ICU · equipment-physics
Renal Replacement Therapy Equipment — Comprehensive (Haemofilter Membranes, Diffusion vs Convection, the RRT Circuit and Pressures, Regional Citrate)
Also known as RRT equipment · Haemodialysis · Haemofiltration · CVVH · CVVHDF · Dialyzer membrane · Diffusion vs convection · Regional citrate anticoagulation · Sieving coefficient · Transmembrane pressure · High-flux membrane · Solute drag · Ultrafiltration · Hollow fibre dialyser
Renal replacement therapy equipment for the ICU First Part: membranes and filters, diffusion, convection and ultrafiltration, the modalities, the circuit and its pressures, filtration fraction, dose, and circuit anticoagulation with heparin or regional citrate.
Checked against its sources on 23 Oct 2026
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Target exams
Red flags
- Access pressure of -200 mmHg or more negative has been correlated with circuit failure within 12 h
- Transmembrane pressure above 300 mmHg indicates a need for potential filter replacement
- Regional citrate: a total-to-ionised calcium ratio above 2.5 indicates citrate accumulation syndrome and citrate must be stopped
- Antibiotic dosing on RRT: current vancomycin regimens reached target concentrations against susceptible pathogens in only 60% of evaluations; higher dosing may be required with high effluent flow rates or poorly susceptible pathogens
Meet the patient
A 62-year-old man in septic shock from ascending cholangitis, KDIGO stage 3 AKI, is on CVVHDF four hours after an emergency ERCP sphincterotomy. He is oozing from the cannulation site, his haemoglobin has slid from 105 to 78 g/L, his INR is 1.9, and his liver is only moderately functioning. The circuit has clotted twice in twelve hours. The nurse holds up the next set of lines and asks the only question that matters tonight: citrate, heparin, or nothing?[8][23][12]
This one patient holds the whole RRT exam — the membrane, the circuit, the pressure pattern that explains the clotting, and the anticoagulation dilemma that bleeding plus liver failure create. Answer those four and you have answered the equipment topic.[1][2]
References26ShowHide
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- [3]Palevsky PM, Zhang JH, O'Connor TZ, et al. Intensity of renal support in critically ill patients with acute kidney injury N Engl J Med, 2008.PMID 18492867
- [4]Bellomo R, Cass A, Cole L, et al. Intensity of continuous renal-replacement therapy in critically ill patients N Engl J Med, 2009.PMID 19846848
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- [8]Zarbock A, Küllmar M, Kindgen-Milles D, et al. Effect of Regional Citrate Anticoagulation vs Systemic Heparin Anticoagulation During Continuous Kidney Replacement Therapy on Dialysis Filter Life Span and Mortality Among Critically Ill Patients With Acute Kidney Injury: A Randomized Clinical Trial JAMA, 2020.PMID 33095849
- [9]Monchi M, Berghmans D, Ledoux D, et al. Citrate vs. heparin for anticoagulation in continuous venovenous hemofiltration: a prospective randomized study Intensive Care Med, 2004.PMID 14600809
- [10]Oudemans-van Straaten HM, Bosman RJ, Koopmans M, et al. Citrate anticoagulation for continuous venovenous hemofiltration Crit Care Med, 2009.PMID 19114912
- [11]Morabito S, Pistolesi V, Tritapepe L, et al. Regional citrate anticoagulation in cardiac surgery patients at high risk of bleeding: a continuous veno-venous hemofiltration protocol with a low concentration citrate solution Crit Care, 2012.PMID 22738289
- [12]Meier-Kriesche HU, Gitomer J, Finkel K, et al. Increased total to ionized calcium ratio during continuous venovenous hemodialysis with regional citrate anticoagulation Crit Care Med, 2001.PMID 11373461
- [13]Link A, Klingele M, Speer T, et al. Total-to-ionized calcium ratio predicts mortality in continuous renal replacement therapy with citrate anticoagulation in critically ill patients Crit Care, 2012.PMID 22643456
- [14]Crosswell A, Brain MJ, Roodenburg O Vascular access site influences circuit life in continuous renal replacement therapy Crit Care Resusc, 2014.PMID 24888283
- [15]Jamal JA, Udy AA, Lipman J, et al. The impact of variation in renal replacement therapy settings on piperacillin, meropenem, and vancomycin drug clearance in the critically ill: an analysis of published literature and dosing regimens Crit Care Med, 2014.PMID 24674926
- [16]Hakim RM, Wingard RL, Parker RA Effect of the dialysis membrane in the treatment of patients with acute renal failure N Engl J Med, 1994.PMID 7935703
- [17]Schneider AG, Bellomo R, Bagshaw SM, et al. Choice of renal replacement therapy modality and dialysis dependence after acute kidney injury: a systematic review and meta-analysis Intensive Care Med, 2013.PMID 23443311
- [18]Scheinkestel CD, Kar L, Marshall K, et al. Prospective randomized trial to assess caloric and protein needs of critically Ill, anuric, ventilated patients requiring continuous renal replacement therapy Nutrition, 2003.PMID 14624937
- [19]Uchino S, Bellomo R, Goldsmith D, et al. Super high flux hemofiltration: a new technique for cytokine removal Intensive Care Med, 2002.PMID 12029417
- [20]Balgobin S, Morena M, Brunot V, et al. Continuous Veno-Venous High Cut-Off Hemodialysis Compared to Continuous Veno-Venous Hemodiafiltration in Intensive Care Unit Acute Kidney Injury Patients Blood Purif, 2018.PMID 29972818
- [21]Ruiz EF, Ortiz-Soriano VM, Talbott M, et al. Development, implementation and outcomes of a quality assurance system for the provision of continuous renal replacement therapy in the intensive care unit Sci Rep, 2020.PMID 33244053
- [22]Ricci D, Panicali L, Facchini MG, Mancini E Citrate Anticoagulation during Continuous Renal Replacement Therapy Contrib Nephrol, 2017.PMID 28535516
- [23]Legrand M, Tolwani A Anticoagulation strategies in continuous renal replacement therapy Semin Dial, 2021.PMID 33684244
- [24]Tian JH, Ma B, Yang K, et al. Bicarbonate- versus lactate-buffered solutions for acute continuous haemodiafiltration or haemofiltration Cochrane Database Syst Rev, 2015.PMID 25740673
- [25]Hu C, Shui P, Zhang B, et al. How to safeguard the continuous renal replacement therapy circuit: a narrative review. Frontiers in medicine, 2024.PMID 39234046
- [26]Karkar A, Ronco C Prescription of CRRT: a pathway to optimize therapy. Annals of intensive care, 2020.PMID 32144519