Tunneled central venous catheters (CVCs) are now used routinely in pediatric hematology and oncology patients. Flushing with heparin solution is routinely recommended to prevent occlusion of long term CVCs, although the concentration of heparin used, and frequency of its use varies between centres. Once weekly Normal saline is also used successfully in some pediatric enters. There is little evidence to support one method over the other.~The investigators have designed a randomised crossover trial to directly compare once weekly Normal saline flushing with 3 times per week 10U/ml heparin flushing, to determine whether Normal saline is not inferior to heparin.
The purpose of this study is to determine whether flushing Central Venous Catheters (CVCs) with Normal saline once per week is not inferior to flushing with 10U/ml heparin 3 times per week, in preventing CVC occlusions.