Hemolysis From Drawing Laboratory Work Through an Intravenous Catheter Site

In adult patients it is generally agreed that catheters of a size of 18 gauge or larger are best to yield the lowest rates of hemolysis when drawing blood through an IV catheter. [...]what has been the secret of my success in this? I will not draw any laboratory test that is affected by hemolysis (most tests that are run off of serum plus all coagulants) with either a Vacutainer or syringe unless the vein is significantly larger than the catheter inside the vein, and almost never if the catheter size is smaller than a 22 gauge; I will not use a Vacutainer on any catheter smaller than a 20 gauge; and I always make sure I draw slowly enough that I never feel a "thrill" during the draw.