Sherman R A, Kapoian T
Department of Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick 08903, USA.
Am J Kidney Dis. 1997 Apr;29(4):479-89. doi: 10.1016/s0272-6386(97)90328-0.
When accurate, non-urea-based methods of measuring recirculation are used, recirculation is usually absent in arteriovenous (AV) accesses. When urea-based methods are used to measure recirculation in AV accesses, falsely elevated recirculation rates are common. These errors are due to AV and venovenous disequilibrium (peripheral vein method), delayed systemic sampling (two-needle methods), and errors in urea measurement (all methods). The literature suggests that recirculation in central venovenous (CV) catheters is approximately 5%. The methods used for these determinations have all been urea based. However, there are few theoretical problems in using urea-based measurements for measuring recirculation in this setting, making it more likely that these values are accurate. When hemodialysis via CV and AV accesses are compared, equilibrated Kt/V values differ significantly for the same single-pool Kt/V when 15-second postdialysis blood urea nitrogen values are used for modeling, but differ minimally when 2-minute postdialysis samples are used. The impact of transient retrograde blood flow in the superior vena cava on recirculation and whether dialysis efficiency is influenced by the exact site of CV catheter placement (superior vena cava v right atrium) is uncertain.
当使用准确的、非基于尿素的方法测量再循环时，动静脉（AV）通路通常不存在再循环。当使用基于尿素的方法测量AV通路的再循环时，再循环率假性升高很常见。这些误差是由于动静脉和静脉-静脉失衡（外周静脉法）、全身采样延迟（双针法）以及尿素测量误差（所有方法）导致的。文献表明，中心静脉-静脉（CV）导管的再循环率约为5%。用于这些测定的方法均基于尿素。然而，在这种情况下使用基于尿素的测量方法测量再循环几乎没有理论问题，这使得这些值更有可能是准确的。当比较通过CV和AV通路进行血液透析时，对于相同的单池Kt/V，若使用透析后15秒的血尿素氮值进行建模，平衡后的Kt/V值有显著差异，但使用透析后2分钟的样本时差异最小。上腔静脉中短暂的逆向血流对再循环的影响以及透析效率是否受CV导管放置的确切部位（上腔静脉与右心房）影响尚不确定。
