Peripheral vascular (vein & arterial) catheter
1. typically 16–20 gauge catheters that are 1–2 inches in length.
2. inserted using a catheter-over-needle device
3. Flow Characteristics in Peripheral Vascular Catheters
4. intended for short-term use (hours to days) because the plastic polymers provoke a strong inflammatory reaction and it's easy to dislodge
Central venous catheters
1. length: 15-30cm；The 20 cm catheter is long enough for most cannulation（including the left-sided）
2. triple-lumen catheters are the most popular
3. Size：These catheters are available in diameterss of
4 French to 9
French, and the 7 French size (outside diameter = 2.3 mm) is a popular choice in adult
4. insertion technique:
seldinger technique
1) guide wire through needle access
2) dilation of the tract
3） cannulation over the wire
4） removal of the guidewire