1
|
Iman Y, Bamforth R, Ewhrudjakpor R, Komenda P, Gorbe K, Whitlock R, Bohm C, Tangri N, Collister D. The impact of dialysate flow rate on haemodialysis adequacy: a systematic review and meta-analysis. Clin Kidney J 2024; 17:sfae163. [PMID: 38979109 PMCID: PMC11229034 DOI: 10.1093/ckj/sfae163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Indexed: 07/10/2024] Open
Abstract
Background Patients with kidney failure treated with maintenance haemodialysis (HD) require appropriate small molecule clearance. Historically, a component of measuring 'dialysis adequacy' has been quantified using urea kinetic modelling that is dependent on the HD prescription. However, the impact of dialysate flow rate on urea clearance remains poorly described in vivo and its influence on other patient-important outcomes of adequacy is uncertain. Methods We searched Embase, MEDLINE and the Cochrane Library from inception until April 2022 for randomized controlled trials and observational trials comparing a higher dialysate flow rate (800 ml/min) and lower dialysate flow rate (300 ml/min) with a standard dialysis flow rate (500 ml/min) in adults (age ≥18 years) treated with maintenance HD (>90 consecutive days). We conducted a random effects meta-analysis to estimate the pooled mean difference in dialysis adequacy as measured by Kt/V or urea reduction ratio (URR). Results A total of 3118 studies were identified. Of those, nine met eligibility criteria and four were included in the meta-analysis. A higher dialysate flow rate (800 ml/min) increased single-pool Kt/V by 0.08 [95% confidence interval (CI) 0.05-0.10, P < .00001] and URR by 3.38 (95% CI 1.97-4.78, P < .00001) compared with a dialysate flow rate of 500 ml/min. Clinically relevant outcomes including symptoms, cognition, physical function and mortality were lacking and studies were generally at a moderate risk of bias due to issues with randomization sequence generation, allocation concealment and blinding. Conclusion A higher dialysate flow increased urea-based markers of dialysis adequacy. Additional high-quality research is needed to determine the clinical, economic and environmental impacts of higher dialysate flow rates.
Collapse
Affiliation(s)
- Yasmin Iman
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
| | - Ryan Bamforth
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
| | - Ruth Ewhrudjakpor
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
| | - Paul Komenda
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
- Quanta Dialysis Technologies, Alcester, UK
- University of Manitoba, Rady Faculty of Health Sciences, Department of Internal Medicine, Winnipeg, Manitoba, Canada
| | | | - Reid Whitlock
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
| | - Clara Bohm
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
- University of Manitoba, Rady Faculty of Health Sciences, Department of Internal Medicine, Winnipeg, Manitoba, Canada
| | - Navdeep Tangri
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
- University of Manitoba, Rady Faculty of Health Sciences, Department of Internal Medicine, Winnipeg, Manitoba, Canada
| | - David Collister
- Seven Oaks Hospital Chronic Disease Innovation Centre, Winnipeg, Manitoba, Canada
- University of Manitoba, Rady Faculty of Health Sciences, Department of Internal Medicine, Winnipeg, Manitoba, Canada
- University of Alberta, Faculty of Medicine & Dentistry, Department of Medicine, Edmonton, Alberta, Canada
| |
Collapse
|
3
|
Abstract
Dialyzer clearance of urea multiplied by dialysis time and normalized for urea distribution volume (Kt/Vurea or simply Kt/V) has been used as an index of dialysis adequacy since more than 30 years. This article reviews the flaws of Kt/V, starting with a lack of proof of concept in three randomized controlled hard outcome trials (RCTs), and continuing with a long list of conditions where the concept of Kt/V was shown to be flawed. This information leaves little room for any conclusion other than that Kt/V, as an indicator of dialysis adequacy, is obsolete. The dialysis patient might benefit more if, instead, the nephrology community concentrates in the future on pursuing the optimal dialysis dose that conforms with adequate quality of life and on factors that are likely to affect outcomes more than Kt/V. These include residual renal function, volume status, dialysis length, ultrafiltration rate, the number of intra-dialytic hypotensive episodes, interdialytic blood pressure, serum potassium and phosphate, serum albumin, and C reactive protein.
