Objectives To evaluate the clinical differences betweenpatients developing early acute kidney injury (EAKI) and late acute kidneyinjury (LAKI) during their stay in a PICU.

Methods Retrospective study including patients admitted to the PICU over the last 4 years. Children were excluded if they had a length of stay of less than 2 days or if they had end stage renal disease. AKI was defined according to the KDIGO criteria. The episodes of AKI that began within the first 72 h of admission were considered early AKI (EAKI), and those that appeared later were considered LAKI.

Results 1082 patients fulfilled the inclusion criteria. 415 patients (38.3%) developed AKI: EAKI 354 patients (173 had stage I AKI, 77 stage II and 104 stage III); 61 patients LAKI (33 stage I, 15 stage II and13 stage III). The severity and duration of the AKI, the need for dialysis and the incidence of pre renal AKI were not different between EAKI and LAKI groups. Patients with LAKI had more time of mechanical ventilation (156 h vs 72 h, p0.006) and a longer PICU stay (13 vs 7 days, p < 0.001). There were no differences in age or mortality between groups. LAKI was found to be more frequent in post-operative cardiac patients (41%) (p < 0.001).

Conclusions LAKI is associated with more time of MV, longer PICU stay and with the cause of admission to the PICU. However LAKI is not associated with greater severity or mortality than EAKI.