The document discusses the arterial line insertion procedure. It notes that arterial lines are used in critical care patients to easily obtain blood samples, avoid frequent needle pricking, and estimate cardiac output. The procedure involves inserting a catheter into an artery, such as the radial artery. Potential complications include pain, bruising, infections, air embolism, blood loss, hematoma and bleeding. Ultrasound guidance and local anesthetic can increase success and reduce pain of the catheterization.