Arterial access is one of the most commonly used invasive techniques in intensive care medicine. It could be a single puncture (for blood sampling) or the insertion of the  arterial catheter.

Any accessible artery can theoretically be cannulated, but we prefer places which are accessible, easy for nursing care, and we try to avoid "end arteries" (arteries without distal circulation), so we usually choose the radial artery.  Alternatively, the femoral or brachial artery are also commonly used.

Seldinger technique is the preferred method of cannulation, but over-the-needle technique can also be used.