Pastan S, Colton C
Department of Medicine, Indiana University School of Medicine, Indianapolis.
ASAIO Trans. 1989 Jul-Sep;35(3):247-50. doi: 10.1097/00002480-198907000-00022.
Concern exists that increasingly high-efficiency dialysis will result in large urea gradients between intracellular and extracellular compartments (VI, VE) leading to large amounts of extracellular volume depletion (delta VE) and hemodynamic instability induced by rapid water flow from VE to VI. The authors investigated this question with a two-compartment model that provided estimates of VI, VE, and osmotically active intracellular and extracellular urea and nonurea concentrations during hemodialysis. The authors found that the urea gradient-induced transcellular water shift is only a very small fraction of VE, even with high urea clearance and short hemodialysis time. The net water shift was small because the urea and nonurea transcellular osmolar gradients were of similar magnitudes but in offsetting directions.
人们担心，越来越高效的透析会导致细胞内和细胞外隔室（VI，VE）之间出现较大的尿素梯度，从而导致大量细胞外液体积减少（δVE）以及由于水从VE快速流向VI而引起的血液动力学不稳定。作者使用一个双室模型研究了这个问题，该模型提供了血液透析期间VI、VE以及具有渗透活性的细胞内和细胞外尿素及非尿素浓度的估计值。作者发现，即使在高尿素清除率和短血液透析时间的情况下，尿素梯度诱导的跨细胞水转移也只是VE的极小一部分。净水转移量很小，因为尿素和非尿素跨细胞渗透梯度大小相似但方向相反。
