Peripheral intravenous catheters are the use of peripheral veins to implant some catheters in order to complete intravenous infusions. Peripheral intravenous catheters are currently available as scalp steel needles, peripheral trocar needles, and midline catheters, all of which operate in our arms, whether they are on the back of the hand, forearm, or upper arm for puncture. Scalp steel needle is only suitable for single infusion treatment and short time infusion treatment, because scalp steel needle is a sharp instrument, relatively speaking, will pierce the blood vessels as well as the operator; trocar needle is the use of steel needle through the trocar into the body while the steel needle is withdrawn, so that buried into the body is a hose, can be used for 3-4 days of retention time while infusion; at present in the clinic, there are some midline catheters, midline catheters The duration of use will be longer, because with the improvement of the level of puncture technology, it can be implanted from the peripheral blood vessels to the location of the axillary vein under ultrasound guidance, so it can also solve the problems that cannot be solved by the trocar needle, and the duration of use will be longer, so that it can meet the needs of other types of patients.