Transcript Document
Acute renal replacement therapy – intermittent vs continuous modality
Dr.
Overview
Introduction Acute RRT: Modalities CRRT versus IHD CRRT versus SLED Conclusions
Introduction
Acute kidney injury (AKI) is Frequent complication of hospitalization Associated with substantial morbidity, mortality and health care expenditures Prevalence: 1–25% and Mortality: 20–60% associated with AKI in hospitalized patients Nephron Clin Pract 2009;112:c222–c229
Introduction
Although understanding of the epidemiology of AKI has improved, there are No proven therapies that reverse the course of established AKI Renal replacement therapy (RRT) Key component of the supportive care given to patients with severe AKI Nephron Clin Pract 2009;112:c222–c229
Introduction
RRT in AKI Approx. 4% of all critically ill patients will require RRT Among RRT-requiring patients who survive the critical phase of their illness, the majority will be free of RRT at the time of hospital discharge JAMA 2005; 294: 813–818, Crit Care 2005; 9: R700–R709.
Acute RRT: Modalities
RRT Modality Choice
Intermittent hemodialysis (IHD), Continuous renal replacement therapies (CRRT) and Sustained low-efficiency dialysis (SLED) are principal RRT modalities that are used in the acute setting Nephron Clin Pract 2009;112:c222–c229
Acute RRT: Modalities
Although institutional policies may determine the local availability of these modalities, CRRT and SLED tend to be used in patients with greater hemodynamic instability There is likely substantial intercenter variability with respect to how each of these forms of RRT is utilized and prescribed
Acute RRT: Modalities
Table: Practical comparison of acute RRT modalities Nephron Clin Pract 2009;112:c222–c229
Acute RRT: Modalities
IHD Typically administered with conventional dialysis machinery that is used in the chronic dialysis population with session length ranging from 3 to 5 h Nephron Clin Pract 2009;112:c222–c229
Acute RRT: Modalities
CRRT Is applied with an intended treatment time of 24 h and generally requires dedicated machines that operate at comparatively lower blood and dialysate pump speeds Hemodialysis (continuous venovenous hemodialysis, CVVHD), Hemofiltration (continuous venovenous hemofiltration, CVVH) or a Combination of these (continuous venovenous hemodiafiltration, CVVHDF) Nephron Clin Pract 2009;112:c222–c229
Nomenclature
Continuous renal replacement therapies
CRRT is generally better tolerated than conventional therapy, since many of the complications of intermittent hemodialysis are related to the rapid rate of solute and fluid loss CRRT involves either Dialysis (diffusion-based solute removal) or Filtration (convection-based solute and water removal) treatments that operate in a continuous mode
Continuous renal replacement therapies
Continuous venovenous hemofiltration (CVVH) Dialysis solution is not used, instead large volumes of replacement fluids are given Continuous venovenous hemodialysis (CVVHD) Dialysate is passed through at a slow rate continuously Continuous venovenous hemodiafiltration (CVVHDF) Combination; both dialysate and replacement fluids are used Slow continuous ultrafiltration (SCUF) Sustained low efficiency or extended daily dialysis (SLED)
Advantages of CRRT
In addition to better control of azotemia, fluids and hemodyanmic stability ? Enhanced clearance of inflammatory mediators, which may provide benefit in septic patients, particularly using convective modes of continuous therapy.
? Among patients with acute brain injury or fulminant hepatic failure, continuous therapy may be associated with better preservation of cerebral perfusion.
Caveats to CRRT
No evidence from randomized trials to support survival advantage Risk of complications related to anticoagulation is higher Training and equipment costs
Acute RRT: Modalities
SLED sometimes referred to as extended dialysis, is considered a ‘hybrid’ of IHD and CRRT Administered using conventional dialysis technology but typical sessions run for 8–12 h using blood and dialysis flows that are intermediate to those prescribed in IHD and CRRT Nephron Clin Pract 2009;112:c222–c229
Initial Choice of RRT for AKI
IHD Hemodynamically stable Severe hyperkalemia CRRT Hemodynamically unstable Can not tolerate fluid removal Intracranial bleed PD
CRRT versus IHD
Most trials that addressed the question of optimal RRT modality compared CRRT and IHD Table: Results of individual RCTs comparing CRRT to IHD Nephron Clin Pract 2009;112:c222–c229
CRRT versus IHD
A trial by Mehta et al. revealed higher ICU mortality in patients treated with CRRT as compared to IHD (59.5 vs. 41.5%) This finding was tempered by apparent baseline imbalances between the groups, whereby patients randomized to CRRT had a greater severity of illness Renal recovery did not differ between the groups Nephron Clin Pract 2009;112:c222–c229
CRRT versus IHD
In a larger multicenter RCT conducted in France comparing CRRT and IHD in critically ill patients with AKI, 60-day mortality was not reduced by CRRT, and there was no significant difference in the duration of RRT dependence Three additional trials have shown no survival benefit with CRRT Nephron Clin Pract 2009;112:c222–c229
CRRT versus IHD
The presumption of greater hemodynamic stability with CRRT also remains controversial Three RCTs suggested no advantage with CRRT as compared to IHD, while others demonstrated more favorable hemodynamics with CRRT Even if CRRT confers a hemodynamic benefit, It is unclear whether this translates into improvements in the patient-relevant outcomes of survival and renal recovery Nephron Clin Pract 2009;112:c222–c229
CRRT versus SLED
In addition to the absence of a survival advantage, CRRT is more costly than IHD and is associated with a number of obstacles such as Continuous patient immobilization, The requirement for anticoagulation and The need for specialized machines and premixed commercial solutions This has stimulated a search for a strategy that Incorporates the putative hemodynamic benefits of CRRT without the associated logistic and resource constraints SLED meets many of these criteria Nephron Clin Pract 2009;112:c222–c229
CRRT versus SLED
SLED Observational data from single centers suggest that SLED is a feasible way of providing RRT that is Adequate, hemodynamically well tolerated, potentially anticoagulation-free and possibly cost effective However, only two small RCTs have compared SLED and CRRT Nephron Clin Pract 2009;112:c222–c229
CRRT versus SLED
Kielstein et al. randomized 39 critically ill patients with AKI to receive Either 24 h of CVVH or 12h of SLED Using invasive monitoring, these authors found No significant differences in all measured hemodynamic parameters (mean arterial pressure, systemic vascular resistance, cardiac output) with comparable removal of creatinine and urea Am J Kidney Dis 2004; 43: 342–349.
