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| Year : 2008 | Volume
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| Issue : 4 | Page : 529-536 |
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| Renal Replacement Therapy in Acute Kidney Injury: Which Method to Use in the Intensive Care Unit? |
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Andrew Davenport
UCL Center for Nephrology, Royal Free and University College Medical School, London, United Kingdom
Click here for correspondence address and email
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 Abstract | | |
Over the last three decades the treatment options for patients with acute kidney injury (AKI) requiring renal replacement therapy (RRT) have expanded from basic acute peritoneal dialysis and intermittent hemodialysis (IHD), to now include a variety of continuous modalities (CRRT), ranging from hemofiltration, dialysis and/or hemodiafiltration, and a variety of hybrid therapies, variously described as extended daily dialysis and/or hemodiafiltration, with the possibility of additional adjunct therapies encompassing plasma separation and adsorption techniques. Current evidence does not support that one modality is superior to any other in terms of patients' survival in the intensive care unit, or at discharge. There have been two prospective audits, which have reported improved renal recovery in the survivors who were treated by CRRT rather than IHD, but this has not been confirmed in randomized controlled trials. Thus the choice of RRT modality should be guided by the individual patients' clinical status, the medical and nursing expertise in the local intensive care unit, and the availability of RRT modality. Keywords: Acute, Renal, Failure, Intensive, Care, Units, Replacement, Therapy, Hemodialysis, Hemofiltration, Hemodiafiltration
How to cite this article:
Davenport A. Renal Replacement Therapy in Acute Kidney Injury: Which Method to Use in the Intensive Care Unit?. Saudi J Kidney Dis Transpl 2008;19:529-36 |
How to cite this URL:
Davenport A. Renal Replacement Therapy in Acute Kidney Injury: Which Method to Use in the Intensive Care Unit?. Saudi J Kidney Dis Transpl [serial online] 2008 [cited 2022 Jul 1];19:529-36. Available from: https://www.sjkdt.org/text.asp?2008/19/4/529/41300 |
| Introduction | |  |
In many developed countries, continuous therapies have become the predominant mode of delivery of RRT in the ICU setting, and the majority of centers offer continuous venovenous hemofiltration (CVVH) or continuous veno-venous hemodiafiltration (CVVHDF). [1] Although, clinical practices vary from country to country, a recent multi-national survey reported that 80% of patients who need RRT were treated with continuous therapies, 16.9% with intermittent therapies, and 3.2% with either peritoneal dialysis or slow continuous ultrafiltration. [2]
| Continuous renal replacement therapy | | |
Continuous renal replacement therapies (CRRT) have blossomed since the original description by Kramer of a simple arteriovenous ultrafiltration device thirty years ago. [3] The clearances achieved with original spontaneous arteriovenous hemofiltration (CAVH) circuits were often around 16 ml/min, so additional intermittent hemodialysis was often required. To improve clearances, counter-current dialysate flow was added (CAVHD), [4],[5] followed by pumps so that circuits only required a venous blood supply (continuous veno-venous hemofiltration or continuous veno-venous hemodialysis and/or continuous veno-venous hemodiafiltration). [6] Over time, the amount of renal replacement treatment delivered to patients has increased from 20-35 ml/kg/h. [7] Subsequently, there has been an ongoing debate as to the amount of clearance required, resulting in what is termed "low volume" (20-40 ml/kg/h) and high volume therapies (70-100 ml/kg/h, usually in pulses of 6-8 hours). [8] There is currently an ongoing trial of two doses of veno-venous hemofiltation in ICU patients with acute kidney injury to try and determine whether increasing the dose of renal replacement therapy improves patients' survival.
Although there are fundamental differences between CRRT modes in terms of the amount of diffusive (dialysis) and convective (filtration) clearances [Table 1], there have been no studies that demonstrate a difference between these two basic factors in terms of patients' survival and/or renal recovery, even with greater middle molecule clearances with convective mode.
