By the ultrasound-guided technique, it is possible to insert not only short cannulas in the deep veins of the arm, but also peripheral devices of greater length, such as mini-midlines (6-15 cm), which can stay in place, well functioning for 2-3 weeks (up to a month).
Mini-midlines may be of different materials; in the case of long duration - polyurethane catheters should be preferred to polyethylene (the latter being associated with greater risk of thrombosis).
There are mini-midlines to be positioned with simple technique (needle puncture - insertion of the metal guide into the needle - needle removal - catheter insertion above the guide) but also mini-midline with more complex design, in which needle, cannula and metal guide are assembled coaxially in an all-in-one device. At present there is no evidence to recommend the latter type of mini-midline, since they are more expensive and more difficult to use.