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secondary flush bags for antibiotics

Our pharmacy has recently been questioning our practice of administering antibiotics thru a primary/secondary system using a flush bag for intermittent antibiotics. They feel that we should be able to run the antbiotic thru a primary line and then attach a 10 ml saline syringe to the most distal port on the tubing and flush the rest of the antibiotic to the pt.(instead of a flush bag). I disagree with this for many reasons, one being that this does not follow the INS standard for primary and secondary infusions. Our pharmacy states that if we continue the current practice of a "flush " bag that we would have to change the flush bag  every time we reconnect the tubing to the pt. as the flush bag is only a "single use" bag according to the Iowa Board of Pharmacy. We currently do change the bag and tubing every 24 hours.

Has anyone else heard of this practice of changing the flush bag every time?

How many of you are using a primary tubing to administer antibiotics and then flushing thru a "port" with 10 ml saline flush? If so, what evidence do you have to support this practice?


Medication administration

We base our practice on the INS Standards and so, like you, change our intermittent sets every 24 hours. We began our practice of using a small bag of solution to flush with a change in our IV tubing (and this may help with your arguement). Our continuous infusion tubing contains nearly 25 ml of fluid, whe you are only administering a medication from a 50 mL bag, clearly 50% remains in the tubing and does not get to the patient. Flushing with 10mL thru an access port still does not acheive 100%, so we went with a secondary bag for flushing. I hope this helps you.

Kim Mills


Random VAT person
It sounds like Pharmacy is

It sounds like Pharmacy is focused on one use.  Unless you attach the bag then disconnect the bag, then reattach the bag to the line it would still be one use.  The line is multi use for 24 hr.  :)  I hope that helps.  and I agree with Kim, there is still fluid in the line so their argument is not true.


jill nolte
just a comment

I had a pharmacist tell me that fluid in iv tubing should be forward flow only and back flushing the secondary tubing was bad practise.  I presented the question and got an answer on this forum.  The process that we are using is per the manufacturer's recommendation.  Your question is similar and you might find your evidence for practise with the manufacturer.

definitely part of the dose will be in tubing above the port, expecially if there is a cassette that holds a considerable volume.

 As a general rule,

 As a general rule, pharmacists do not have knowledge of the logistics of actually infusing medications. I have never used a carrier fluid to flush the IV set after the ABX has infused through a secondary IV set attached to the primary set. I do know of hospitals that use this technique. I think this became a huge issue when we started infusing all intermittent medications with an infusion pump. The pump set will hold a lot more fluid than a regular set. I also strongly agree that the secondary set should never be detached from the primary set after each dose to allow for manual flushing. And that the distal injection site would not be appropriate to flush all of residual meds from the primary set. The pharmacists is correct that all IV fluid containers are labeled as a single use container. I would be more concerned about using this carrier fluid on all patients since some would have fluid restrictions, etc. Do you require a physician order for this carrier fluid or is this written as a hospital policy and procedure? You would definitely need to have one of these methods. I am not aware of any published evidence to support either technique. We defintiely do not have any studies on any IV set used for intermittent infusion. There is nothing in any standard or guideline any more stating that a fluid container should be changed at 24 hours. This is the original standard established in the early 1970's following a nationwide outbreak of BSI that was tracked to the closure on one brand of IV bottles. I am not aware of any studies since then that have examined this 24 hour time limit on fluid containers. Is there a documented problem with any type of infection where this practice has been thought to be the cause? If not, it would appear the pharmacy is creating a problem where there is none. I would urge you to involve the infection prevention dept and also risk management on this issue. Lynn

Lynn Hadaway, M.Ed., RN, BC, CRNI

Lynn Hadaway Associates, Inc.

126 Main Street, PO Box 10

Milner, GA 30257


Office Phone 770-358-7861

 Using a 10ml flush on the

 Using a 10ml flush on the distal port wouldn't help any with priming, which is one of the advantages to using a primary/secondary set-up.  We did a small, and by no means scientific study, to see how much fluid is typically lost due to priming and it was about 20cc even when we asked Nurses to be conservative about the amount they waste.  If you're priming using your antibiotic then you could be losing a large portion of the dose to the sink or trash can.

We give a dose of zosyn over 4 hours out of a 50ml bag which means it runs at 12.5ml/hr.  If you infuse until the bag is dry and then just flush from the distal port, you're going to flush about 12.5ml of zosyn, which should have gone in over an hour, not a flush lasting less than a minute.

You're also adding an additional port access with each infusion, potentially increasing infection risk.  

We also using the same primary/secondary setup for all intermittent infusions, something that wouldn't always be possible without the ability to backflush off a primary line.

We consider the secondary to be permanently attached to the primary once it's connected to the primary line.  We try to avoid disconnecting the line from the patient even if it's an intermittent infusion, since it's the disconnecting that makes it "intermittent" by INS definitions.  A line that is continuously connected is considered "continuous" even if it's only infusing intermittently.  

As for "single use" bags, I've never heard it interpreted that way, usually that means it's for one patient and the bag itself can only be accessed once.


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