With CVVH , a dialysis catheter is placed in one of the main veins of the body. This catheter has two separate lines. Convection is the process during which solutes and solvent move according to the pressure gradient.
During the hemofiltration , an ultrapure replacement fluid is reinfused to the patient to keep volume homeostasis. The efficacy of convection is mainly dependent on the size of the dialyzer membranes pores. Asked by: Emogene Sodupe asked in category: General Last Updated: 7th June, What is the difference between hemofiltration and dialysis?
As in dialysis , in hemofiltration one achieves movement of solutes across a semi-permeable membrane. With hemofiltration , dialysate is not used. Instead, a positive hydrostatic pressure drives water and solutes across the filter membrane from the blood compartment to the filtrate compartment, from which it is drained.
What is first use syndrome? First-use syndrome is a rare but severe anaphylactic reaction to the artificial kidney. Its symptoms include sneezing, wheezing, shortness of breath, back pain, chest pain, or sudden death.
It can be caused by residual sterilant in the artificial kidney or the material of the membrane itself. What does Cvvhdf stand for? What is intestinal dialysis? Intestinal dialysis has been described as the transfer of toxic substances from the blood system of the intestines to the decaying waste matter passing through the intestines and out of the body. In the body, equilibrium of uremic toxins normally exists between the blood and the intestinal lumen. What is continuous arteriovenous hemofiltration?
In CAVH electrolytes and other small and medium sized solutes are removed from the patient by ultrafiltration. More likely, future studies will have to address the question of whether there are specific subgroups of patients who might benefit from convective therapies for example, myoglobinuric or septic AKI patients in whom the enhanced removal of myoglobin or cytokines by hemofiltration might help to improve clinical course and renal recovery.
Moreover, the question of RRT 'dose' is inextricably linked with the choice of modality. This, together with a potentially reduced filter life, may lead to increased costs of convective therapies in comparison with continuous hemodialysis.
In clinical practice, the intensivist will have to balance the desired intensity of treatment, in particular with regard to the removal of larger molecules, against clotting risk, filter life, and costs. Inevitably, local experience and circumstances will also influence the choice of modality. As the current UK Renal Association guidelines [ 3 ] put it, 'choice of RRT modality should be guided by the individual patient's clinical status, medical and nursing expertise, and availability of modality'.
See related research by Friedrich et al. National Center for Biotechnology Information , U. Journal List Crit Care v. Crit Care. Published online Aug Author information Copyright and License information Disclaimer. Corresponding author.
Abstract The optimal choice of modality for acute renal replacement therapy is unclear at present. Competing interests The author declares that they have no competing interests.
The trial with the shortest measurement period 30 minutes provided a minute equilibration period after crossover prior to data collection [ 33 ]. For one other trial [ 37 ], we included data collected over 12 hours but not starting until 12 hours after crossover. Most crossover trials reported using paired analyses [ 33 — 37 , 39 ], but none provided individual patient data or mean within-patient difference data.
Therefore, we were restricted to using group-specific means to perform meta-analyses, as discussed in the Methods. The three parallel group trials that compared similar doses of hemofiltration to hemodialysis were included in the primary analysis and reported either ICU [ 24 , 25 ] or hospital [ 30 ] mortality.
Five additional parallel-group trials comparing similar [ 23 , 27 , 29 ] or different [ 21 , 26 ] doses of hemodiafiltration to either hemodialysis or hemofiltration reported mortality data and were included in the sensitivity analysis. They reported hospital [ 21 , 23 ], day [ 27 , 29 ], or day [ 26 ] mortality. We did not identify differences in pooled mortality in the primary RR 0. Visual inspection of the funnel plot for the sensitivity analysis did not suggest publication bias.
Effect of hemofiltration vs. The pooled risk ratio was calculated using a random-effects model. Weight refers to the contribution of each study to the overall estimate of treatment effect. Abbreviations: CI, confidence interval; IV, inverse variance. Dialysis dependence in survivors was not different between groups primary analysis: RR 1. One trial reported lower SOFA scores in the hemofiltration group primarily between four and seven days, driven primarily by the cardiovascular component reflecting lower vasopressor requirements ; however, this decrease was not statistically significant [ 30 ].
Another trial reported no difference in norepinephrine doses or changes in the multi-organ dysfunction score MODS [ 66 ] or APACHE II score between continuous hemofiltration and hemodialysis groups over the first 72 hours [ 24 ].
One parallel-group trial, comparing intermittent hemodiafiltration to hemodialysis, reported similar improvements in MODS between groups over 10 days [ 23 ], and another comparing sustained low efficiency dialysis to diafiltration reported similar improvements in blood pressure between groups over three days [ 29 ].
Pooled data from two small crossover trials using similar dose CVVH vs. CVVHD [ 34 , 38 ] suggest that hemofiltration may shorten the time to filter failure, although only the RoM result achieved statistical significance MD Incorporating the results of one parallel-group trial using similar dose CVVH vs.
Recognizing that higher dose may also affect filter life, two other trials comparing non-equivalent doses in the two treatment arms demonstrated shorter time to filter clotting in the higher dose group. Including the data from trials with non-equivalent doses in the two treatment arms in the pooled analysis resulted in a similar shortened time to filter failure in the hemofiltration group MD The pooled mean difference was calculated using a random-effects model.
Few molecules were examined in more than one study, and analyses included few patients. In general, small molecule clearance for example, urea, phosphate and creatinine was similar between hemofiltration and hemodialysis, whereas hemofiltration achieved higher clearance of larger molecules up to around 20 kiloDaltons kDa.