Collapse
Affiliation(s)
- Raymond Vanholder
- Nephrology Section, Department of Internal Medicine, University Hospital Ghent, Ghent, Belgium
| | - Wim Van Biesen
- Nephrology Section, Department of Internal Medicine, University Hospital Ghent, Ghent, Belgium
| | - Norbert Lameire
- Nephrology Section, Department of Internal Medicine, University Hospital Ghent, Ghent, Belgium
| |
Collapse
|
4
|
Jones CB, Bargman JM. Should we look beyond Kt/V urea in assessing dialysis adequacy? Semin Dial 2018; 31:420-429. [PMID: 29573025 DOI: 10.1111/sdi.12684] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Since the advent of maintenance dialysis therapy, our interpretation of what adequate dialysis really is has broadened and become more controversial. This is not only due to our changing and aging dialysis population but also to our evolving knowledge base. As nephrologists, we strive to achieve both quality and (often) quantity of life for our patients and we feel reassured when we have a quantifiable marker to show for our efforts. However, we suggest that adequate dialysis reaches far beyond the realms of attaining a particular biochemical result. Dialysis adequacy should encompass a more comprehensive assessment of patient well-being. This metric could comprise quality of life and patient-specified goals, sufficient small solute and middle molecule clearance, optimal blood pressure control, and effective bone-mineral balance, all in the context of minimizing mortality and morbidity, and a livable dialysis regimen for the patient.
Collapse
Affiliation(s)
- Clare B Jones
- Division of Nephrology, University Health Network, Toronto, Canada
| | - Joanne M Bargman
- Division of Nephrology, University Health Network, Toronto, Canada
| |
Collapse
|
5
|
Kalim S, Karumanchi SA, Thadhani RI, Berg AH. Protein carbamylation in kidney disease: pathogenesis and clinical implications. Am J Kidney Dis 2014; 64:793-803. [PMID: 25037561 PMCID: PMC4209336 DOI: 10.1053/j.ajkd.2014.04.034] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 04/30/2014] [Indexed: 12/29/2022]
Abstract
Carbamylation describes a nonenzymatic posttranslational protein modification mediated by cyanate, a dissociation product of urea. When kidney function declines and urea accumulates, the burden of carbamylation naturally increases. Free amino acids may protect proteins from carbamylation, and protein carbamylation has been shown to increase in uremic patients with amino acid deficiencies. Carbamylation reactions are capable of altering the structure and functional properties of certain proteins and have been implicated directly in the underlying mechanisms of various disease conditions. A broad range of studies has demonstrated how the irreversible binding of urea-derived cyanate to proteins in the human body causes inappropriate cellular responses leading to adverse outcomes such as accelerated atherosclerosis and inflammation. Given carbamylation's relationship to urea and the evidence that it contributes to disease pathogenesis, measurements of carbamylated proteins may serve as useful quantitative biomarkers of time-averaged urea concentrations while also offering risk assessment in patients with kidney disease. Moreover, the link between carbamylated proteins and disease pathophysiology creates an enticing therapeutic target for reducing the rate of carbamylation. This article reviews the biochemistry of the carbamylation reaction, its role in specific diseases, and the potential diagnostic and therapeutic implications of these findings based on recent advances.
Collapse
Affiliation(s)
- Sahir Kalim
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA; Harvard Medical School, Boston, MA
| | - S Ananth Karumanchi
- Harvard Medical School, Boston, MA; Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, MA; Howard Hughes Medical Institute, Boston, MA
| | - Ravi I Thadhani
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Boston, MA; Harvard Medical School, Boston, MA
| | - Anders H Berg
- Harvard Medical School, Boston, MA; Department of Pathology, Division of Clinical Chemistry, Beth Israel Deaconess Medical Center, Boston, MA.
| |
Collapse
|