Disease severity adversely affects delivery of dialysis in acute renal failure

Intensity of renal replacement therapy and outcomes in critically ill patients with acute kidney injury: Critical appraisal of the dosing recommendations

The current care of critically ill patients with severe acute kidney injury requiring dialysis (AKI-D) is limited to supportive management in which renal replacement therapy (RRT) plays a central role. Renal replacement techniques are invasive bioincompatible procedures and are therefore associated with complications that may prove harmful to fragile patients. Inexperience with the standards and lacking or misinterpreted recommendations for the delivery of the RRT dose increases the risk of serious complications. Neither the optimal doses of intermittent or continuous RRTs nor the minimal or maximal effective doses are known. The Kidney Disease Improving Global outcomes (KDIGO) AKI guidelines for RRT dosing recommendations are inflexible, based on limited research, and may be at least partially outdated. High-intensity therapy may be associated with clinically relevant alterations in systemic and renal hemodynamics, profound electrolyte imbalances, the loss of nutrients or thermal energy, and underdosing of antimicrobial agents. However, higher doses of continuous renal replacement therapy (CRRT) may confer a survival benefit for certain subgroups of intensive care patients with severe AKI. Lower CRRT doses than the recommended adequate dosage may not lead to negative health outcomes, at least in Asian patients. Future research should evaluate the demand-capacity concept, recognizing that the delivery of the RRT dose is dynamic and should be modified in response to patient-related factors. There is a need for large-scale studies evaluating whether precision RRT dose modifications may improve patient-centered outcomes in subgroups of critically ill patients.

Solutes removal characteristics at various effluent rates during different continuous renal replacement therapy modalities

Background:

Some studies suggest the effluent as a surrogate solute removal indicator in continuous hemodialysis or hemofiltration, but the delivered clearance is frequently smaller than prescribed. This study aims at testing whether the effluent, represented by mL/kg/h, could measure solute clearance and whether increasing effluent increases clearance proportionately in continuous hemodialysis or hemofiltration.

Methods:

Patients treated with continuous renal replacement therapy for various diagnoses were included. The range of dialysate flow rate or substitution fluid flow rate was 1–5 L/h; solutes in the effluent and in the plasma entering the filter were measured, and the ratio of solutes in the effluent and in the plasma entering the filter and the clearance of blood urea nitrogen, creatinine, phosphate, and β2-microglobulin were calculated.

Results:

The ratio of solutes in the effluent and in the plasma entering the filter showed a decreasing trend with increased dialysate flow rate or substitution fluid flow rate ( p  < 0.05), but solute clearance showed an increasing trend. The increase in solute clearance was less than expected from the increased effluent ( p < 0.01), and actual delivered clearance was always below the corresponding prescribed clearance ( p < 0.001).

Conclusion:

With increasing prescribed clearance of continuous renal replacement therapy, effluent rate overestimated the delivered clearance.

Integrating Real Time Data to Improve Outcomes in Acute Kidney Injury

Critically ill patients with acute kidney injury requiring renal replacement therapy have a poor prognosis. Despite well-known factors, which contribute to outcomes, including dose delivery, patients frequently miss the target dose and volume removal. One major barrier to effective care of these patients is the traditional dissociation of dialysis device data from other clinical information systems, notably the electronic health record (EHR). This lack of integration and the resulting manual documentation leads to errors and biases in documentation and missed opportunities to intervene in a timely fashion. This review summarizes the technological advancements facilitating direct connection of dialysis devices to EHRs. This connection facilitates automated data capture of many variables - including delivered dose, ultrafiltration rate and pressure measurements - which in turn can be leveraged for data mining, quality improvement and real-time targeted therapy adjustments. These interventions hold the promise to significantly improve outcomes for this patient population.

Current practice of conventional intermittent hemodialysis for acute kidney injury

The use of conventional intermittent hemodialysis (IHD) represents a mainstay of supportive care of patients with acute kidney injury (AKI). However, a number of fundamental questions regarding the optimal management of IHD remain unanswered after more than six decades of renal replacement therapy (RRT). This review summarizes current evidence regarding the timing of initiation of intermittent hemodialysis, the comparative outcomes (mortality and recovery of renal function), the prescription of the intensity of this therapy and discontinuation of dialysis. The way conventional IHD is performed has an impact on the outcome of sick patients with AKI. The value of regular education and training of those who provide IHD cannot be emphasized enough. However, we must be realistic in our expectations that no mode of RRT per se will substantially alter the excessive mortality of critically ill-patients with AKI.

Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2)

Acute kidney injury (AKI) is a common and serious problem affecting millions and causing death and disability for many. In 2012, Kidney Disease: Improving Global Outcomes completed the first ever international multidisciplinary clinical practice guideline for AKI. The guideline is based on evidence review and appraisal, and covers AKI definition, risk assessment, evaluation, prevention, and treatment. Two topics, contrast-induced AKI and management of renal replacement therapy, deserve special attention because of the frequency in which they are encountered and the availability of evidence. Recommendations are based on systematic reviews of relevant trials. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendations Assessment, Development and Evaluation approach. Limitations of the evidence are discussed and a detailed rationale for each recommendation is provided. This review is an abridged version of the guideline and provides additional rationale and commentary for those recommendation statements that most directly impact the practice of critical care.

Can delivery dialysis dose affect survival of acute kidney injury patients?

Intensity of dialysis dose in acute kidney injury (AKI) might benefit critically ill patients. The aim of this study was to evaluate the effect of intermittent hemodialysis (IHD) dose on mortality in patients with AKI.

METHODS

Prospective observational study was performed on AKI patients treated with IHD. The delivered dialysis dose per session was calculated based on single-pool Kt/V urea. Patients were allocated in two groups according to the weekly delivered median Kt/V: higher intensity dialysis dose (HID: Kt/V higher than median) and lower intensity dialysis dose (LID: Kt/V lower than median). Thereafter, AKI patients were divided according to the presence or absence of sepsis and urine output. Clinical and lab characteristics and survival of AKI patients were compared.

RESULTS

A total of 121 AKI patients were evaluated. Forty-two patients did not present with sepsis and 45 did not present with oliguria. Mortality rate after 30 days was lower in the HID group without sepsis (14.3% × 47.6%; p = 0.045) and without oliguria (31.8% × 69.5%; p = 0.025). Survival curves also showed that the HID group had higher survival rate when compared with the LID group in non-septic and non-oliguric patients (p = 0.007 and p = 0.003, respectively).

CONCLUSION

Higher dialysis doses can be associated with better survival of less seriously ill AKI patients.

Comparison of sustained hemodiafiltration with continuous venovenous hemodiafiltration for the treatment of critically ill patients with acute kidney injury

Despite improvements in medical care, the mortality of critically ill patients with acute kidney injury (AKI) who require renal replacement therapy (RRT) remains high. We describe a new approach, sustained hemodiafiltration, to treat patients who suffered from acute kidney injury and were admitted to intensive care units (ICUs). In our study, 60 critically ill patients with AKI who required RRT were treated with either continuous venovenous hemodiafiltration (CVVHDF) or sustained hemodiafiltration (S-HDF). The former was performed by administering a postfilter replacement fluid at an effluent rate of 35 mL/kg/h, and the latter was performed by administering a postfilter replacement fluid at a dialysate-flow rate of 300-500 mL/min. The S-HDF was delivered on a daily basis. The baseline characteristics of the patients in the two treatment groups were similar. The primary study outcome--survival until discharge from the ICU or survival for 30 days, whichever was earlier--did not significantly differ between the two groups: 70% after CVVHDF and 87% after S-HDF. The hospital-survival rate after CVVHDF was 63% and that after S-HDF was 83% (P < 0.05). The number of patients who showed renal recovery at the time of discharge from the ICU and the hospital and the duration of the ICU stay significantly differed between the two treatments (P < 0.05). Although there was no significant difference between the mean number of treatments performed per patient, the mean duration of daily treatment in the S-HDF group was 6.5 +/- 1.0 h, which was significantly shorter. Although the total convective volumes--the sum of the replacement-fluid and fluid-removal volumes--did not differ significantly, the dialysate-flow rate was higher in the S-HDF group. Our results suggest that in comparison with conventional continuous RRT, including high-dose CVVHDF, more intensive renal support in the form of postdilution S-HDF will decrease the mortality and accelerate renal recovery in critically ill patients with AKI.

The dark side of high-intensity renal replacement therapy of acute kidney injury in critically ill patients

The impact of intensity or dose of renal replacement therapy (RRT) on outcome of critically ill patients has been a matter of controversy. Most definitions of an adequate dose of acute RRT are based on urea removal, while ignoring other crucial aspects of RRT adequacy in acute kidney injury (AKI). Although some clinical trials have found an improvement in survival with higher doses of intermittent hemodialysis or continuous RRT, results have not been consistent across all studies. The largest trials suggest that there is no additional survival benefit with doses of 35-45 ml/kg/h (CRRT) or daily intermittent hemodialysis. On the other hand, high-intensity treatment may cause life-threatening complications and thereby counteract the benefits of higher small-solute clearance. One important area for future investigations is the need to characterize the potential harm of high-dose RRT for AKI in critically ill patients.