Raj D S, Tobe S W, Saiphoo C S, Manuel M A
Division of Nephrology, Sunnybrook Health Science Centre, North York, Ontario, Canada.
Int J Artif Organs. 1998 Jun;21(6):328-34.
Determining adequacy of dialysis has remained a problem for the nephrologist despite the results of the National Cooperative Dialysis Study published more than 20 years ago. Urea Kinetics Modelling (UKM) which requires computer data entry is time-consuming for the dialysis staff but is the only method that has been rigorously studied. Furthermore, it is unclear today what value of Kt/V represents ideal dialysis; the technique is subject to a number of errors associated with estimation of dialyser clearance (K) and volume of distribution of urea (V) but it is useful for calculating protein catabolic rate (PCR). Methods that use urea reduction ratios (URR) is widely used because it is simpler but not always accurate and suffer from an inability to calculate PCR. Direct dialysis quantification (DDQ) can overcome a number of these problems but it is too cumbersome for routine use. Simpler methods to determine dialysateside kinetics have the advantage of solving a number of these problems and also facilitate the calculation of PCR to determine the patient's nutritional state. In our study we have demonstrated that by taking two dialysate samples at the beginning and at the end of dialysis (2-DSM), it is possible to determine total urea removal (TUR) which is equivalent to DDQ. By taking blood samples after dialysis and before the next dialysis, it is possible to calculate the total urea generated (TUG). The ratio of TUR/TUG will provide an index of dialysis which places emphasis on removal of solute that has accumulated in the inter-dialytic interval thus re-establishing a state of equilibrium. We refer to this index as the Mass Balance Index (MBI). The MBI is also useful in helping to identify those patients whose PCR is inadequate since the mean MBI for patients with an nPCR <0.8 was 0.93 +/- 0.03 vs 1.08 +/- 0.02 in those with a PCR >0.8. In these two groups of patients the Kt/V was not significantly different, 1.49 +/- 0.07 vs 1.53 +/- 0.06, p -0.64. We suggest that the emphasis for adequacy of dialysis should shift away from Kt/V to maintaining a state of equilibrium by removing the solutes that accumulate between dialysis and by identifying those patients with an inadequate PCR.
尽管20多年前就公布了全国合作透析研究的结果，但确定透析充分性一直是肾病学家面临的一个问题。尿素动力学建模（UKM）需要计算机录入数据，对透析工作人员来说很耗时，但它是唯一经过严格研究的方法。此外，如今尚不清楚Kt/V的何种数值代表理想透析；该技术存在一些与透析器清除率（K）和尿素分布容积（V）估计相关的误差，但它对计算蛋白质分解代谢率（PCR）很有用。使用尿素清除率（URR）的方法被广泛应用，因为它更简单，但并不总是准确，且无法计算PCR。直接透析定量（DDQ）可以克服其中一些问题，但日常使用过于繁琐。更简单的测定透析液侧动力学的方法具有解决其中一些问题的优势，还便于计算PCR以确定患者的营养状况。在我们的研究中，我们证明了通过在透析开始时和结束时采集两份透析液样本（二维样本法），可以确定总尿素清除量（TUR），它等同于DDQ。通过在透析后和下次透析前采集血样，可以计算总尿素生成量（TUG）。TUR/TUG的比值将提供一个透析指标，该指标强调清除透析间期积累的溶质，从而重新建立平衡状态。我们将这个指标称为质量平衡指数（MBI）。MBI在帮助识别那些PCR不足的患者方面也很有用，因为nPCR<0.8的患者的平均MBI为0.93±0.03，而PCR>0.8的患者为1.08±0.02。在这两组患者中，Kt/V没有显著差异，分别为1.49±0.07和1.53±0.06，p = 0.64。我们建议，透析充分性的重点应从Kt/V转移到通过清除透析期间积累的溶质并识别那些PCR不足的患者来维持平衡状态。