CRRT versus SLED
A smaller study randomized 16 patients to receive three sessions with either CVVH or SLED (with an added hemofiltration component), and showed that fluid removal and hemodynamic parameters were similar in both groups Nephron Clin Pract 2009;112:c222–c229
CRRT versus SLED
Utilization of slow low-efficiency dialysis may help to optimize the need for continuous renal replacement therapy in Indian ICUs
A Majumdar, S Basu et al, AMRI Hospitals, Kolkata, The aim was to study the practice pattern of using the modern modalities of RRT, SLED and CRRT in hemodynamically unstable critically ill patients in an Indian ICU Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Indian study continued Methods A retrospective observational study of hemodynamically unstable patients with AKI who needed RRT in ICUs of a tertiary-care hospital All patients who underwent SLED and/or CRRT from September 2005 to April 2008 were taken up for analysis To maintain a mean arterial pressure (MAP) >70 mmHg, Patients who required noradrenaline >0.5 μg/kg/minute were treated with CRRT whereas those requiring ≤0.5 μg/kg/minute received SLED Depending on haemodynamic stability patients were switched from CRRT to SLED, or vice versa Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Indian study continued Results From September 2005 to April 2008, 214 haemodynamically unstable AKI patients, deemed unfit for intermittent haemodialysis, underwent SLED/CRRT (CVVH/CVVHDF) Ten patients were switched to SLED after a median 48 hours of CRRT Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Indian study continued
Results
Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Indian study continued
Results
Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Indian study continued Conclusions the need for RRT in hemodynamically unstable patients with AKI was significantly higher in the medical patients, the commonest cause of AKI being sepsis Patients who were equally sick (comparable APACHE II scores) could be effectively dialysed by SLED, as compared with CRRT Hemodynamic stability was maintained in the patients on SLED, as none needed switchover to CRRT The patients undergoing SLED were dialysed during daytime by the haemodialysis nurse, eliminating the need for a specialist nurse in the night Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Indian study continued Conclusions After a median 48 hours of CRRT, it was possible to switch to SLED, resulting in optimal utilization of resources SLED was much cheaper than CRRT In a country like India where often there are economical constraints, the judicious use of SLED will help us optimize the need for CRRT Critical Care 2009, 13(Suppl 1):P271
CRRT versus SLED
Although these preliminary data suggest that SLED may supplant CRRT as the modality of choice for hemodynamically unstable patients with AKI, further studies that utilize patient-relevant outcomes are required to define the precise role of SLED Nephron Clin Pract 2009;112:c222–c229
CRRT versus SLED
A strategy has recently been described whereby CRRT machinery was applied over a contracted treatment time of 9 h, using increased blood and effluent flow rates Termed accelerated venovenous hemofiltration, this modality retains many of the feasibility advantages of SLED, but dedicated commercial solutions were still required A retrospective case series demonstrated adequate solute removal, acceptable hemodynamic tolerability and the ability to avoid systemic anticoagulation Am JKidney Dis 2008; 51: 804–810.
PD Vs CRRT
PD
IPD, CAPD, CCPD,CFPD Common modality in pediatric patients Limitations: Effect on respiratory status - ? in using it in abdominal sepsis or abdominal surgery - Relative inefficiency in removing waste products in a catabolic patient -High incidence of associated peritonitis
PD vs CRRT
Patients with severe falciparum malaria (48 patients) and sepsis (22 patients) Assignment: 34 to hemofiltration and 36 to PD.
PD: 70 liters/ day of dialyzate was used CVVH: 25 liters of replacement fluid was used Replacement fluid was lactate based with glucose of 2g/L Dialyzate was Acetate based with glucose of 15g/L Results: PD has Lower rate of resolution of acidosis Slower rate of decline in plasma Creatinine Markedly increased risk of death
Conclusions
Despite the conceptual advantages of CRRT, multiple RCTs have shown no evidence of improved patient outcomes with this modality, as compared to conventional IHD The logistic challenges associated with CRRT and the relatively high costs of this modality may stimulate the increased use of SLED However, well-designed RCTs are still needed to better characterize the reported benefits of SLED prior to its widespread adoption
Conclusions
The current balance of evidence suggests that among hemodynamically unstable patients, CRRT need not be administered at doses higher than 20 ml/kg/h, and in more stable patients, alternate day IHD is acceptable
Conclusions
In a country like India where often there are economical constraints, the judicious use of SLED will help us optimize the need for CRRT