Sombolos K, Natse T, Zoumbaridis N, Mavromatidis K, Karagianni A, Scandalos J, Fitili C
Renal Unit, G. Papanikolaou General Hospital, Thessaloniki, Greece.
Am J Kidney Dis. 1996 May;27(5):673-9. doi: 10.1016/s0272-6386(96)90102-x.
To elucidate the intradialytic urea concentration gradients, we examined 26 hemodialysis patients wearing a double-lumen central venous catheter during their first or second fistula-punctured dialysis session. In 17 patients (group A), after 60 and 240 minutes of treatment with a mean blood flow of 196.4 +/- 9.9 mL/min, blood urea nitrogen (BUN) was measured in blood samples taken simultaneously from the central venous catheter, a vein in the arm opposite the access site, and the arterial and venous lines of the dialyzer. In 16 patients (group B), after 60 minutes of treatment with a mean blood flow rate of 197.5 +/- 12.3 mL/min, BUN was measured in blood samples taken from the dialyzer arterial line and then, after decreasing the blood flow to 50 to 60 mL/min for 1 minute, in samples taken from a vein in the arm opposite the access site, the central venous catheter, and the dialyzer arterial line. In group A, the mean BUN values in the dialyzer arterial line at 60 and 240 minutes were found to be 3.7% +/- 3.7% and 3.5% +/- 3.4% higher than the corresponding values in the central veins, respectively (P = NS between 60 and 240 minutes). In group B, after 1 minute of low blood flow, this difference was 1.5% +/- 2.4% (P = 0.06 compared with group A). The peripheral veins in group A patients at 60 and 240 minutes had 9.7% +/- 5.2% and 10.9% +/- 5.3% higher BUN values, respectively, compared with the central veins. This difference in group B patients after 1 minute of low blood flow was 6.8% +/- 4.2%. Urea access recirculation rate in group A, calculated by the classical three-samples method, was found to be 7.6% +/- 5.0% at 60 minutes and 9.9% +/- 5.8% at 240 minutes (P = NS). In group B, BUN values in the dialyzer arterial line after 1 minute of low blood flow increased significantly by 3.4% +/- 4.5% (P < 0.01). Our study shows that during conventional hemodialysis with a blood flow rate of 200 mL/min, urea concentration in the central veins is lower than in the dialyzer arterial line. This gradient after 1 minute of low-flow dialysis had a tendency to decrease. At the same time, however, the urea concentration gradient between the peripheral and central veins remained high, indicating that during conventional hemodialysis, intercompartmental disequilibrium plays a significant role in the arteriovenous gradient.
为阐明透析过程中尿素浓度梯度，我们检查了26例在首次或第二次动静脉内瘘穿刺透析治疗期间佩戴双腔中心静脉导管的血液透析患者。在17例患者（A组）中，以平均血流量196.4±9.9 mL/min治疗60分钟和240分钟后，同时从中心静脉导管、内瘘对侧手臂的静脉以及透析器的动脉和静脉管路采集血样，测定血尿素氮（BUN）。在16例患者（B组）中，以平均血流量197.5±12.3 mL/min治疗60分钟后，从透析器动脉管路采集血样测定BUN，然后将血流量降至50至60 mL/min持续1分钟后，再从内瘘对侧手臂的静脉、中心静脉导管和透析器动脉管路采集血样测定BUN。在A组中，发现透析器动脉管路在60分钟和240分钟时的平均BUN值分别比中心静脉的相应值高3.7%±3.7%和3.5%±3.4%（60分钟和240分钟之间P=无显著性差异）。在B组中，低血流量1分钟后，该差异为1.5%±2.4%（与A组相比P=0.06）。A组患者在60分钟和240分钟时外周静脉的BUN值分别比中心静脉高9.7%±5.2%和10.9%±5.3%。B组患者在低血流量1分钟后的该差异为6.8%±4.2%。用经典的三点法计算，A组在60分钟时的尿素再循环率为7.6%±5.0%，在240分钟时为9.9%±5.8%（P=无显著性差异）。在B组中，低血流量1分钟后透析器动脉管路的BUN值显著升高3.4%±4.5%（P<0.01）。我们的研究表明，在血流量为200 mL/min的常规血液透析过程中，中心静脉中的尿素浓度低于透析器动脉管路中的尿素浓度。低流量透析1分钟后的这种梯度有降低的趋势。然而，与此同时，外周静脉和中心静脉之间的尿素浓度梯度仍然很高，这表明在常规血液透析过程中，跨腔室不平衡在动静脉梯度中起重要作用。
