Assessment of fluid status in neonatal dialysis: the need for new tools

A baby girl was born via C-section at 37-week gestation. Birth weight was 2.19 kg. She is the product of an IVF pregnancy, donor egg and sperm, born to a 43-year-old G3P0 with 2 prior miscarriages. At 18-week gestation, it was discovered that the baby had bilateral renal agenesis. Mother had chorionic villus sampling at 20-week gestation, which revealed normal karyotype XX. She was treated with serial transcervical amnio-infusions (twice weekly) to minimize pulmonary hypoplasia.

The mother’s past medical history is significant for MTHFR mutation and Factor V Leiden. She was on aspirin and enoxaparin during the pregnancy. She was admitted to an outside hospital after a failed amniotic infusion. There was an amnion chorion separation that day that prevented further attempts at saline infusions. Even with small contractions, the baby had variable decelerations to as low as 50 beats per minute. C-section took place, and the baby was born vigorous with Apgar scores of 8 and 9. She required only transient blow-by oxygen and was transferred to the NICU. She remained on room air, with peripheral intravenous catheter in place.

On day of life (DOL) 3, peritoneal dialysis (PD) catheter and gastrostomy tube were placed. Patient received intravenous cefazolin prophylaxis in the operating room. Two days later, vancomycin was initiated due to increased erythema around surgical incision site. Site culture was negative. Four days after PD catheter placement, the patient was started on hourly low volume PD exchanges, continuously over 24 h. Fill volume was initially 10 mL (4.5 mL/kg) for 6 exchanges, then increased and maintained at 15 mL (6.8 mL/kg). Dialysate used was 2.5% dextrose solution medicated with heparin 500 units/L. Despite this low fill volume, the patient developed a dialysate leak at the catheter site at 10 days of age. Hourly PD exchanges were held and PD catheter was locked with heparin. An 8 Fr by 18 cm left internal jugular tunneled hemodialysis catheter was placed, and dialysis modality was changed to daily 3-h hemodialysis (HD) sessions using a low flux polysulfone dialyzer membrane (Hemoflow F3 — Fresenius). The circuit, including the filter and tubing, had a volume of 47 mL and a blood prime was used. Dialysis prescription consisted of a blood flow rate of 14 mL/min (6.4 mL/kg/min), a dialysate flow rate of 300 mL/min, and net ultrafiltration (UF) obtained was between 100 and 160 mL per treatment (17 to 23 mL/kg/h or 50–70 mL/kg per session), adjusted daily based on traditional volume assessment parameters such as blood pressure, weight change, and evaluation of intake/output.

The patient’s weight at time of initiation of HD was 2.5 kg; however, dry weight was estimated to be 2.2 kg. After 6 days of daily HD, patient had achieved a weight of 2.36 kg, suggesting improvement in fluid balance. Intake/output balance was positive 50–100 mL/day (21–41 mL/kg/day). Total fluid intake was increased to 100 mL/kg/day on DOL 15 and increased further to 120 mL/kg/day on DOL 17. On DOL 18, PD was reattempted; however, catheter had inflow obstruction and the PD nurse was unable to infuse dialysate. After manipulation with manual flush, low volume PD exchanges with the goal to maintain patency of the catheter were resumed (10 mL fill volume = 4.5 mL/kg). While on these hourly PD minimum exchanges, daily HD was continued. The daily UF obtained with PD was 40–50 mL/day. On DOL 19, UF goal for HD was increased to 75 mL/kg as the patient’s pre-HD weight was increasing too fast, now 2.68 kg. On DOL 20, pre-HD weight was 2.62 kg despite UF the day before of 80 mL/kg and net fluid balance of + 75 mL. UF goal was increased further to 85 mL/kg for HD treatment on DOL 20. Of note, pre-HD BP was higher at 104/62 prior to HD on DOL 20. PD catheter leak recurred so PD exchanges were discontinued. At 3 weeks of age (DOL 21), the patient had increased work of breathing and required intubation. Chest x-ray was performed and revealed bilateral pulmonary edema and an enlarged cardiac silhouette (Fig. 1A and B). As her respiratory status worsened, she required intubation. Within 2 h of intubation, she was converted from conventional ventilation to high-frequency ventilation.

Fig. 1figure 1

A, B Chest x-ray of infant born with bilateral renal agenesis on day of life 8 (A). Chest x-ray of infant at 3 weeks of age in respiratory distress (B)

Differential diagnosis for patient’s acute decompensation included:

a.

Septic shock

b.

Respiratory event (pneumonia, mucous plugging, pneumothorax)

c.

Acute decompensated heart failure

d.

Volume overload

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