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A machine for haemodialysing very small infants

Lookup NU author(s): Dr Malcolm Coulthard, Dr Michael Keir


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Babies weighing under 6 kg are difficult to dialyse, especially those as small as 1 kg. Peritoneal dialysis is easier than haemodialysis, but is not always possible, and clears molecules less efficiently. Two factors complicate haemodialysis. First, extracorporeal circuits are large relative to a baby's blood volume, necessitating priming with fresh or modified blood. Second, blood flow from infants' access vessels is disproportionately low ( Poiseuille's law), causing inadequate dialysis, or clotting within the circuit. These problems are minimised by using single lumen access, a very small circuit, and a reservoir syringe to separate the sampling and dialyser blood flow rates. Its manual operation is tedious, so we developed a computer-controlled, pressure-monitored machine to run it, including adjusting the blood withdrawal rate from poorly sampling lines. We have dialysed four babies weighing 0.8 - 3.4 kg, with renal failure or metabolic disorders. The circuits did not require priming. Clearances of creatinine, urea, potassium, phosphate and ammonia were mean (SD) 0.54 (0.22) ml/min using one dialyser, and 0.98 ( 0.22) ml/ min using two in parallel. Ammonia clearance in a 2.4 kg baby had a 9 h half-life. Ultrafiltration up to 45 ml/h was achieved easily. This device provided infants with immediate, effective and convenient haemodialysis, typically delivered for prolonged periods.

Publication metadata

Author(s): Everdell NL, Coulthard MG, Crosier J, Keir MJ

Publication type: Article

Publication status: Published

Journal: Pediatric Nephrology

Year: 2005

Volume: 20

Issue: 5

Pages: 636-643

ISSN (print): 0931-041X

ISSN (electronic): 1432-198X

Publisher: Springer


DOI: 10.1007/s00467-004-1785-5


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