Certain
inborn errors of metabolism become manifest during the neonatal period by acute accumulation of neurotoxic metabolites leading to
coma and death or irreversible neurological damage. Outcome critically depends on the immediate elimination of the accumulated
neurotoxins. Recent technological progress provides improved tools to optimize the efficacy of neonatal dialysis.
METHODS: We report our experience with continuous venovenous haemodialysis (
CVVHD) in six neonates with hyperammonaemic
coma due to
urea-cycle disorders or propionic acidaemia and in one child with
leucine accumulation due to
maple-syrup urine disease (MSUD), in comparison with five patients managed by
peritoneal dialysis (PD) (2 hyperammonaemia, 3 MSUD). Application of a new extracorporeal device specifically designed for use in small children permitted the establishment of stable blood circuits utilizing small-sized
catheters, and the tight control of balanced
dialysate flows over wide flow ranges.
RESULTS: Plasma
ammonia or
leucine levels were reduced by 50% within 7.1 +/- 4.1 h by
CVVHD and within 17.9 +/- 12.4 h by PD (P<0.05). Also, total dialysis time was shorter with
CVVHD (25 +/- 21 h) than with PD (73 +/- 35 h, P<0.02). A comparison of the
CVVHD results with published literature confirmed superior metabolite removal compared to PD, and suggested comparable efficacy as achieved with continuous haemofiltration techniques. Apart from accidental
pericardial tamponade during
catheter insertion in one case, no major complications were noted with
CVVHD. In three of the five PD patients, dialysis was compromised by mechanical complications. None of the MSUD patients but four children with
urea-cycle disorders died, two during the acute period and two later during the first year of life, with signs of severe mental delay. Of the eight children presenting with hyperammonaemic
coma, the four with the most rapid dialytic
ammonia removal rate (50% reduction in < 7 h) survived with no or moderate
mental retardation, whereas slower toxin removal was always associated with a lethal outcome. Simulation studies showed that the efficacy of neonatal
CVVHD is limited mainly by blood-flow restrictions.
CONCLUSIONS: