Circuit pressure
Pressure detectors are placed in both the arterial and venous side of the
circuit to regulate transmembrane pressures and allow adequate
ultrafiltration. Low arterial pressures may be due to hypotension, kinks in
the tubing system, catheter malfunction or stenosis of the arterial inflow.
Venous hypertension may be due to clotting of the dialyzer/membrane,
kinks in the tubing system or stenosis of the venous outflow.Vascular access for RRT
- Catheter location
Hemodialysis catheters should be preferentially placed in the IJ vein.
Femoral vein and SC vein are alternatives to IJ vein but are associated
with vein thrombosis and vein stenosis respectively. SC vein stenosis, a
common complication of dialysis catheters, is of concern because some
children will eventually require permanent vascular access for chronic
hemodialysis. - Catheter size
According to Poiseuille’s Law, the greater the diameter of the catheter, the
less resistance to flow. Long catheter should be avoided for this same
reason.
Catheter sizes vary from 7 to 12 F according to the weight of the child.
Neonates and children up to 6 kg usually require 7 Fr, 6 to 15 kg require 8
Fr, 15 to 30 kg require 9 Fr and >30 kg 10 Fr catheters. [3] - Catheter insertion
In neonates and small children, use cut down techniques similar to ECMO