Maduell F, Garcia-Valdecasas J, Garcia H, Hdez-Jaras J, Sigüenza F, del Pozo C, Giner R, Moll R, Garrigos E
Nephrology Department, Hospital General de Castellón, Spain.
Nephron. 1998;78(2):143-7. doi: 10.1159/000044902.
An American National Study shows that survival benefits from higher dialysis doses appear to be present up to a Kt/V level of 1.3 or a urea reduction ratio (URR) of 70%. The effect of increasing dialysis efficiency magnified urea rebound and the error in URR determinations. Several formulas have been developed to calculate URR considering the urea rebound (URRr). Smye and coworkers have proposed a method whereby the equilibrated blood urea nitrogen is predicted by additional intradialytic urea sample. Maduell and colleagues, based on analysis of postdialysis urea rebound, have proposed a method whereby the urea rebound is predicted. To compare measured URRr to estimated by Smye and Maduell formulas, 384 patients were studied, 211 males and 173 females, who received a dialysis session with their habitual parameters. Measurements of plasma urea concentration were obtained at the beginning, 90-100 min following the start of dialysis, at the end, and 45 min after dialysis. The postdialysis urea rebound was 22.4+/-9.7%. The urea kinetic model Kt/V was 1.365+/-0.26, and Kt/Vr was 1.14+/-0.23. URR was 68.7+/-6.6%, and when it was calculated with urea rebound, it decreased to 61.9+/-7.4%. The URRr correlated with calculations by Smye and Maduell formulas: 60.7+/-8.4 (r = 0.722, p < 0.001) and 61.8+/-6.6 (r = 0.933, p < 0.001), respectively. The precision of estimated limits of agreement and percentage of error by Bland and Altman analysis show that URRr estimated Maduell formula could be used in place of the URRr. Otherwise, the degree of agreement of the Smye method was not clinically acceptable. In conclusion, our results led us to suggest that in actual dialysis, the use of URR is not adequate for delivered hemodialysis dose, and URRr should be used. URRr estimated by Maduell formula could be a simple and accurate method for use in clinical practice. The recommended dialysis dose by the American National Study of URR of 70% could correspond, considering urea rebound, to Kt/Vr 1.18 or URRr of 64%.
一项美国全国性研究表明，透析剂量增加带来的生存益处似乎在Kt/V水平达到1.3或尿素清除率（URR）达到70%之前都存在。提高透析效率的作用放大了尿素反跳以及URR测定中的误差。已经开发了几种考虑尿素反跳（URRr）来计算URR的公式。斯迈（Smye）及其同事提出了一种方法，通过透析期间额外的尿素样本预测平衡后的血尿素氮。马杜埃尔（Maduell）及其同事基于对透析后尿素反跳的分析，提出了一种预测尿素反跳的方法。为了比较测量的URRr与用斯迈公式和马杜埃尔公式估算的值，对384例患者进行了研究，其中男性211例，女性173例，这些患者按照其惯常参数接受了一次透析治疗。在透析开始时、开始后90 - 100分钟、结束时以及透析后45分钟测量血浆尿素浓度。透析后尿素反跳为22.4±9.7%。尿素动力学模型Kt/V为1.365±0.26，Kt/Vr为1.14±0.23。URR为68.7±6.6%，当考虑尿素反跳计算时，其降至61.9±7.4%。URRr与用斯迈公式和马杜埃尔公式计算的值相关：分别为60.7±8.4（r = 0.722，p < 0.001）和61.8±6.6（r = 0.933，p < 0.001）。通过布兰德 -奥尔特曼（Bland and Altman）分析得出的一致性估计限的精度和误差百分比表明，用马杜埃尔公式估算的URRr可替代测量的URRr。否则，斯迈方法的一致性程度在临床上不可接受。总之，我们的结果使我们建议，在实际透析中，使用URR来评估实际的血液透析剂量并不合适，而应使用URRr。用马杜埃尔公式估算的URRr可能是一种适用于临床实践的简单且准确的方法。考虑到尿素反跳，美国全国性研究推荐的70%的URR透析剂量可能相当于Kt/Vr为1.18或URRr为64%。
