Timing of Kidney Replacement Therapy Initiation in Acute Kidney Injury

Alejandro Y. Meraz-Muñoz; Sean M. Bagshaw; Ron Wald


Curr Opin Nephrol Hypertens. 2021;30(3):332-338. 

In This Article

Research Implications

With the preponderance of evidence suggesting that early or preemptive initiation of KRT does not improve survival, and may confer harm, questions still remain. Although deferral of KRT in the absence of pressing indications should be the guiding principle in the management of patients with severe AKI, decision-making for the individual patient will need to be nuanced. Careful clinical assessment that integrates the individual patient's characteristics and circumstances, the trajectory of the patient's critical illness and the likelihood of kidney recovery will continue to be a vital part of deciding if and when to commence KRT.

Though not demonstrating any clear advantage with earlier KRT initiation, recently completed trials have not provided parameters for the safe duration of KRT deferral. AKIKI-2 (ClinicalTrials.gov Identifier: NCT03396757) is a recently completed RCT that will hopefully shed light on this question. This trial enrolled critically ill patients with stage 3 AKI associated with a serum urea greater than 40 mmol/l or 72 h or more of oligoanuria. Patients were allocated to a 'standard' strategy entailing KRT initiation within 12 h of randomization, or a delayed strategy of commencing KRT when serum urea exceeded 50 mmol/l or when an AKI complication supervened.[33]

Another unresolved question is the role of fluid overload as a trigger for KRT initiation. Fluid overload and its management are subjective and nuanced and were not explicitly incorporated into the protocols of the recent RCTs. Observational data have shown an association between fluid overload and adverse outcomes in AKI patients.[34–38] The threshold to consider clinically significant fluid overload in adults and the optimal method for determining fluid status is not well established.[39] Recently, point-of-care ultrasound has gained attention as a useful tool for evaluating venous congestion and intravascular volume status.[40] However, there are still limited data to inform our practice with regards of the amount of fluid accumulation necessary to trigger KRT initiation as well as the optimal ultrafiltration rate once KRT commences.[41–45]