Supplementary Material for: Ammonia Clearance with Different Continuous Renal Replacement Therapy Techniques in Patients with Liver Failure

<b><i>Introduction:</i></b> Continuous renal replacement therapy (CRRT) can be used to treat hyperammonaemia. However, no study has assessed the effect of different CRRT techniques on ammonia clearance. <b><i>Methods:</i></b> We compared 3 different CRRT techniques in adult patients with hyperammonaemia, liver failure, and acute kidney injury. We protocolized CRRT to progressively deliver continuous veno-venous haemofiltration (CVVH), haemodialysis (CVVHD) or haemodiafiltration (CVVHDF). Ammonia was simultaneously sampled from the patient’s arterial blood and effluent fluid for each technique. We applied accepted equations to calculate clearance. <b><i>Results:</i></b> We studied 12 patients with a median age of 47 years (interquartile range [IQR] 25–79). Acute liver failure was present in 4 (25%) and acute-on-chronic liver failure in 8 (75%). There was no significant difference in median ammonia clearance between CRRT technique; CVVH: 27 (IQR 23–32) mL/min versus CVVHD: 21 (IQR 17–28) mL/min versus CVVHDF: 20 (IQR 14–28) mL/min, <i>p</i> = 0.32. Moreover, for all techniques, ammonia clearance was significantly less than urea and creatinine clearance; urea 50 (47–54) mL/min versus creatinine 42 (IQR 38–46) mL/min versus ammonia 25 (IQR 18–29) mL/min, <i>p</i> = 0.0001. <b><i>Conclusion:</i></b> We found no significant difference in ammonia clearance according to CRRT technique and demonstrated that ammonia clearance is significantly less than urea or creatinine clearance.

<b><i>引言:</i></b> 连续性肾脏替代治疗（Continuous renal replacement therapy, CRRT）可用于治疗高氨血症，但目前尚无研究评估不同CRRT模式对氨清除的影响。<b><i>方法:</i></b> 本研究纳入合并高氨血症、肝衰竭及急性肾损伤的成年患者，比较3种不同的CRRT模式。我们按照标准化方案依次实施连续性静脉-静脉血液滤过（continuous veno-venous haemofiltration, CVVH）、连续性静脉-静脉血液透析（continuous veno-venous haemodialysis, CVVHD）及连续性静脉-静脉血液透析滤过（continuous veno-venous haemodiafiltration, CVVHDF）。对每种模式，同时采集患者动脉血及流出液中的氨标本，并采用公认公式计算氨清除率。<b><i>结果:</i></b> 本研究共纳入12例患者，中位年龄为47岁（四分位间距[IQR] 25~79）。其中4例（25%）为急性肝衰竭，8例（75%）为慢加急性肝衰竭。不同CRRT模式间的氨清除率无显著差异：CVVH组为27（IQR 23~32）mL/min，CVVHD组为21（IQR 17~28）mL/min，CVVHDF组为20（IQR 14~28）mL/min，<i>p</i> = 0.32。此外，所有CRRT模式下的氨清除率均显著低于尿素及肌酐清除率：尿素清除率为50（47~54）mL/min，肌酐清除率为42（IQR 38~46）mL/min，氨清除率为25（IQR 18~29）mL/min，<i>p</i> = 0.0001。<b><i>结论:</i></b> 本研究发现，不同CRRT模式的氨清除率无显著差异，且氨清除率显著低于尿素或肌酐清除率。