Pooled data from two studies [ 24 , 34 ] showed similar clearance of interleukin IL -6 between modes, but statistical heterogeneity was high. Single studies also found that hemofiltration delivered significantly higher clearances of protein and albumin using a high 60 kDa cut-off filter [ 24 ], and almost all amino acids in one study examining pediatric patients receiving amino acid supplementation [ 36 ]. The impact of clearance mode on serum concentrations of various solutes of interest was reported even less frequently.
A second crossover trial [ 35 ] found no differences in concentrations of mediators of endothelial activation. Finally, the crossover trial of pediatric patients receiving amino acid supplementation [ 36 ] reported lower serum concentrations of amino acids in association with higher clearances in the hemofiltration group. This systematic review and meta-analysis highlights the paucity of data from randomized controlled trials comparing hemofiltration to hemodialysis in the treatment of AKI.
Considering clinical outcomes of hemofiltration in parallel-group RCTs, there was no indication of improved mortality or organ dysfunction, although confidence intervals were wide. Our meta-analysis suggests that hemofiltration shortens filter life by about five to six hours or one-third of total mean filter time.
Based primarily on crossover RCTs, we found that hemofiltration increases the clearance of medium to larger molecules compared to hemodialysis. Almost no studies determined whether the enhanced middle-molecule clearance attributed to hemofiltration actually led to lower serum concentrations. The trials reporting on filter failure rates used primarily pre-filter addition of replacement fluid.
This hypothesis merits further evaluation in a formal cost analysis. Comparing the published practice survey data in different countries and regions [ 10 — 15 ] summarized in Figure 4 , it appears that physicians tend to use a mode with at least some hemofiltration that is, either CVVH or CVVHDF , perhaps anticipating additional benefit associated with hemofiltration.
However, the small number of trials, randomized patients and events does not support this belief. A well-designed and adequately powered trial would be necessary to establish the superiority of hemofiltration. Strengths of our review include methods to minimize bias, such as a comprehensive literature search, duplicate data abstraction, consideration of important clinical outcomes, and inclusion of additional methodological or clinical information from authors.
The primary limitation is the small number and size of RCTs comparing pure hemofiltration to pure hemodialysis at similar doses. Sensitivity analyses, including trials whose arms also varied with respect to dose, gave similar results, as expected given recent large trials [ 4 , 5 ] and meta-analyses [ 6 , 7 ] that found similar outcomes with different RRT doses.
In addition, trials varied in the modality of RRT used, timing of initiation, and types of filters and blood flows, although recent meta-analyses have not found differential outcomes based on these factors [ 70 — 73 ].
We did not consider comparisons of blood clearance modes with peritoneal dialysis [ 74 , 75 ], which is used in some areas of the world to treat acute kidney failure. Finally, heterogeneity may have been underestimated because these tests are underpowered when there are few trials. Although hemofiltration is of particular interest in patients with sepsis, in whom pro-inflammatory mediators are increased, there was insufficient data to conduct a subgroup analysis in these patients.
In addition, we did not examine the role of hemofiltration vs hemodialysis in patients with sepsis who have not yet developed AKI [ 40 ] or the role of hemofiltration compared to no RRT [ 76 — 79 ]. Pooled data from a few randomized trials suggest that hemofiltration increases the clearance of medium to larger molecules without improving clinical outcomes, though confidence intervals are wide.
Hemofiltration may also reduce filter life. This latter finding, together with the increased replacement fluid requirements to achieve equivalent small-molecule clearance when pre-filter replacement is used, suggests that hemofiltration may be more expensive than hemodialysis. Our findings support the need for additional pilot data [ 80 ] to evaluate the impact of hemofiltration vs.
Few randomized controlled trials have compared hemofiltration vs hemodialysis for the treatment of acute kidney injury. Pooling the results from these trials does not suggest beneficial clinical outcomes of hemofiltration vs hemodialysis, but confidence intervals are wide. Compared to hemodialysis, hemofiltration may increase clearance of medium to larger molecules, but may also shorten the time to filter failure.
Additional pilot trials are needed to evaluate the impact of hemofiltration vs. Intensive Care Med. PubMed Article Google Scholar. N Engl J Med. Article Google Scholar. N Eng J Med. Crit Care Med. PubMed Google Scholar.
Clin J Am Soc Nephrol. Am J Kidney Dis. Artif Organs. The beginning and ending supportive therapy for the kidney B. Renal Study Investigators: Renal replacement therapy for acute kidney injury in Australian and New Zealand intensive care units: a practice survey.
Crit Care Resusc. Google Scholar. Pediatr Nephrol. Inten Care Med. Friedrich JO, Adhikari NK, Beyene J: The ratio of means method as an alternative to mean differences for analyzing continuous outcome variables in meta-analysis: a simulation study. Stat Med. Int J Epidemiol. 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.
Alamartine E, de Filippis JP, Toulon J, Berthoux F: On-line continuous venovenous hemodiafiltration: a technique for the control of ultrafiltration and convection during continuous renal replacement therapy. Ren Fail. Pettila V, Tiula E: Intermittent hemodiafiltration in acute renal failure in critically ill patients. Clin Nephrol. Daud KM, Leong GB, Visvanathan R: Acute dialytic support for the critically ill: continuous venovenous haemodialysis versus continuous venovenous haemofiltration.
Int Med J. CAS Google Scholar.
0コメント