OBJECTIVES

To describe the incidence, associated characteristics, and outcomes of the maximum severity of acute kidney injury (AKI) in a heterogeneous population of critically ill children with cardiac disease.

DESIGN

Retrospective cohort study.

SETTING

Pediatric cardiac intensive care unit (PCICU).

PARTICIPANTS

Patients admitted to the PCICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

From January 2018 to July 2020 all patients admitted to a tertiary PCICU were included. Only the first admission was considered. Neonates ≤seven days old were excluded. Of 742 patients, 53 were medical cases, 69 catheterization laboratory cases, and 620 surgical cases (with five subgroups). The median age was 2.47 years (interquartile range [IQR], 0.38-9.85 years), with a median Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery score of 2 (IQR, 1-3). Median PCICU length of stay was three days (IQR, 2-7 days), and 21 (2.8%) patients died. Any incidence of AKI occurred in 70% of patients, 26% of which were classified as mild (stage 1) and 43% as severe (stages 2 and 3). AKI was diagnosed by urine output criteria in 56%, serum creatinine in 28%, and both in 16% of patients. Severe AKI occurred in subgroups as follows: medical (38%), catheterization laboratory (45%), correction (35%), palliation (55%), transplantation (85%), mechanical assistance (70%), and redo surgery (58%). Severe AKI patients were significantly older (p = 0.004), had a higher Pediatric Index of Mortality 3 score (p = 0.0004), had a higher cumulative fluid balance (p < 0.0001), and had a longer cardiopulmonary bypass time (p < 0.0001). Early AKI (≤24 hours from admission) was the most frequent presentation, with a greater proportion of severe cases in the early group compared with the intermediate (>24 and ≤48 hours) and late (>48 hours) (p < 0.0001) groups. Presentation of late severe AKI had a higher mortality (odds ratio, 4.9; 95% confidence interval, 1.8-15; p = 0.001).

CONCLUSIONS

Severe AKI occurs in 43% of cardiac children and is diagnosed early, most often by urine output criteria. Severe AKI incidence varies significantly within subgroups of cardiac patients. Late AKI is associated with worse outcomes.