of markers of the vascular space [indocyanine green (ICG)], extracellular fluid (inulin), and total body water (antipyrine) measured in awake dogs under control conditions and during phenylephrine or isoproterenol infusion were analyzed by a recirculatory model to estimate the relative dispersions of transit times across the systemic and pulmonary circulation. The transit time dispersion in the systemic circulation was used to calculate the whole body distribution clearance, and an interpretation is given in terms of a lumped organ model of blood-tissue exchange. As predicted by theory, this relative dispersion increased linearly with cardiac output, with a slope that was inversely related to solute diffusivity. The relative dispersion of the flow-limited indicator antipyrine exceeded that of ICG (as a measure of intravascular mixing) only slightly and was consistent with a diffusional equilibration time in the extravascular space of approximately 10 min, except during phenylephrine infusion, which led to an anomalously high relative dispersion. A change in cardiac output did not alter the heterogeneity of capillary transit times of ICG. The results support the view that the relative dispersions of transit times in the systemic and pulmonary circulation estimated from solute disposition data in vivo are useful measures of whole body distribution kinetics of indicators and endogenous substances. This is the first model that explains the effect of flow and capillary permeability on whole body distribution of solutes without assuming well-mixed compartments.
机译：我们提出了一种体内方法，用于利用通过时间的相对分散所提供的信息，将生理标志物的分布动力学分析成它们各自的分布体积。通过循环分析法分析了清醒犬在对照条件下以及去氧肾上腺素或异丙肾上腺素输注期间测量的血管空间[吲哚菁绿（ICG）]，细胞外液（菊粉）和全身水（安替比林）标志物的动脉浓度-时间曲线。估计整个体循环和肺循环中转运时间的相对离散。全身循环中的传播时间分散度用于计算全身分布清除率，并根据血液组织交换的集总器官模型进行解释。如理论所预测的，该相对色散随心输出量线性增加，其斜率与溶质扩散率成反比。限流指示剂安替比林的相对分散仅略微超过了ICG（作为血管内混合的量度），并且与大约10分钟的血管外空间中的扩散平衡时间相符，除了输注去氧肾上腺素期间导致相对较高的相对色散。心输出量的变化并没有改变ICG的毛细管转运时间的异质性。结果支持这样一种观点，即根据体内溶质分布数据估算的全身和肺循环中运输时间的相对分散是衡量指标和内源性物质全身分布动力学的有用手段。这是第一个解释流量和毛细管渗透率对溶质的整体分布的影响的模型，而无需假定混合均匀。

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