Arterial catheterization is a way to take very accurate blood pressure measurements – more so than by using a blood pressure cuff. A thin hollow tube, called the arterial catheter, is placed into the artery (the blood vessel which carries oxygenated blood from the heart to the rest of the body) of the wrist, groin, or any other part of the body and used to take the blood pressure. It can also be used to take blood samples when it is necessary to measure the oxygen or carbondioxide content of the blood.

Knowing the precise blood pressure is very important for doctors, because with that information they can decide on the smallest amount of medication needed to get the blood pressure up. Medicines for low blood pressure is very powerful; they stimulate the heart itself, making it pump faster. If too much medication is used, it can lead to unpleasant side effects, therefore the lowest effective dosage must be used.

The catheter usually stays in the patients’ artery for as long as needed, although most hospitals change the tubes every 5 days or so. They are like any other intravenous line and most patients, with assistance, can sit up and move with it attached.