IVPB Question


Situation: I have a primary bag of NS infusing through a pump at 125mL/hr and I need to attach a secondary bag which has a medication in 50mL of solution needing to be infused at 100mL/hr. The piggybacks don't have lines of measurements so I can't verify if the bag has 50mL or more in it. I understand that when programming the IV pump, I program the settings for the primary line (rate and amount to be infused) and then I program the secondary line with the medication, mg of medication, mL of solution, and so on, and I double check to make sure the dose and rate match my calculations. I understand that the pump will count backwards from 50mL and once it hits 50mL it will go back to the primary line settings (in this case, 125mL/h). But what if the pharmacy DID send me a secondary bag with >50mL? Now medication will be administered at a different rate than what was ordered once the pump has infused 50mL. Should I automatically assume the pharmacy will send me the right amount of solution? Or should I assume the pharmacy sent me more than the ordered amount and should I set the amount to be infused of the secondary line higher? Thanks everyone for your responses.

Double-Helix, BSN, RN

1 Article; 3,377 Posts

Specializes in PICU, Sedation/Radiology, PACU. Has 12 years experience.

I'm not sure I am understanding. If you set the pump to infuse 50ml over half an hour, it will delievery 50ml. If the bag is filled with more than 50ml, the pump will deliver 50ml and the remaining fluid will still be in the bag. If there is less than 50ml in the bag, the bag will run dry and the pump will alarm. As long as you set the pump correctly, the patient will get the right amount of the medication.

Remember that the volume that you set the pump to infuse includes what is in the tubing, so if the primarytubing has normal saline, I will sometimes set the piggyback to deliver 52 or 53 mls to account for the fluid in the tubing so the patient gets the entire volume in the bag.

MunoRN, RN

8,058 Posts

Specializes in Critical Care. Has 10 years experience.

You are correct that there will be some of the secondary that will flow at the primary rate if you set the volume for 50. Even if the bag contains 55ml and you set it for 55ml, you'll still get about 10 ml that flows into the patient at the primary rate due to the volume of the tubing between the secondary port and the patient. When you program a secondary, all you are doing is programming the pump to run at a different rate for a specified period of time, it also will not subtract the volume of the secondary off of the VTBI of the primary.

Pharmacy can usually tell you how much they overfill bags by, and if you add that to the volume of the tubing between the secondary port and the patient then you can ensure that all the secondary fluid flows in at the appropriate rate, although I'm not sure it really makes any difference. Some nurses still run antibiotics with no pump, so the exact rate doesn't seem to be that imperative. It is important that most antibiotics not go in too fast or too slow, although I doubt that the difference between 125 and 100ml/hr for 10 or 15 mls makes any clinically significant difference.


17 Posts

Thank you for your responses. I'm doing my peds rotation this semester so I just wanted to be sure about the concept of piggybacks. I will continue to go to the skills lab and get even more comfortable with IVs. Thanks again!

Double-Helix, BSN, RN

1 Article; 3,377 Posts

Specializes in PICU, Sedation/Radiology, PACU. Has 12 years experience.

Okay, I think I understand a little bit more. Yes, there will be some of the med left over in the tubing that will run at the primary rate. However, this is only about 3-5mls and the rate difference won't matter.

Depending on the kind of pump you are using, this may not matter. There are two kinds of pumps that we use in PICU.

Without getting two complicated, one pump has space for three different lines. So you can run three seperate tubings into the same port on the line. So with this pump, the abx is delivered at the same time as the maintenance fluids. The abx tubing will deliver 50 mls at the programmed rate and then stop. No more will be delivered, as the tubing is not connected to the primary line.

The seond pump is a traditional primary line with a port to piggy back into the main line. So you can program the piggyback and while the abx is running, the primary stops. Once the piggyback has infused the set volume, the primary takes over again. So the little amount of abx left in the primary tubing is infused at the primary rate. Again, this is only a few mls and is really insignificant.

Specializes in Critical Care, Emergency Medicine, Flight.

if you have to infuse 50mL/30minutes.. for IVPB we were taught to program the pump for more..like say 60mL..so that it squeezes that bag dry and it will go back to the primary IVF. also..maybe there is also a little extra in the PB bag so when u are priming the tubing , the bulk of the dose isnt being compromised..if that makes sense.

nurseprnRN, BSN, RN

2 Articles; 5,114 Posts

the pharmacy mixes piggybacks in little iv bags, and they come from the manufacturer labeled as to how much there is in them, plus a few ccs. so you will know how much there is in there. if the pharmacy adds a significant amt of fluid to a bag, the bag label they put on will tell you that, too.