Whereas for intermittent hemodialysis and/ or hemodiafiltration dialysates and re-infusion fluids are standard with minor differences in electrolyte composition, the CRRT dialysates and re-infusion fluids differ not only in electrolyte composition, but also lactate/bicarbonate and chloride content. CRRT fluids that have a high chloride and low lactate content can lead to hyperchloremic acidosis; conversely, CRRT fluids with a lower chloride content and higher lactate can similarly result in a hypochloremic alkalosis. [9] Although bicarbonate based fluids have been shown to more effectively correct metabolic acidosis and improve cardiovascular stability compared to those containing lactate, [10] the choice of buffer base has not been proven to affect patient survival. Specially designed dialysates and/or replacement fluids are required for CRRT systems using trisodium citrate anticoagulation, due to the potential citrate and sodium overload. [11]
Not all ICUs have access to nephrology input and dialysis trained nurses, so CRRT allows the staff in these units to initiate treatment of patients with acute kidney injury (AKI). Although probably less training is required to operate CRRT than hemodialysis machines, more nurse time is spent operating the machine [Table 2], and as for all machines, operator competency is required. [12] One of the problems with the recent series of CRRT machines has been the ability of the operator to over-ride alarms. This may potentially result in fluid imbalances between the prescribed rate of fluid loss and that achieved in clinical practice. CRRT is more costly than intermittent and hybrid therapies, as both the machines and consumables (blood lines, dialyzers, and/or hemofilters) are more expensive. However, the main cost is the sterile substitution fluid and/or dialysate, particularly when high volume therapies are performed. Some centers have started to produce on-line ultrapure replacement solutions/dialysates to reduce these costs. [13]
CRRT is only a successful therapy when applied continuously, otherwise patients may not receive adequate solute control. [14] Indeed, one retrospective review found that only 68% of patients received their prescribed dose of CRRT. [15] Circuit clotting and down time is a much greater problem with CRRT than intermittent and hybrid therapies, particularly in compromised ICU patients due to activation of mononuclear cells and platelets. [16]
| Intermittent therapies | | |
In the early 1980s, intermittent hemodialysis (IHD) was practiced in the ICU similarly to that of treating chronic kidney failure patients. Patients were often dialyzed thrice weekly, using bio-incompatible low flux cellulosic dialyzers, low sodium, acetate based dialysate at body temperature and with machines that did not have accurate volume regulation. However, performance of the HD machines improved with the introduction of new important features such as volume control, blood volume monitoring, and biofeedback control along with high synthetic flux bio-compatible membranes and bicarbonate dialysate. In addition, the importance of daily or at least alternate day extended treatments along with higher sodium and lower dialysate temperatures is now recognized. [17],[18] Such "bundle" effect has been demonstrated to markedly impact on reducing IHD associated hypotension. [19] In a recent prospective randomized study, many ICU patients were successfully treated with IHD, and had a similar outcome to those treated by CRRT. [18] Remarkably, the number of patients transferred from IHD to CRRT due to cardiovascular instability was less than those transferring from CRRT to IHD.
Intermittent hemofiltration (IHF), which was introduced in the 1980s for chronic kidney failure patients and used in ICUs, has mainly been superseded by intermittent hemodiafiltration (IHDF). As with CRRT, the main cost was the sterile replacement fluids. IHDF requires ultrapure water to reduce costs. Many ICUs have no access to water treatment plant in the chronic hemodialysis unit. However with the addition of simple particle filters, in combination with carbon filters and portable reverse osmosis machines, some units can provide dialysate water of ultrapure quality, especially when using dialysis machines fitted with additional ultrafilters.
| Hybrid therapies | | |
Hybrid therapies encompass a group of treatments, which are essentially based on extending the duration and slowing down the rate of diffusion of IHD. Most regimens use standard IHD machines with slower blood and dialysate flow rates [Table 3]. In addition, there is a batch IHD machine (Genius®, Fresenius Bad Homberg, Germany) in which the blood and dialysate flows are linked by a single pump, so that the flow rates are of similar magnitude. Dialysis with this machine can be extended for more than 12 hours by slowing flow rates down to 100 ml/min, although 150-200 ml/ min is more common in clinical practice.
Depending on the design, hybrid therapies can provide diffusive clearances of small solutes such as urea around 36 ml/kg/h, [20] and greater solute clearances of vitamin B12 or α 2-microglobulin close to 50-66% of that with CRRT. Furthermore, hybrid therapies can also be set up to provide hemodiafiltration that achieves large solute clearances comparable to those with CRRT.
