A catheter assembly includes a multi-lumen catheter and fluid supply apparatus for supplying fluid to said multi-lumen catheter. The fluid supply apparatus includes an inlet element for coupling to a supply of catheter fluid, a plurality of fluid outlet elements arranged to be each coupled to a respective lumen of the catheter and a flow splitter arranged between the inlet element and the outlet elements. The flow splitter is able to split or divert flow of fluid from the inlet to at least one of the plurality of outlets. For this purpose, the preferred embodiment includes a gate for directing fluid flow to one or more of the outlet elements. There may also be provided a diffuser and a nozzle.