Pediatric Cardiology

Association of Preoperative Diuretic Use With Early Acute Kidney Injury in Infants With Biventricular Hearts Following Cardiac Surgery. Rathgeber SL, Chakrabarti A, Kapravelou E, Hemphill N, Voss C, Mammen C, Skippen P, Harris KC.J Am Heart Assoc. 2021 Oct 19;10(20):e020519. doi: 10.1161/JAHA.120.020519. Epub 2021 Oct 8. PMID: 34622667   Take Home Points: Preoperative diuretic use does not increase the risk of Cardiac Surgery associated acute kidney injury (CS-AKI) in infants early after surgery. A diagnosis of tetralogy of Fallot was the only risk factor for CS-AKI identified using multivariate analysis in the author’s cohort. Furthermore, a diagnosis of tetralogy of Fallot and longer cardiopulmonary bypass time are risk factors for moderate to severe CS-AKI.   Commentary from Dr. Manoj Gupta (New York City, NY, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch.   Introduction Diagnosis of cardiac surgery associated acute kidney injury (CS-AKI) is recognized as a significant complication in both pediatric and adult populations that is associated with increased morbidity and mortality. Diuretic therapy is a mainstay in pre-operative medical management of congenital heart disease to control the symptoms of congestive heart failure.   Methods: AKI was defined as a rise in serum creatinine (SCr) >50% from preoperative baseline or < 0.5 ml/kg per hour of urine output for any 6-hour period postoperatively as defined by the Kidney Disease Improving Global Outcomes Guidelines (KDIGO) classification, which is recommended for use in pediatric populations. Urine output was measured over 6-hour intervals for the first 18 hours postoperatively in the cardiac intensive care unit while an indwelling catheter was in place. Patients who met the KDIGO criteria to have CS-AKI based on either the SCr or urine output criteria were further classified to have either mild (stage 1), moderate (stage 2), or severe (stage 3) AKI according to the KDIGO classification system. Preoperative diuretic use in this study refers to any patient taking the loop diuretic furosemide as this was the preferential mode for management of infants with CHF at our center. The dose range of furosemide was between 1 and 3 mg/ kg per day divided 1 to 3 times per day and was administered orally in all cases. Most patients were concurrently taking spironolactone 1 to 2 mg/kg per day divided 1 or 2 times daily.     Results: Table 1 showing patient Demographics and Preoperative, Intraoperative, and Postoperative Parameters for the Entire Cohort According to Exposure to Preoperative Diuretics     Preoperative Diuretic Use and Impact on CS-AKI The incidence of CS-AKI in infants within 24 hours after CS was 49.7% (149/300) with 122 (41%) patients meeting the SCr criteria, 17 (6%) patients meeting the oliguric criteria, and 10 patients satisfying both criteria, among the patients who developed CS-AKI, the severity was stage 1 in 53.7% (80/149), stage 2 in 38.2% (57/149), and stage 3 in 8.1% (12/149). Both older age and weight at the time of surgery were associated with an increased incidence of CS-AKI. Tetralogy of Fallot was the only diagnosis with a significantly increased risk of AKI among those operated on in our cohort (CS-AKI 43 [72%], no CS-AKI 17 [28%], P=0.0005). Exposure to diuretics preoperatively did not increase the risk of AKI post operatively early after cardiac surgery.   Risk Factors for Moderate to Severe CS-AKI A total of 69 patients were diagnosed with moderate to severe CS-AKI. Univariate analysis demonstrated that the diagnosis of moderate to severe CS-AKI relative to no AKI or stage 1 AKI is significantly associated with Aristotle Complexity Score, CPB time, cross-clamp time, heart block, cardiac arrest, postoperative extracorporeal life support, and mortality. Preoperative diuretic use was significantly associated with mild or no CS-AKI. Multiple logistic regression showed that a diagnosis of TOF and longer CPB time are associated with an increased risk of moderate to severe CS-AKI   DISCUSSION Operative factors such as surgical complexity, CPB time, cross-clamp time, and use of inotropes have been described to contribute to the risk of postoperative AKI along with an increased risk of developing chronic kidney disease (CKD). The incidence of AKI in this population of infants undergoing CS was found to be 49.7%. This represents a high proportion of AKI cases in this population. Results suggest that preoperative diuretics do not increase the risk of postoperative AKI early after CS in infants with no history of renal dysfunction. The authors assessed early AKI only within this first 24 hours after CS and the onset of AKI beyond the first postoperative day was not assessed.   CONCLUSIONS The authors have found that preoperative use of diuretics in infants with no history of renal dysfunction for management of CHF does not increase the risk of postoperative CS-AKI early after CS. The only independent variable that increases the risk of CS-AKI is a diagnosis of TOF. With respect to CS-AKI severity, a diagnosis of TOF and longer CPB time are both risk factors for moderate to severe CS-AKI.