 CVCs can be mistakenly placed in an artery during insertion (for example, the carotid artery or vertebral artery when placed in the neck or common femoral artery when placed in the groin).This error can be quickly identified by special tubing that can show the pressure of the catheter (arteries have a higher pressure than veins).In addition, sending blood samples for acidity, oxygen, and carbon dioxide content (pH, pO2, pCO2 respectively) can show the characteristics of an artery (higher pH/pO2, lower pCO2) or vein (lower pH/pO2, higher pCO2).