You see it all the time in the films and on TV don’t you? Someone can’t get access to a vein so they give the arm a few sharp smacks. You’ll also see it in hospitals and doctors surgeries as well, which is unfortunate because it doesn’t work.
Veins like almost everything else in the body have nerves in them, and so they register pain. If you slap them they react the same way you and I do to pain, they move away from it and contract, making them smaller (OK not exactly the way you and I react, you and I might react by punching someone in the face, but veins lack the hands for this and so they contract.)
So why do some nurses and (especially) doctors still slap? Simple, it’s a learnt behaviour. Not during their training, but afterwards. During training nurses are taught to palpate a vein (more on this in a moment), but shortly after they start working on a ward someone will tell them they should ‘slap’ a vein, and so they do. Don’t think too badly of them for falling into this behaviour, peer education isn’t always a good thing. Just think of the amount of people who still lick needles because the person who showed them how to inject licked his. Nurses and doctors are just like the rest of us, only human.
Main thing is though, don’t slap.
Instead of slapping you should gently palpate a vein, here’s how:
Gravity if your friend, blood like everything else is affected by gravity (one of the reasons injecting in your feet is higher risk). Try lying on a bed or sofa with the arm you want to inject with hanging down over the side. This should increase the amount of blood in that arm, and as a result the veins will appear bigger.
Another way of using gravity is using centrifugal force. The easiest way to do that is to spin your arm around like a windmill. The force on your arm will mean blood still enters but has problems getting back out.
With these techniques, and any other ways of raising a vein, it’s important to be confident they’ll work. So try them out when you don’t need to inject, it’s a great way to practice so that when you NEED to use them, you’ll know exactly what you’re doing.
And if you are a member of staff in a needle programme or drug service, and you’ve never injected then you should try them as well. It’s so much easier to explain to people how to raise a vein if you KNOW it works (rather than just having read it on a website).