Very Transient Cases of Acute Kidney Injury in the Early Postoperative Period After Cardiac Surgery: The Relevance of More Frequent Serum Creatinine Assessment and Concomitant Urinary Biochemistry Evaluation

ObjectiveTo evaluate if more frequent serum creatinine (sCr) measurements in the early postoperative period (first 48 hours) after cardiac surgery would help in early diagnosis of acute kidney injury (AKI), as well as reveal cases of AKI duration of fewer than 24 hours (vtAKI). The sequential blood and urinary biochemical profile of patients who developed vtAKI was compared with that of the patients who did not develop AKI or who developed AKI for more than 48 hours (pAKI).DesignA retrospective analysis of prospectively collected data.SettingTwo intensive care units of 2 private hospitals.ParticipantsTwenty-nine patients who underwent cardiac surgery who had 6 values of serum creatinine (sCr) measured within the first 48 hours after surgery and concomitant spot urine samples for urine biochemistry assessment.InterventionsNone.Measurements and Main ResultsEighteen patients (62%) developed Acute Kidney Injury Network (AKIN) sCr-based AKI, half of them for fewer than 24 hours. Most AKI patients had the sCr increase diagnosed 6 to 12 hours after surgery. When comparing the sequential alterations of blood and urinary parameters among patients with no AKI, vtAKI, and pAKI, the authors found that most of them were similar among groups, differing only in magnitude and duration.ConclusionsMore frequent sCr measurements in the early postoperative period, together with urine biochemistry assessment, have the potential to anticipate AKI diagnosis after cardiac surgery and reveal cases of very transient AKI usually not diagnosed in current practice. The clinical relevance of these findings must be evaluated in larger, prospective studies.