Casino Francesco G, Marshall Mark R
Divisione di Nefrologia e Dialisi, Ospedale Madonna delle Grazie, Matera, Italy.
Nephrol Dial Transplant. 2004 Jun;19(6):1454-66. doi: 10.1093/ndt/gfh218. Epub 2004 Mar 19.
The quantification of dialysis in critically ill acute renal failure (ARF) patients requires a unifying expression that can establish kinetic equivalence amongst patients treated with irregular or frequent intermittent haemodialysis (IHD) schedules or with differing renal replacement therapies. EKRjc is a generalized form of the equivalent urea renal clearance (EKRc), and represents the equivalent continuous urea clearance that will result in the given time-averaged concentration of urea, for the given amount of urea removal. The suitability of EKRjc for the measurement of dialysis dose in this setting is examined.
420 weeks of renal replacement therapy (IHD and continuous renal replacement therapy) were simulated in 15 virtual 'patients' using a variable volume double pool urea kinetic model. Additional data from eight ARF patients were used to exemplify calculations. 1260 EKRjc values were calculated using both formal urea kinetic modelling, as well as a simplified method that requires input of changes in patient fluid state and blood urea nitrogen concentrations over a period of observation, in addition to an initial estimate of patient post-dialysis urea distribution volume (V(T)).
EKRjc is shown to provide a unifying expression of dialysis dose irrespective of IHD schedule or renal replacement therapy. EKRjc is shown to be independent from the assumption of the urea steady state, and intrinsically normalized to patient urea distribution volume to allow dose comparisons between patients of different size. Residual renal urea clearance is easily incorporated where present. EKRjc is easily calculated using the simplified method without the need for iterative urea kinetic modelling. The accuracy of this simplified method is maintained when the initial estimation of V(T) is both 25% greater or smaller than the true value. Calculation of EKRjc is exemplified using the clinical data.
EKRjc is the most suitable urea kinetic expression for the quantification of dialysis in critically ill ARF patients.
对重症急性肾衰竭（ARF）患者的透析进行量化需要一个统一的表达式，该表达式能够在接受不规则或频繁间歇性血液透析（IHD）方案治疗或采用不同肾脏替代疗法的患者之间建立动力学等效性。EKRjc是等效尿素肾清除率（EKRc）的一种广义形式，代表在给定的尿素清除量下，能产生给定时间平均尿素浓度的等效持续尿素清除率。本文检验了EKRjc在这种情况下用于测量透析剂量的适用性。
使用可变容积双池尿素动力学模型在15名虚拟“患者”中模拟了420周的肾脏替代治疗（IHD和持续肾脏替代治疗）。来自8名ARF患者的额外数据用于举例说明计算过程。通过正式的尿素动力学建模以及一种简化方法计算了1260个EKRjc值，简化方法除了需要患者透析后尿素分布容积（V(T)）的初始估计值外，还需要输入观察期内患者液体状态和血尿素氮浓度的变化。
结果表明，无论IHD方案或肾脏替代疗法如何，EKRjc都能提供透析剂量的统一表达式。EKRjc与尿素稳态假设无关，并且本质上已根据患者尿素分布容积进行了标准化，以便在不同体型的患者之间进行剂量比较。如有残余肾尿素清除率，可轻松纳入计算。使用简化方法无需进行迭代尿素动力学建模即可轻松计算EKRjc。当初始V(T)估计值比真实值大或小25%时，该简化方法的准确性仍能保持。文中使用临床数据举例说明了EKRjc的计算过程。
EKRjc是对重症ARF患者透析进行量化最合适的尿素动力学表达式。
