I am mainly looking at why we are experiencing flow problems with our catheters. Is it the brand of the catheter or is it the technique of inserting them?
Most probaly, both. In my opinion, brands are important in means of catheter rigidity - the softer ones usually have much less problems, but again - the softer ones are more difficult to insert. Technique itself is also important - correct positioning of the catheter tip is crucial. If the tip contacts the side of the blood vessel, you'll have a problem very soon - it should be "hanging" free. I will deliberately avoid naming the "good" ones and the "bad ones", but the general rule is - don't go for cheapest ones!
Failure of a permanent (cuffed) CVC can be either immediate (manifested by inability to provide blood flow of at least 300 ml/min during the first postinsertion HD session - see the K/DOQI guidelines) or late. For the latter case, the gradually deteriorating performance of the CVC can be evaluated by measuring pressure/flow characterics of both its arms - see eg. Besarab A, Pandey R: Catheter Management in Hemodialysis Patients: Delivering Adequate Flow. Clin J Am Soc Nephrol, 2011; 6:227-234). With such measurements being done in regular, say one month intervals, it is possible to try some cleaning procedure to remove the fibrin sheet or clots inside the CVC before it gets completely clotted.
F. Lopot, Prague