Which sign would indicate cannula displacement at an arterial line site?

Which sign would indicate cannula displacement at an arterial line site?

• A. Swelling
• B. Purulent drainage
• C. Pyrexia
• D. Pain with redness

Answer: (A)

Displacement of an arterial cannula is best detected by swelling at the insertion site. When the cannula moves out of the artery or leaks into surrounding tissue (infiltration or hematoma), blood accumulates in the nearby tissues, causing noticeable swelling. This local, tangible change is a direct clue that the catheter may no longer be in the correct place.

Purulent drainage points to infection at the site, not displacement. Pyrexia (fever) suggests systemic or local infection rather than catheter position. Pain with redness can reflect irritation or inflammation, but it isn’t as specifically tied to the catheter moving out of the vessel as swelling from infiltration is.