Eli5: why does it hurt so much more to draw blood from an artery as opposed to a vein?


Eli5: why does it hurt so much more to draw blood from an artery as opposed to a vein?

In: Biology

As a nurse who has performed both countless times I’ve never heard this before. Is this personal experience?

There’s a few reasons. The big ones are that arteries are a bit deeper than veins, and there are more nerves nearby.

I’m assuming you’re referring to an ABG, where they drew blood from your wrist. In general that area tends to be sensitive, and even venous blood draws are more painful there than from the area near your elbow.

Arteries have thick muscular walls with nerve fibers interlaced among the smooth musclefibers, whereas venous walls are thin and relatively weak, so there is less resistance to a needle passing through.

Arteries have thicker walls and depending on where the sample is taken will be deeper then a vein. (Wrist artery pokes arent much more deep). Usually you go for an artery for an Arterial Blood Gas. Another factor that can increase the overall unpleasantness of an arterial poke is that they can be harder to get. You can’t see your arteries whereas you can visualize a vein a lot of the time. This means you have to go by feeling a pulse. Sometimes you are off and need to readjust the needle. This can lead to more pain. Also you might have to just repoke causing more both physical and emotional/ cause more anxiety in those that hate needles.

Source: Respiratory Therapist who draws arterial blood samples daily

Edit: As an addendum people have commented on being close to nerves. That will cause a wholly new sensation of pain and will be way worse, but wont contribute to the normal increased pain of an artery poke. If you’re trained in taking samples you shouldn’t be hitting the nerve near the common sampling sites. I never have and have heard few cases from coworkers who have.