When the doctor/nurse takes blood from you, why do they try to find a vein, not an artery? And also why is this mainly done on the arm as opposed to other parts of the body?
In: Biology
My veins can tell when I walk into a lab. “Dive, Dive, Dive” — they head for the deeps. Last time I gave blood, it took three different people to get me going. They were almost ready to give up. Once, I had blood taken from the back of my hand — no sweat. Quick, easy, low pain. Don’t know why they don’t do it more often — professional pride?
I had a grueling stent of almost 3 months in the hospital with necrotising pancreatitis. At one point I had 3-4 IVs at one time and they finally gave me a a Picc line for IVs, meds, and blood draws. When I was released after 37 days (tour 1)I had the wimpiest veins ever. So when I ended up back in the ER a couple weeks later (related reasons) they couldn’t get a vein to start an iv in my arm, they kept “blowing out” (not sure the technical term) and I was screaming and crying in pain. They tried multiple stabs, ultrasound guided, nothing worked.
So they had to use the top of my foot. Not ideal I’m told. but when your pancreas is exploding and you’re in the worst pain of your life, anything to get the show on the road 🤷🏻♀️
ED nurse here. I second the comments about arteries being deeper and harder to control the bleeding with. When you think of the body’s anatomy, an arm is much closer than a foot in relation to the heart. Veins in the feet tend to be small and fragile, meaning if you insert an IV line with the purpose of delivering intravenous fluids or medications, it may take slightly longer to take effect. Fragile veins also tend to collapse easily, meaning you’re more likely to have to repeat the procedure elsewhere, which takes time and increases the risk of infection. The cannula goes directly into the vein so walking around with an iv line in your foot is certainly going to increase your chances of transferring an infection to the site, as opposed to an arm.
In a resuscitation scenario, you want a big vein, close to the torso like by the elbow joint or higher where it can be absorbed quickly and effectively.
We try to choose a vein that is more practical for a patient when we have the opportunity. The patient’s capabilities are taken into consideration also. A confused, restless person probably will bump or pull out a line in their hand more than maybe say their elbow or elsewhere.
There are times when people simply have difficult, fragile, rolling or spidery veins. In those cases we try wherever we can and use various tricks like heat, fluids an ultrasound to help find the best vein.
I hope this helps!
Vein because Arteries are under pressure every time your heart beats. Its much cleaner the to take from a vein, because even when they do bleed they “ooze”, arteries “spurt”. Arm, because it’s convenient for patient and HCP.
Arteries constrict when traumatised, are generally (not always) located deeper in tissues, and are more elastic so they can deflect from the needle, this makes them much harder to hit.
They also bleed a heck of a lot more, which can lead to bruising/haematoma more easily if the stick isnt clean.
You can absolutely draw blood from arteries though, and there are several useful bits of information you can only get that way!
Doc here.
You can take from both. And the biochemistry in terms of blood gases (oxygen and CO2 content) and pH varies slightly. Some instances such as deciding on invasive ventilation and assessing respiratory function require a arterial sample.
However downside of arterial sampling is that the walls of arteries are innervated (I.e. have nerves including pain nerves in) in contrast to veins. They’re also much deeper. So taking an arterial sample is often much more painful. To the point some guidelines suggest using local anaesthetic. However in practice this is rarely done.
In regards to taking from the arm. It’s often not too painful and accessible. Other options include legs and in case of large veins in the neck (internal jugular) and groin (femoral). However larger veins require more care as often run with important structures that you don’t want to damage, such as the carotid or femoral artery.
Getting a suitable vein can get very difficult classically in IV drug users who use their own peripheral veins so much they clot off. Then I’ve seen creative placements such as even head veins (the type that bulge on typically very angry men) and veins running over the chest. To the point I once had a cardiologist boast that he’d put a cannula (the plastic tubes we put in veins to give drugs) in all the surface veins, apart from one. The dorsal penile vein. At that point all the men in the room we’re like “I’m out”
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