Impact of Downtime on Clinical Outcomes in Critically Ill Patients with Acute Kidney Injury Receiving Continuous Renal Replacement Therapy.

Continuous renal replacement therapy (CRRT) downtime is considered a quality indicator; however, it remains uncertain whether downtime affects outcomes. This study retrospectively investigated the impact of downtime on clinical outcomes. Patients were classified as downtime <20% or ≥20% of potential operative time over 4 days from CRRT initiation. Patients with ≥20% downtime were matched to those with <20% downtime using 1:2 propensity score matching. There were 88 patients with <20% downtime and 44 patients with ≥20% downtime. The cumulative effluent volume was lower in patients with ≥20% downtime (p < 0.001). The difference in levels of urea and creatinine widened over time (p = 0.004 and <0.001). At days 2 and 3, daily fluid balance differed (p = 0.046 and 0.031), and the levels of total carbon dioxide were lower in those with ≥20% downtime (p = 0.038 and 0.020). Based on our results, ≥20% downtime was not associated with increased 28 day mortality; however, a subgroup analysis showed the interaction between downtime and daily fluid balance (p = 0.004). In conclusion, increased downtime could impair fluid and uremic control and acidosis management. Moreover, the adverse effect of downtime on fluid control may increase mortality rate. Further studies are needed to verify the value of downtime in critically ill patients requiring CRRT.