med 18

 

53.4). The arteriovenous pressure gradient frequently produces adequate blood flow through the circuit; however,

the addition of a blood pump may be necessary. As blood

flows through the extracorporeal device, plasma water and

dissolved solutes are filtered out (ultrafiltered) through the

pores of a hemofilter. A hemofilter is composed of many

fine capillaries of highly water-permeable membranes,

located within a cylindric case. The filtered-off fluid (ultrafiltrate) is drained out by way of an exit incorporated on the

surface of the hemofilter. The fluid removed has all the

characteristics of an ultrafiltrate of plasma water.

Except when it is incorporated in an extracorporeal

membrane oxygenation circuit for ultrafiltration, CAVH

has been widely replaced by CVVH/D. It is used effectively

in neonates with inborn errors of metabolism (33). Two

single-lumen catheters (or one double-lumen venous catheter) are used for vascular access in CVVH/D. Blood flow is

maintained by a pump and is, therefore, independent of the

patient’s systemic blood pressure. Several brands of CVVH

machines are currently available for CVVH/D (34).

References

1. Blatz S, Paes B, Steele B. Peritoneal dialysis in the neonate.

Neonatal Netw. 1990;8:41.

2. Stapleton FB, Jones DP, Green RS. Acute renal failure in neonates: incidence, etiology and outcome. Pediatr Nephrol. 1987;

1:1314.