stringe size for arterial lines

We rarely lose an art line before it's time to pull it. The ones we lose are usually thooe that have been dislodged by a wild child (or a slightly too aggressive dressing change!). We use all sizes of syringe to draw bloodwork, from a 1 mL heparinized gas syringe up to a 20 mL for transplant workups; our patients range from neonates to virtual adults, cardiac, trauma, respiratory and all stops in between. We reinfuse the "waste" drawn off at the beginning. I've also used 3 mL, 5 mL and 10 mL syringes to flush with when the patient's art line is on a pump and not on a pressure bag. Are your flush solutions heparinized? I just glanced at a lit search reported in the AJCC that suggests more lines are lost if the flush solution infusing isn't.