Case Study: Aquadex FlexFlow Provides Renal Support as Bridge to Peritoneal Dialysis

Baby B was born at 37 weeks and 4 days via vaginal delivery. He was found to be severely depressed with no spontaneous respiratory effort, requiring resuscitation in the delivery room, including intubation for respiratory failure and volume resuscitation for hypotension. APGARS assigned were low.

His initial NICU course was remarkable for:

• moderate to severe encephalopathy qualifying for therapeutic hypothermia
• hypoxemic respiratory failure requiring high-frequency ventilation and 100% oxygen
• persistent pulmonary hypertension requiring inhaled nitric oxide
• hypotension requiring fluid resuscitation and moderate inotrope support and concern for a possible abruption versus maternal-fetal hemorrhage given the baby’s pale appearance
• anemia, requiring red blood cell transfusion shortly after birth

Transfer to our Harriet and Ronald Lassin Newborn/Infant Intensive Care Unit (N/IICU) was initiated within 24 hours of birth for potential need for extracorporeal membrane oxygenation (ECMO) support. After admission, Baby B’s course evolved with coagulopathy requiring multiple blood products, concern for seizures requiring anti-epileptic therapy, evidence of multi-organ injury, and oliguric acute kidney injury (AKI) due to ischemic acute tubular necrosis. There was no evidence of infection.

The baby’s degree of renal dysfunction, continued oliguria, and progressive fluid overload (>3 kg above birth weight), despite fluid restriction and trials of diuretic, prompted discussion by a multidisciplinary team as part of the N/IICU’s Neonatal Renal Program to initiate ultrafiltration via Aquadex FlexFlow®. A femoral hemodialysis catheter was placed by the Interventional Radiology team and ultrafiltration was initiated on day of life 3. Aquadex was continued for a 10-day course. Initially, ultrafiltration was utilized to remove excess plasma water to help with fluid overload. For the latter part of the Aquadex course, modified hemofiltration was utilized to allow for fluid removal while correcting and stabilizing electrolyte imbalances. Improvement of Baby B’s AKI with recovery of adequate urine production and improvement in renal function allowed for discontinuation of therapy.

Aquadex FlexFlow® (CHF Solutions) is FDA approved for slow continuous ultrafiltration in adults with diuretic resistant heart failure. The system has been used in the pediatric population given the smaller circuit volume of 33 mls and slower blood flow rates, both of which are better tolerated in small patients. This allows for use of smaller vascular catheters, a 6 Fr power PICC being the more commonly used device in the NICU population. Complications with this therapy include transient hemodynamic instability (although less than traditional hemodialysis approaches in small patients), clotting, catheter malfunction, and minor bleeding.

The Aquadex circuit can be used for ultrafiltration or modified continuous veno-venous hemofiltration (CVVH). This approach to renal replacement therapy (RRT) in the neonate allows for support of small infants with early renal insufficiency or renal failure who are not yet able to receive peritoneal dialysis (PD). Aquadex can provide renal support as a bridge to when the patient is able to transition to PD. Thus far, we have utilized this therapy at CHOP for AKI and congenital renal anomalies with renal insufficiency and/or renal failure in patients as premature as 29 weeks gestational age and as small as 1.3 kg.

Baby B continued to improve and wean support. His course was additionally complicated by ileal perforation on day of life 10 requiring exploratory laparotomy and ostomy creation, with subsequent ostomy take down on day of life 47. He was discharged home on day of life 56 on room air, tolerating full enteral ad lib feeds, with sodium bicarbonate as his only medication. His MRI was reassuring. Baby B continues to be followed by multiple subspecialists at CHOP, including Nephrology, Neurology, Surgery, and Neonatal Follow-up, as well as Early Intervention and Physical Therapy.