AKI stages A retrospective pediatric study of over 500 infants after cardiac surgery assessed a version of the FST, where UOP was assessed at 2 and 6 hours after a diuretic challenge.34 This study found that patients who had UOP of at least 1 mL/kg per hour were very unlikely to develop AKI Taken together, these studies suggest that a standardized, objective assessment of diuretic responsiveness can aid in the prediction of AKI development or worsening severity When diuretics are unable to achieve fluid and electrolyte homeostasis, escalation to the provision of renal replacement therapy (RRT) is warranted Determination of the optimal timing of RRT initiation has been a major focus of study in the field of critical care nephrology with conflicting outcomes,35–37 but recent studies in the pediatric cardiac surgery population have provided some positive results However, it is important to dispel the notion that RRT itself causes irreversible kidney damage and failure Nearly 20 years ago, one study demonstrated increased urine output after peritoneal dialysis was initiated in 20 infants after cardiac surgery.38 A second study randomized patients to continue versus discontinue peritoneal dialysis (PD) after a positive diuretic challenge, and found no differences in total negative fluid balance or concentrations of novel kidney damage biomarkers, and urine output continued to increase even in the patients randomized to PD continuation.39 Recent studies have examined the association between PD and outcomes after cardiac surgery in children (Table 78.6) In a retrospective analysis, Bojan and colleagues observed a nearly 50% decrease in patient mortality when PD was initiated on the first postoperative day versus later in the postoperative course.40 Two studies by Kwiatkowski and colleagues compared fluid balance, mechanical ventilation days, and electrolyte management in children who received PD catheter placement intraoperatively In each of these studies, PD catheters were placed intraoperatively based on patient characteristics that increase the risk of postoperative AKI development (Table 78.7).21,22 The first was a retrospective study of patients who received intraoperative PD catheter placement after the institution of risk-guided practice versus a matched historical cohort who did not receive a catheter prior to this practice Patients who received a PD catheter were able to achieve negative fluid balance in the first 48 hours more often, had lower rates of 10% fluid overload, were extubated 24 hours earlier, and had fewer electrolyte derangements than those without a PD catheter The second study was a prospective randomized study of the initiation of PD versus diuretics in patients with urine output of less than 1 mL/kg per hour for 4 consecutive hours in the first 24 hours after surgery Patients who received PD were less likely to develop 10% fluid overload, and to have prolonged mechanical ventilation and prolonged inotrope use Given the high incidence of AKI after cardiac surgery, these studies collectively suggest that PD catheters should be placed intraoperatively in high-risk patients to prevent severe fluid overload and to maintain electrolyte homeostasis in patients who develop oliguria and/or are diuretic resistant Table 78.6 Outcome Studies of Peritoneal Dialysis (PD) Provision in Children After Pediatric Surgery Study (Subjects) Sorof38 (n = 20) Bojan40 (n = 146) Riley39 (n = 20) Design Outcomes Retrospective Urine output increases on PD No deaths Decreased 30- and 90-day mortality in early PD group Retrospective cohort study of early (day 1) vs late (>day 1) PD Prospective randomized to PD continuation vs discontinuation Kwiatkowski21 Retrospective matched case: control of patients with vs (n = 84) without intraoperative PD catheter placement Kwiatkowski22 Prospective randomized PD vs furosemide (n = 73) Urine output increases in both groups after randomization No differences in urine AKI biomarkers between groups after randomization Patients with a PD catheter: (1) higher rates of negative fluid balance, (2) higher rates of prevention of 10% fluid overload, (3) lower rates of electrolyte disturbance, (4) extubated 24 hours earlier Patients randomized to PD: (1) less likely to develop 10% fluid overload, (2) less likely to have prolonged ventilator use, (3) shorter inotrope use, (4) fewer electrolyte abnormalities AKI, Acute kidney injury Table 78.7 Criteria for Intraoperative Peritoneal Dialysis (PD) Catheter Placement During Cardiac Surgery in Children Population High-risk patients: PD catheter placement planned preoperatively Moderate-risk patients: PD catheter placement considered based on clinical condition in the operating room Criteria Age 6 months Patients >4 months undergoing TOD/DORV repair Bypass time >120 min DORV, Double-outlet right ventricle; TOF, tetralogy of Fallot When intra-abdominal conditions exist and prevent the use of PD, recent studies have shown promise with various continuous venovenous dialytic modalities, either with machines that are adapted for this purpose,41 or with machines developed specifically for the neonatal population.42,43 Use of these technologies requires specialized nursing training and program development to guide volume management, as well as the various forms of anticoagulation needed to prevent circuit clotting Long-Term Renal Consequences of Cardiac Surgery–Associated AKI The association between AKI and the development of CKD has been the subject of increased clinical and basic study over the last decade.44 Pediatric survivors of an AKI episode provide an important population for study of the AKI to CKD interconnection, as they do not usually suffer from the same comorbidities, such as diabetes, cirrhosis, or chronic hypertension, that lead to CKD in adults.45 Furthermore, pediatric survivors of cardiac surgery–associated AKI provide a potentially more informative group to study, since they often only suffer the one episode of AKI around the time of surgery Recent studies in the pediatric cardiac surgery population do in fact demonstrate the association between AKI and CKD development (Table 78.8).8,10,46–48 These studies demonstrate a relatively higher prevalence of many CKD factors, including decreased glomerular filtration rate, microalbuminuria, and hypertension Interestingly, one study showed a persistent elevation in novel urinary kidney damage biomarkers, suggesting the presence of subclinical ongoing kidney damage 5 to 7 years after the cardiac surgery–associated AKI episode Unfortunately, it is well documented that standardized and comprehensive follow-up of AKI survivors for CKD development is not common practice.49 The development of AKI provides a unique opportunity to establish systems to follow patients for early signs of CKD, with the potential to slow or even prevent CKD progression.50,51 Table 78.8 Long-Term Outcomes in Pediatric Survivors of Cardiac Surgery–Associated AKI Follow-Up ... diuretic resistant Table 78.6 Outcome Studies of Peritoneal Dialysis (PD) Provision in Children After Pediatric Surgery Study (Subjects) Sorof38 (n = 20) Bojan40 (n = 146) Riley39 (n = 20) Design Outcomes... The association between AKI and the development of CKD has been the subject of increased clinical and basic study over the last decade.44 Pediatric survivors of an AKI episode provide an important population for study of the AKI to CKD... interconnection, as they do not usually suffer from the same comorbidities, such as diabetes, cirrhosis, or chronic hypertension, that lead to CKD in adults.45 Furthermore, pediatric survivors of cardiac surgery–associated AKI provide a potentially more informative group to study, since they often only suffer the one