(This information about veins is found in
Gray's Anatomy and Guyton's Physiology as well as other A&P texts used at
the graduate or medical school levels. This advanced information is not currently taught in your programs.)
The walls of all blood vessels are innervated. This means they
have nerve endings - just like your skin! And just like your skin,
these nerves will respond to hot / cold / touch / pain in a specific and predictable manner.
on the stimulus, the nerve endings tell the muscle
in the wall of a vein to either relax or contract causing either vasocontriction or vasodilatation.
- dilates Touch (gentle) - dilates
Cold - constricts Pain - constricts.
Vein walls are INNERVATED!
What does this Anatomy Physiology of the vein have to do with vein access? EVERYTHING
How many times you have seen someone smack, slap, flick, or tap the site when trying to
locate a vein? These stimuli are interpreted as pain to a nerve ending, and . . .
Pain causes vasoCONSTRICTION - the exact
opposite response you were trying to achieve.
You want vasoDILATATION, so you need to palpate to dilate the vein. Our palpation technique will dilate the vein - even without the
use of a tourniquet!