Acute kidney injury in critical care: experience of a conservative strategy

Abstract

Purpose: Renal replacement therapy (RRT) is a major supportive treatment of acute kidney injury (AKI) in intensive care unit (ICU), but the timing of its initiation remains open to debate.

Materials and methods: We retrospectively analyzed ICU patients who had AKI associated with at least one usual RRT criteria: serum creatinine concentration greater than 300 μmol/L, serum urea concentration greater than 25 mmol/L, serum potassium concentration greater than 6.5 mmol/L, severe metabolic acidosis (arterial blood pH<7.2), oliguria (urine output<135 mL/8 hours or <400 mL/24 hours), overload pulmonary edema. To estimate the risk of death associated with RRT adjusted for risk factors, we performed a marginal structural Cox model with inverse-probability-of-treatment-weighted estimator.

Results: Among 4173 patients admitted to the ICU, 203 patients fulfilled potential RRT criteria. Ninety-one patients (44.8%) received RRT and 112 (55.2%) did not. Non-RRT and RRT patients differed in terms of severity of illness: Simplified Acute Physiology Score II (55±17 vs 60±19, respectively; P<.05) and Sequential Organ Failure Assessment score (8 [5-10] vs 9 [7-11], respectively; P=.01). Crude analysis indicated a lower ICU mortality for non-RRT compared with RRT patients (18% vs 45%; P<.001). In the marginal structural Cox model, RRT was associated with increased mortality (P<.01).

Conclusion: A conservative approach of AKI was not associated with increased mortality.

Keywords: Acute kidney injury; Critical care; Renal replacement therapy; Treatment outcome.