McCafferty Kieran, Fan Stanley L S
Department of Renal Medicine and Transplantation, Barts and The London Hospital NHS Trust, London, United Kingdom.
Perit Dial Int. 2006 May-Jun;26(3):349-52.
Accurate measurement of ultrafiltration (UF) is important to improve the morbidity and mortality of peritoneal dialysis (PD) patients. The introduction of "flush-before-fill" PD systems has led to improved peritonitis rates. Partly to compensate for dialysate lost during flush-before-fill, extra dialysate was added to each PD bag. A 2-L PD bag now contains a mean volume of 2.225 L. That overfill volume might be erroneously measured as UF. We previously studied how this confounding factor might be affecting the diagnosis of UF failure and found that almost all units were overestimating daily UF by 900 mL. We now repeat the study to determine if the accuracy of UF estimation has improved.
We conducted a telephone survey of PD units in the UK to determine how drain bags are weighed and how UF is calculated during formal assessment of adequacy and the peritoneal equilibrium test (PET). We also retrospectively analyzed our last 100, 24-hour dialysate collections and PET results to determine the potential clinical impact of overestimating UF.
There has been an improvement since our last study, but 70% of PD units in the UK are still overestimating daily UF in patients on continuous ambulatory PD (CAPD). Half the surveyed units also inaccurately calculate UF during the PET, and 85% were reporting results of PET and 24-hour dialysate collections through the software provided by Baxter Healthcare. By including the overfill volume, 73% of patients with daily UF <750 mL would not be diagnosed as having inadequate daily UF (assuming that all were fluid overloaded and anuric). Similarly, 73% with potential UF failure during the PET (4-hour UF <100 mL) would be missed if overfill volume was misrepresented as UF.
For patients undergoing CAPD, there requires standardization on when drain bags are weighed. Awareness that calculation of UF must exclude overfill volumes has improved but remains poor. The PD Adequest software (Baxter Healthcare, Compton, UK) is widely adopted in the UK and perhaps it could draw attention of users to the potential of UF overestimation in CAPD patients.
准确测量超滤量（UF）对于改善腹膜透析（PD）患者的发病率和死亡率至关重要。“先冲洗再灌注”PD系统的引入降低了腹膜炎发生率。为部分补偿先冲洗再灌注过程中损失的透析液，每个PD袋中都额外添加了透析液。现在一个2升的PD袋平均含有2.225升液体。该过量填充体积可能会被错误地计为超滤量。我们之前研究了这个混杂因素可能如何影响超滤失败的诊断，发现几乎所有单位每日超滤量都高估了900毫升。我们现在重复这项研究以确定超滤量估计的准确性是否有所提高。
我们对英国的PD单位进行了电话调查，以确定在进行充分性正式评估和腹膜平衡试验（PET）期间如何称量引流袋以及如何计算超滤量。我们还回顾性分析了我们最近的100份24小时透析液收集情况和PET结果，以确定高估超滤量的潜在临床影响。
自我们上次研究以来情况有所改善，但英国70%的PD单位在持续非卧床腹膜透析（CAPD）患者中仍高估每日超滤量。一半的受调查单位在PET期间计算超滤量也不准确，85%通过百特医疗保健公司提供的软件报告PET和24小时透析液收集结果。如果将过量填充体积计入超滤量，73%每日超滤量<750毫升的患者不会被诊断为每日超滤量不足（假设所有患者均液体过载且无尿）。同样，如果将过量填充体积错误地计为超滤量，73%在PET期间有潜在超滤失败（4小时超滤量<1毫升）的患者会被漏诊。
对于接受CAPD的患者，需要对标称量引流袋的时间进行标准化。虽然对计算超滤量时必须排除过量填充体积的认识有所提高，但仍然很差。PD Adequest软件（百特医疗保健公司，英国康普顿）在英国被广泛采用，也许它可以提醒用户注意CAPD患者中超滤量高估的可能性。
