Tzamaloukas A H, Murata G H, Malhotra D
New Mexico Veterans Affairs Health System, and the Department of Medicine, University of New Mexico School of Medicine, Albuquerque 87108, USA.
ASAIO J. 2000 Jan-Feb;46(1):76-80. doi: 10.1097/00002480-200001000-00020.
In peritoneal dialysis (PD), small solute clearances are normalized by body water (V) and body surface area (BSA). The purpose of this study was to identify if V or BSA produced stronger associations between body size and normalized clearances. We studied the relationship between four size indicators (V, BSA, height, and weight) and either peritoneal urea clearance normalized to V (Kt/V(ur)) and BSA (C(ur)) or creatinine clearance normalized to V (Kt/V(cr)) and BSA (C(cr)). A total of 613 clearance studies were performed in subjects on continuous ambulatory peritoneal dialysis (CAPD) with four daily exchanges and a 2 L fill volume. As size increased, the normalized peritoneal clearances decreased in a nonlinear fashion (regression: y = b0 + b1x(-1), where x is a size indicator and y is a normalized clearance). Significant (p < 0.001) negative correlations were found between each normalized clearance and each size indicator. However, in each case, the correlation was higher when V, rather than BSA, was used. For example, BSA correlated more closely with K/V(ur)(-0.660) than C(ur)(-0.556), and also with Kt/V(cr)(-0.579) than C(cr)(-0.446). Normalized clearances are smaller in large subjects on CAPD because one mathematic determinant of the clearance, the drain volume (Dv) normalized by V (Dv/V) or BSA (DV/BSA), decreases as size increases. The relationship between Dv/V or Dv/BSA and the size indicators was studied by the same nonlinear regression model. The correlations of the size indicators with Dv/V were also consistently higher than the corresponding correlations with Dv/BSA. In subjects who were on the same PD schedule, the dependence of clearances on size was consistently higher when V, rather than BSA, was the normalizing parameter. Because prescription of the dose of PD is based on body size, there is a practical advantage by using V as the sole normalizing parameter for both urea and creatinine clearance.
在腹膜透析（PD）中，小分子溶质清除率通过机体水分（V）和体表面积（BSA）进行标准化。本研究的目的是确定V或BSA在体型与标准化清除率之间产生的关联更强。我们研究了四个体型指标（V、BSA、身高和体重）与经V标准化的腹膜尿素清除率（Kt/V(ur)）和经BSA标准化的腹膜尿素清除率（C(ur)），或经V标准化的肌酐清除率（Kt/V(cr)）和经BSA标准化的肌酐清除率（C(cr)）之间的关系。对总共613例接受持续性非卧床腹膜透析（CAPD）且每日进行四次交换、每次灌入量为2 L的患者进行了清除率研究。随着体型增大，标准化腹膜清除率呈非线性下降（回归方程：y = b0 + b1x(-1)，其中x为体型指标，y为标准化清除率）。在每个标准化清除率与每个体型指标之间均发现显著（p < 0.001）负相关。然而，在每种情况下，使用V时的相关性高于使用BSA时。例如，BSA与K/V(ur)（-0.660）的相关性比与C(ur)（-0.556）的相关性更密切，与Kt/V(cr)（-0.579）的相关性也比与C(cr)（-0.446）的相关性更密切。在接受CAPD的体型较大的患者中，标准化清除率较低，这是因为清除率的一个数学决定因素，即经V标准化的引流体积（Dv）（Dv/V）或经BSA标准化的引流体积（DV/BSA），会随着体型增大而减小。通过相同的非线性回归模型研究了Dv/V或Dv/BSA与体型指标之间的关系。体型指标与Dv/V的相关性也始终高于与Dv/BSA的相应相关性。在接受相同腹膜透析方案的患者中，当以V而非BSA作为标准化参数时，清除率对体型的依赖性始终更高。由于腹膜透析剂量的处方是基于体型的，因此将V作为尿素和肌酐清除率的唯一标准化参数具有实际优势。
