I was given an injection with a baby needle on my elbow pit. The nurse had to switch veins 4 times (twice in left arm, twice in right arm) and still didn’t manage to give me the injection. I was told it was because I felt nervous so it made my veins “disappeared”. How is that possible ?
In: Biology
So, from a theoretical perspective:
Your body goes through something called sympathetic stimulus during stressful situations – it is colloquially called a “fight or flight” reaction. The body does several things with this, it reduces blood flow to your gut (don’t need to be digesting things when running from a tiger), activates insulin (to get glucose into your muscles, where you are gonna need it to run from a tiger), dilated the pupils (so you can see the tiger better), increases blood flow to your heart, and increases heart rate (definitely need that with tigers around), and *decreases* peripheral blood flow (to prioritise the central organs, like your heart and lungs) by constricting your veins. Smaller tubes, less blood in them, more blood for your heart. This increases your blood pressure too.
From a practical perspective, the venous constriction is actually relatively small, certainly compared to other factors affecting how easy it is to get a needle in, like hydration.
Your nervous disposition also has an effect on the person putting the needle in. I am massively needle-phobic, and I really hate cannulating other needle-phobes, cos I know what they are going through, and it makes me feel under massive pressure to get the vein first time, which inevitably makes me miss.
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