Ohashi Yasushi, Sakai Ken, Hase Hiroki, Joki Nobuhiko
Department of Nephrology, Sakura Medical Center, Toho University, Chiba, Japan.
Department of Nephrology, School of Medicine, Faculty of Medicine, Toho University, Tokyo, Japan.
Semin Dial. 2018 Nov;31(6):551-556. doi: 10.1111/sdi.12721. Epub 2018 Jun 6.
Fluid volume overload is common and is associated with adverse outcomes in hemodialysis patients. Practicing physicians individually manage fluid volume balance in their dialysis patients according to blood pressure, interdialytic weight gain, cardiac function, nutritional status, and other comorbidities. However, accurate assessment of fluid volume status remains a concern. Indicators of dry weight target have been explored further with newer concepts and technologies. In general, total body water comprises approximately 50%-60% of adult body weight (range, 45%-75%), and water comprises 73.3% of lean body mass. The standard hydration status between intracellular water and extracellular water is maintained at a ratio of 62:38 in healthy adults, which, however, is influenced universally by body cell volume driven by age and muscle mass. Fluid volume imbalance in dialysis patients also is characterized primarily by decreased body cell mass associated with aging and muscle attenuation, as well as excess extracellular water content associated with sodium retention, which may be associated with the reserve capacity for volume overload. Indeed, dialysis patients with a leaner body mass have a higher prevalence of hypertension, poorer hypertension control, and greater left ventricular hypertrophy. Understanding of these body composition changes by aging and sarcopenia can aid clinical decision making in the dry weight assessments in dialysis patients. Advising patients with consistently high interdialytic weight gain to practice salt restriction and providing appropriate nutritional support for malnourished patients with downward trajectory in their dry weight would be of great help to achieve optimal fluid volume status.
液体容量超负荷在血液透析患者中很常见，且与不良预后相关。执业医师会根据血压、透析间期体重增加、心功能、营养状况及其他合并症，分别管理透析患者的液体容量平衡。然而，准确评估液体容量状态仍是一个问题。随着新的概念和技术的出现，对干体重目标的指标进行了进一步探索。一般来说，成年人体重的约50%-60%由总体水组成（范围为45%-75%），水占去脂体重的73.3%。在健康成年人中，细胞内水和细胞外水之间的标准水合状态维持在62:38的比例，但这一比例普遍受到年龄和肌肉量驱动的体细胞体积的影响。透析患者的液体容量失衡主要表现为与衰老和肌肉萎缩相关的体细胞质量减少，以及与钠潴留相关的细胞外水含量过多，这可能与容量超负荷的储备能力有关。事实上，体型较瘦的透析患者高血压患病率更高，高血压控制较差，左心室肥厚更严重。了解衰老和肌肉减少症引起的这些身体成分变化有助于透析患者干体重评估中的临床决策。建议透析间期体重持续增加的患者限制盐摄入，并为干体重呈下降趋势的营养不良患者提供适当的营养支持，这将有助于实现最佳的液体容量状态。
