What type of cannula is inserted into an artery and connected to a monitor?

The type of cannula that is specifically inserted into an artery and connected to a monitor is an intra-arterial cannula. This device is used for directly measuring blood pressure within the arterial system and facilitates the collection of arterial blood samples for laboratory analysis, particularly useful in critical care settings.

Intra-arterial cannulas provide real-time monitoring of a patient's hemodynamic status, which is crucial for managing critically ill patients or those undergoing major surgical procedures. They are also used for administering medications or fluids directly into the artery, although this is less common than monitoring purposes.

The other options provided refer to different types of access devices. An implanted port is typically used for long-term intravenous access but is not inserted into an artery. A central venous access device is inserted into a central vein rather than an artery and is generally used for administering medication or fluids. An internal catheter is a more general term that could refer to any type of internal tubing but does not specifically indicate arterial access.