IV administration question

[another student]

I have an IV question that I was hoping you all can answer. We are doing pediatrics right now (I am a student) and they are doing the math for IV's. Since the amounts of the medication is is so small for peds I understand that you have to make sure to flush the tubing. My question involves the rate in which they infuse the medication. We figure out the exact amount of medication that we have to infuse, say 10ml. Then instead of calculating the rate based on that, say it is supposed to be infused over 1 hr, they say we should add the volume of the flush as well, 10 ml meds +5ml flush over the same time period. Isn't this going to be too fast of an infusion rate if it is supposed to be infused at 10ml/hr? Why wouldn't you just set the rate at 10 ml/ hr and then just put the volume to be infused as 15 ml? Isn't 15 ml/ hr going to be too fast? I am hoping that you all can explain this for me.

[NotReady4PrimeTime, RN]

You also have to factor in the volume of IV fluid in the dead space between where you are putting your med and the patient. Some infusion pump tubing sets have huge volumes; the Alaris Signature pumps we use (until October when we're getting Smart pumps) require at least 20 mL of fluid to prime them, and more if you're adding a filter or any other additional length. So when you put the med into a burette the rate has to be fast enough to get the med to the patient in the alloted time. Antibiotics, for example, are given at fixed intervals so that the level of drug in the patient's blood stays relatively the same. If I put my cefazolin into the burette and the base rate of the IV infusion is only 5 mL, it would take at least 4 hours before the patient started getting that cefazolin unless I speed up the infusion rate. See what I'm saying? What your instructor is telling you is that you have to also think about the amount of med left in the tubing when your recommended infusion time is done. Why do we flush after we give meds? To make sure the patient gets it all. So unless you use a port somewhere along the length of the tubing set-up, which is acceptable practice in most places, you have to calulate your rate based on getting ALL of the drug to the patient in the recommended time... and that includes your flush. Does that make sense?