There are 2 types of CVCs, tunnelled and non-tunnelled: Non-tunnelled catheter access is for short-expression access (as many as about two weeks) as well as the catheter emerges directly from the skin at the location of entry in to the vein. The tunnel acts for a barrier to invading micro organism. https://dialysis91121.wikibriefing.com/3197885/5_easy_facts_about_dialysis_described