Whereas circuit thrombosis has been reported in 20-25% of hybrid therapies using standard hemodialysis machines, clotting is much less frequent with the batch dialysate therapies, such as the Genius®. [21] This may be due to the difference in blood pump technology between the systems, with much greater leukocyte and platelet activation with the standard occlusive roller pump.
| Peritoneal Dialysis | | |
A recent worldwide survey disclosed that the use of peritoneal dialysis (PD) in adult AKI is on the decline. [2] However, acute PD is still successfully practiced in pediatric AKI, particularly post cardiac surgery, and in patients with single organ failure. PD machines are useful but not obligatory. Clearances achieved in pediatric AKI are comparable to those targeted for end-stage kidney disease. [22]
However, there have been debates as to whether PD can provide adequate clearances for treating adult AKI. One study from Brazil, reported an average urea clearance of 17.3 ± 5 ml/min, comparable to those of the non-pumped forms of arteriovenous hemofiltration and/or dialysis, by using 2 liter-fill volumes, 65-80 minutes dwell times, and glucose concentrations in excess of 2.0%. [23] However, studies that used smaller dwell volumes, and shorter dwell times demonstrated compromised clearances. [24],[25] Some authors have therefore suggested that PD could not control toxins in patients with hypercatabolic AKI, which resulted in the development of novel PD techniques such as continuous flow through PD with recycling of the peritoneal dialysate effluent. [26]
However, the number of patients suitable for PD may be limited by surgical procedures and complications that include mechanical leaks and peritonitis.
| Comparison of RRT modalities | | |
In hemodynamically unstable critically ill patients, prospective randomized clinical trials have failed to confirm the hypothesis that CRRT is superior to IHD. In many of the earlier trials, there was a bias for the more critically ill patients to receive CRRT rather than IHD. In the last 6 years however, five randomized prospective controlled trials comparing, CRRT and IHD have been published. [18],[27],[28],[29],[30] None of these trials demonstrated any difference in mortality attributable to the selected RRT modality. Although some did observe greater hemodynamic stability during CVVHD compared to IHD, [28] and similarly more effective fluid removal during CVVHD compared to IHD. However, the most recent of these studies, the Hemodiafe study, reported no significant differences in cardiovascular stability between the CRRT and IHD groups, [18] but this was the first study to deliberately apply cooled dialysate in combination with a very high dialysate sodium during IHD, and delivered the highest Kt/V dose to the IHD group, in comparison to other earlier studies. [17] Similarly meta-analyses have failed to show any significant effect of RRT modality on patient outcome. [31],[32]
Moreover, there are special circumstances such as cerebral edema and increased intracranial pressure where low volume CRRT benefited patients than high volume CVVH or IHD. [33],[34] Typically these patients have been excluded from the randomized controlled trials.
Many ICU patients experience hemodynamic instability that can be aggravated by intra-dialytic hypotension during IHD. This proposed that CRRT may be associated with more probable recovery of renal function than IHD. [35] Two prospective clinical audits reported increased renal recovery in the survivors treated by CRRT compared to IHD, [36],[37] but this has not been confirmed in randomized prospective controlled trials. [18]
Studies comparing other forms of RRT have been limited. No studies have directly compared "hybrid" treatments to either IHD or CRRT, although "hybrid" therapies have been shown to provide similar hemodynamic stability and solute control when compared to CRRT. [21]
In summary, analysis of the currently published studies does not allow evidencebased guidelines for the selection of RRT modality for the treatment of AKI. Hopefully, the recently completed Veterans study in the USA, currently the largest randomized prospective study designed to investigate the effect of treatment modality in AKI (CRRT vs. hybrid vs. IHD), [38] will provide useful information in determining the optimal treatment modality for AKI. Therefore, until this trial is concluded, the selected modality should be guided by the individual patient's clinical status, medical and nursing expertise, and the availability of RRT modality.
