Each time you insert anything into a port you must clean the cap with an alcohol wipe. The site around the central line will need to be cleaned several times a week. This is done by using sterile supplies, wearing masks, and cleaning with alcohol and betadine swaps, then covering with sterile gauze and a waterproof covering. You can have multiple problem with a central line, but for the most part, they are easily prevented. Plus having a central line eliminates the need for many many sticks with needles for the many infusions.
Problems can be both internal to the line as well as external.
Blocked line - This can usually be prevented by flushing the line with saline and heparin as directed by the physician. Infection - Again, this can usually be prevented by clean care and regular flushes. They may come anyway and will need to be treated quickly. Usually blood tests are done on blood taken from both ports so that an infection in only one line can be detected early. Line coming out - This happened to Nicole once at 2am, luckily she was in the hospital at the time.