Large veins can sometimes be deceptively hard to cannulate, it may be because the vein ‘rolls’ and the needle therefore misses. Sometimes it helps to more forcefully ‘trap’ the vein with a finger while needling. Also it may be because the vein is hardened from being used, and more force is required to get the needle in. It may pay to give that vein a rest for a while and try a different vein (if this is possible). Also make sure that the angle of the needle when penetrating the skin is at the correct angle.
This is not an unusual problem, it pays to be patient and not get frustrated.
Answered by: Nurse