| References | | |
| 1. | Wright SE, Bodenham A, Short AT, Turney JH. The provision and practice of renal replacement therapy on adult intensive care units in the United Kingdom. Anaesthesia 2003;58(11):1063-9.  |
| 2. | Uchino S, Kellum JA, Bellomo R, et al. Acute renal failure in critically ill patients: a multinational, multicenter study. JAMA 2005;294(7):813-8. |
| 3. | Kramer P, Wigger W, Rieger J, Matthaei D, Scheler F. Arteriovenous haemofiltration: a new and simple method for treatment of over-hydrated patients resistant to diuretics. Klin Wschr 1977;55(22):1121-2. |
| 4. | Sigler MH, Teehan BP. Solute transport in continuous haemodialysis: a new treatment for acute renal failure. Kidney Int 1987;32 (4):562-71. |
| 5. | Davenport A, Will EJ, Davidson AM. Effect of the direction of dialysate flow on the efficiency of continuous arteriovenous haemodialysis. Blood Purif 1990;8(6):329-36. |
| 6. | Gibney RT, Kimmel PL, Lazarus M. The Acute Dialysis Quality Initiative-part I: Definitions and reporting of CRRT techniques. Adv Ren Replace Ther 2002;9(4): 252-4. |
| 7. | Ronco C, Bellomo R, Homel P, et al. Effects of different doses in continuous veno-venous haemofiltration on outcomes of acute renal failure: a prospective randomized trial. Lancet 2000;356(9223):26-30. |
| 8. | Honore PM, Jamez J, Wauthier M, et al. Prospective evaluation of short-term, highvolume isovolemic hemofiltration on the hemodynamic course and outcome in patients with intractable circulatory failure resulting from septic shock. Crit Care Med 2000;28(11):3581-7. |
| 9. | Davenport A. Dialysate and substitution fluids for patients treated by continuous forms of renal replacement therapy. Contrib Nephrol 2001;132:313-22. [PUBMED] |
| 10. | McLean AG, Davenport A, Cox D, Sweny P. Effects of lactate-buffered and lactatefree dialysate in CAVHD patients with and without liver dysfunction. Kidney Int 2000; 58(4):1765-72. |
| 11. | Davenport A. Replacement and dialysate fluids for patients with acute renal failure treated by continuous veno-venous haemofiltration and/or haemodiafiltration. Contrib Nephrol 2004;144:317-28. [PUBMED] |
| 12. | Gibney N, Cerda J, Davenport A, et al. Volume management by renal replacement therapy in acute kidney injury. Acute Dialysis Quality Initiative. Int J Artif Organs 2008;31(2):145-55. |
| 13. | Teo BW, Demirjian S, Meyer KH, Wright E, Paganini EP. Machine-generated bicarbonate dialysate for continuous therapy: a prospective, observational cohort study. Nephrol Dial Transplant 2007;22(8):2304-15. |
| 14. | Davenport A, Mehta S. The Acute Dialysis Quality Initiative-part VI: Access and anticoagulation in CRRT. Adv Ren Replace Ther 2002;9(4):273-81. |
| 15. | Uchino S, Fealy N, Baldwin I, Morimatsu H, Bellomo R. Continuous is not continuous: The incidence and impact of circuit 'down-time' on uraemic control during continuous veno-venous haemofiltration. Intensive Care Med 2003;29(4):575-8. |
| 16. | Davenport A. The coagulation system in the critically ill patient with acute renal failure and the effect of an extracorporeal circuit. Am J Kid Dis 1997;30(5):S20-7. |
| 17. | Schiffl H, Lang SM, Fischer R. Daily dialysis and the outcomes of acute renal failure. N Engl J Med 2002;346(5):305-10 |
| 18. | Vinsonneau C, Camus C, Combes A, et al. Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multipleorgan dysfunction syndrome: a multicentre randomised trial. Lancet 2006;368(9533): 379-85. |
| 19. | Schortgen F, Soubrier N, Delclaux C, et al. Hemodynamic tolerance of intermittent hemodialysis in critically ill patients. Am J Respir Crit Care Med 2000;162(1):197-202. |
| 20. | Marshall MR, Tianmin M, Galler D, Rankin AP, Williams AB. Sustained lowefficiency daily diafiltration (SLEDD-f) for critically ill patients requiring renal replacement therapy: towards an adequate therapy. Nephrol Dial Transplant 2004;19 (4):877-84. |
