A very important task at the start of a case that requires an arterial line, is to flush and prepare the arterial lines (drip lines) that will be used. These types of lines are used to provide flow through equipment (such as a femoral access sheath) so that a thrombus does not form during the case (from static blood flow). Ironically, while these drip lines help prevent embolic neurovascular events, if the are not prepared properly prior to usage, they can introduce air bubbles into the system (which can cause an air embolism).
As a result, special attention must be taken to make sure the line is flushed vigorously and is free of any air (before it is used). The video below shows the appropriate technique.