Higher Dosage of Acetaminophen Associated with Lower Risk of Acute Kidney Injury after Pediatric Cardiac Surgery

Background: Acute Kidney Injury (AKI) after pediatric cardiac surgery is manifested by injury along multiple pathways. One of these is oxidative injury related to hemolysis and subsequent deposition of hemoglobin in the kidney. Acetaminophen inhibits hemoprotein-catalyzed lipid peroxidation associated with hemolysis and in turn, may attenuate renal injury. Methods: We performed a retrospective chart review of patients undergoing pediatric cardiac surgery. A randomized controlled trial previously performed dictated a regimented, high dosage, acetaminophen. A historical cohort who received ad hoc acetaminophen prior to that study and that met the same inclusion/exclusion criteria were also analyzed, as patients from that era were likely to have less acetaminophen administered. The patients were divided into those who developed AKI and those who did not and those groups were compared by total acetaminophen dose. Important inclusion criteria included age 3 months to 4 years who underwent cardiac surgery via midline sternotomy and were extubated within three hours of admission. Patients with pre-existing or chronic kidney disease were excluded. Results: A total of 181 patients were included. Of these, 69 (38%) developed AKI. There were no significant pre- or intra-operative risk differences in characteristics between those who developed AKI and those who did not. Acetaminophen dose did significantly differ between those who developed AKI and those who did not with lower acetaminophen dose in the acute kidney injury group (30 mg/kg versus 50 mg/kg, p-value = 0.01). A multivariate analysis was performed which found that higher acetaminophen dosage and lower immediate postoperative hemoglobin were independently associated with a lower risk of AKI. Conclusion: Acute kidney injury occurs in approximately 38% after pediatric cardiac surgery. Most often this is stage 1 acute kidney injury and resolves after a day. After adjusting for other covariables, higher acetaminophen dose may be associated with lower risk of acute kidney injury. This does not prove that acetaminophen given prospectively will reduce AKI. Further studies are needed.