| 21. | Fliser D, Kielstein JT. A single-pass batch dialysis system: An ideal dialysis method for the patient in intensive care with acute renal failure. Curr Opin Crit Care 2004; 10(6):483-8. |
| 22. | McNeice KL, Ellis EE, Drummond-Webb JJ, Fontenot EE, O'Grady CM, Blaszak RT. Adequacy of peritoneal dialysis in patients following cardiopulmonary bypass surgery. Pediatr Nephrol 2005;20(7):972-6. |
| 23. | Gabriel DP, Nascimento GV, Caramori JT, Martim LC, Barretti P, Balbi AL. High volume peritoneal dialysis for acute renal failure. Perit Dial Int 2007;27(3):277-82. |
| 24. | Phu NH, Hien TT, Mai NT, et al. Hemofiltration and peritoneal dialysis in infection-associated acute renal failure in Vietnam. N Engl J Med 2002;347(12):895-902. |
| 25. | Chitalia VC, Almeida AF, Rai H, et al. Is peritoneal dialysis adequate for hypercatabolic acute renal failure in developing countries? Kidney Int 2002;61(2):747-57. |
| 26. | Ronco C, Amerling R. Continuous flow peritoneal dialysis: current state-of-the-art and obstacles to further development. Contrib Nephrol 2006;150:310-20. [PUBMED] [FULLTEXT] |
| 27. | Augustine JJ, Sandy D, Seifert TH, Paganini EP. A randomized controlled trial comparing intermittent with continuous dialysis in patients with ARF. Am J Kid Dis 2004;44(6):1000-7. |
| 28. | John S, Griesbach D, Baumgartel M, Weihprecht H, Schmieder RE, Geiger H. Effects of continuous haemofiltration VS intermittent haemodialysis on haemodynamics and splanchnic regional perfusion in septic shock patients: a prospective randomized clinical trial. Nephrol Dial Transplant 2001;16(2):320-7. |
| 29. | Mehta RL, McDonald B, Gabbai F, et al. A randomized clinical trial of continuous versus intermittent dialysis for acute renal failure. Kidney Int 2001;60(3):1154-63 |
| 30. | Uehlinger DE, Jakob SM, Ferrari P, et al. Comparison of continuous and intermittent renal replacement therapy for acute renal failure. Nephrol Dial Transplant 2005;20 (8):1630-7. |
| 31. | Kellum JA, Angus DC, Johnson JP, et al. Continuous versus intermittent renal replacement therapy: a meta-analysis. Intensive Care Med 2002;28(1):29-37. |
| 32. | Tonelli M, Manns B, Feller-Kopman D. Acute renal failure in the intensive care unit: a systematic review of the impact of dialytic modality on mortality and renal recovery. Am J Kidney Dis 2002;40(5): 875-85. |
| 33. | Davenport A, Will EJ, Davison AM. Early changes in intracranial pressure during hemofiltration treatment in patients with grade 4 hepatic encephalopathy and acute oliguric renal failure. Nephrol Dial Transplant 1990;5(3):192-8. |
| 34. | Davenport A, Will EJ, Davidson AM. Improved cardiovascular stability during continuous modes of renal replacement therapy in critically ill patients with acute hepatic and renal failure. Crit Care Med 1993;21(3):328-38. |
| 35. | Palevsky PM, Baldwin I, Davenport A, Goldstein S, Paganini E. Renal replacement therapy and the kidney: Minimizing the impact of renal replacement therapy on recovery of acute renal failure. Curr Opin Crit Care 2005;11(6):548-54. |
| 36. | Uchino S, Bellomo R, Morimatsu H, et al. Continuous renal replacement therapy: a worldwide practice survey. The Beginning and Ending Supportive Therapy for the Kidney (B.E.S.T. Kidney) Investigators. Intensive Care Med 2007;33(9):1563-70. |
| 37. | Bell M, SWING, Granath F, Schon S, Ekbom A, Martling CR. Continuous renal replacement therapy is associated with less chronic renal failure than intermittent haemodialysis after acute renal failure. Intensive Care Med 2007;33(5):773-80. |
| 38. | Available from: http://www.atnstudy.org/http://clinicaltrial s.gov/show/NCT0076219. http://s.gov/show/NCT0076219. |
Correspondence Address:
Andrew Davenport
UCL Center for Nephrology, Royal Free & University College Medical School, Hampstead Campus, Rowland Hill Street, London NW3 2PF
United Kingdom
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 18580008 
[Table 1], [Table 2], [Table 3] |
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