Hahn Robert G
Karolinska institutet at Danderyds sjukhus (KIDS), 171 77 Stockholm, Sweden.
Microvasc Res. 2024 Jan;151:104599. doi: 10.1016/j.mvr.2023.104599. Epub 2023 Sep 1.
Kinetic analysis of fluid volume shifts can identify two interstitial fluid compartments with different turnover rates, but how they are connected to the bloodstream is unknown.
Retrospective data were retrieved from 217 experiments where 1.5 L of Ringer's solution (mean) had been administered by intravenous infusion over 30 min to awake and anesthetized humans (mean age 40 years). Urinary excretion and hemoglobin-derived plasma dilution served as input variables in a volume kinetic analysis using mixed models software. Possible modes of connection between the two interstitial fluid compartments and the bloodstream were judged by covariance analysis between kinetic rate constants, physiological variables, and time factors.
The return flow of already distributed fluid to the plasma via a fast-exchange interstitial compartment was inhibited ongoing infusion of fluid (-38 %), which was probably due to increase of the venous pressure during volume loading. Ongoing infusion also greatly retarded the entrance of fluid to the slow-exchange compartment (-85 %), which suggests that infused Ringer's first had to enter the fast-exchange compartment. A high mean arterial pressure markedly increased the urine output and, to a lesser degree, also the rate of entrance of fluid to the fast-exchange compartment. Moreover, a high blood hemoglobin concentration retarded the rate of entrance of fluid to the fast-exchange compartment.
The fast-exchange but not the slow-exchange interstitial fluid compartment was affected by intravascular events, which suggests that only the fast-exchange compartment is directly connected to the circulating blood.
对液体容量变化的动力学分析可以识别出两个具有不同周转率的间质液腔室，但它们与血流的连接方式尚不清楚。
从217项实验中检索回顾性数据，在这些实验中，向清醒和麻醉的人类（平均年龄40岁）静脉输注1.5升（平均）林格氏液，持续30分钟。在使用混合模型软件进行的容量动力学分析中，将尿排泄和血红蛋白衍生的血浆稀释作为输入变量。通过动力学速率常数、生理变量和时间因素之间的协方差分析来判断两个间质液腔室与血流之间可能的连接方式。
通过快速交换间质腔室使已分布的液体回流到血浆的过程在持续输注液体期间受到抑制（-38%），这可能是由于容量负荷期间静脉压升高所致。持续输注还极大地延缓了液体进入缓慢交换腔室的速度（-85%），这表明输注的林格氏液首先必须进入快速交换腔室。高平均动脉压显著增加尿量，并且在较小程度上也增加了液体进入快速交换腔室的速度。此外，高血血红蛋白浓度延缓了液体进入快速交换腔室的速度。
快速交换而非缓慢交换的间质液腔室受血管内事件影响，这表明只有快速交换腔室直接与循环血液相连。
