Veins vs. Arteries

Specialties Infusion


Kind of a silly question, or it makes me feel that way.

I've been doing IV's for 3 years, but recently I've been getting a lot of bright/red blood return when my IV's. I palpate for pulsation, check for valves, follow basic anatomy with my insertion. What is the science behind this? Some IV's I place, I have the dark venous blood return. While others, it is bright red, and looks arterial. It has me a little freaked out at the moment, making me doubt my IV skills.

For example: I placed a right forearm IV. I visualized/palpated the vein, no pulsation, and it was definitely the cephalic, it was just below the surface, painless insertion. The blood return was BRIGHT red. Maybe it is all in my head? ;)


Specializes in Vascular Access.

When Hgb is reduced, as it is in venous blood, the darker red color is prevelant.

However, there are times when it will appear brighter like when venous blood is exposed to air, or when venous blood is mixed with saline. In both of these cases, the cyanotic color will appear brighter red. Also, how much oxygen is in a venous sample? Usually small amounts, but every once in a while you'll get someone with higher amounts left in the specimen. Individuals with Dehydration, COPD pts, or those with Polycythemia Vera have higher levels of Hgb.

Does this help?

To cannulate an artery is actually not very easy, well at least when placing unguided peripheral IVs. The tunica media for arteries is much thicker than veins and is usually not as easy to pierce, let alone thread the catheter. When you cannulate an artery there is usually no doubt, it really tends to be fairly obvious.

Fluid status, temperature, Hgb level, certain diagnosis, and medications can all have a significant impact upon blood color.

If you have any doubts then simply draw some blood and run a stat ABG.

Specializes in Vascular Access.

Except, when one has an abberant artery... (and some sources stated that 1 out of 10 people have one) this is an artery which is superficially located, in an unusual spot. Also know that it is much easier to cannulate an artery in an emaciated patient. However, Asystole was right in the respect that there are factors other than above which play a part in the color of blood.

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