Rationalization from pre ana exam

• A vein can collapse when


  torniquet is tied too tightly or too close to the venipuncture site

  torniquet is removed during the draw

  if the vacuum draw of a tube or the pressure created by pulling on a syringe plunger is too much for the vein
• A tube can lose its vacuum during a venipuncture if the needle bevel is not completely under the skin.
• What should you do if you fail to establish blood flow during a draw and repositioning the needle doesn't help?

  Try using a new tube before giving up on the draw, as it could be a vacuum problem
• Elderly patients are fragile and have veins that collapse more easily.
• A clue that a normally visible vein has collapsed is that it disappears as soon as the tube is engaged or when the torniquet is removed.