OLIGURIA AND ACUTE KIDNEY INJURY IN CRITICALLY ILL CHILDREN: IMPLICATIONS FOR DIAGNOSIS AND OUTCOME

Kaddourah A, Basu RK, Goldstein SL, Sutherland SM. Pediatr Crit Care Med. 2019;20(4):332-339.

In this post hoc analysis of the Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology study, the researchers sought to study the role of urine output (UOP) criteria in acute kidney injury (AKI) identification and evaluation. The researchers state the definition for AKI is based on changes in serum creatinine and UOP. However, the effect of UOP criteria is poorly understood. The aim of the study was to describe the epidemiology of oliguric AKI and the contribution of the UOP criteria on severe AKI ascertainment, epidemiology, and outcomes on critically ill children. The primary outcomes observed were 28-day mortality with secondary outcomes being rapid response utilization, mechanical ventilation utilization, and extracorporeal membrane oxygenation.

Critically ill children (n = 3318) who were enrolled in the Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology database were the subjects. In an effort to assess the differential impact of creatinine and UOP criteria on severe kidney injury, the researchers divided the patients into 4 cohorts: no severe AKI, severe kidney injury by creatinine criteria only, severe AKI by urine out criteria only, and severe AKI by both creatinine and UOP criteria. Of these children, severe kidney injury occurred in 496, with 343 of these children being creatinine criteria only, 90 being UOP criteria only, and 63 being both creatinine and UOP criteria.

The 28-day mortality for creatinine-criteria-only and UOP-only patients was similar (6.7% vs 7.8%, respectively) and higher than those without severe AKI (2.9%; P < .01). The creatinine and UOP criteria patients had a higher morality than creatinine-only and UOP-only patients (38.1%; P < .001). Compared with children without severe kidney injury, the relative risk of receiving dialysis significantly increased from 9.1 in creatinine criteria only to 28.2 in UOP criteria only and to 165.7 in both creatinine and UOP criteria.

The researchers found that nearly 1 in 5 critically ill children does not experience an increase in serum creatinine. However, children with a decreased UOP were at a higher risk for poorer AKI-related sequelae. They recommend the use of both creatinine and UOP for a more comprehensive assessment of AKI and identification of children who may be at a higher risk for mortality and morbidity.