Secondary IV infusions

[eiwneon]

I'm a new nurse, and I have a couple questions about running secondary IV infusions:

When I hang a medication to be given via piggyback infusion, I usually use my IV pump to backprime the secondary tubing first, and then start the piggyback medication. This is the way I was taught. And it's also the way I was taught to back flush in between two different secondary medications. Anyway, I've noticed that some people also do this, but others prime the secondary tubing with the medication itself, then attach the secondary tubing to the secondary port on the pump cassette and start the pump. Thoughts?

The other part of my question has to do with VTBI. I always program my VTBI as exactly the amount that is in the secondary piggyback medication bag. But now I'm wondering, does the fact that I primed the secondary tubing with primary fluid mean that I'm not giving the patient the entire dose of medication? I assume that for the first few minutes of the secondary infusion, the patient is just receiving the fluid that was primed into the tubing. Even if I were to prime the secondary tubing with medication like some nurses do, the bottom half of the IV tubing that is common for the primary and secondary lines is filled with primary fluid and that's still what the patient is getting for the first few minutes. Not sure how much the tubing holds I will have to check the packaging but still. Do you see my confusion? So I'm wondering how you approach that.

If you're still with me.... I imagine there would be some residual in the secondary bag still. And the last part of my question goes off of that - I'm worried now that I might be always undermedicating my patients, because isn't there always residual secondary fluid? ie there is always some fluid left, if not in the minibag itself at least in the secondary line ie we don't run it dry. by this logic should we really be flushing the secondary line? but I've never heard of this...

One more thing. I see "overfill" listed on the label of some IV medications prepared by pharmacy. like the label will say 117 mL plus overfill. What do you program then? What's the rationale? How much overfill?? And therefore what do you set as the VTBI?

Not sure where to look for answers. Thanks for helping me think through this.

[Wuzzie]

I honestly think that little extra or less would cause little harm to the patient to get either

I think that would be patient and med dependent. For instance a 20ml overfill of a 100mg/50ml is 40mg extra if everything is infused. That's nearly half again as much as the ordered dose. I wouldn't want to give that. Nor would I want to undermedicate. But don't forget a good chunk of my experience is pediatrics and oncology where the margins for error are much smaller. And before it's mentioned the 100mg/50ml is just a random figure I chose so yes it's an unlikely dose for a pedi patient.

[JKL33]

This is an interesting document.

We should inquire w/ pharmacists in our own institutions probably (?)

[Wuzzie]

This is an interesting document.

We should inquire w/ pharmacists in our own institutions probably (?)

Yes, that is what i found when I was looking.

Here's another

Understanding and Managing Intravenous Container Overfill

[Wuzzie]

This is actually an excellent discussion and I'm betting everyone who reads or participated in it is going to look more closely at their piggyback bags.

Here's a mind blower for you younglings. When I started there weren't commercially prepared IV solutions. We had to mix them ourselves and I worked in the NICU. No hood, no pharmacist. Just the recipe book and vials of saline and potassium. Yikes!

[JadedCPN, BSN, RN]

The secondary tubing should be primed with the primary fluid, using the secondary medication to prime the tubing sort of misses the point of using a primary/secondary set up. This is particularly true of infusions after the initial set up, since then you would be disconnecting the secondary from the primary to prime the secondary tubing, which adds an unnecessary opening of an otherwise closed system.

Keep in mind that in a true primary/secondary set up the secondary volume you set the pump for doesn't mean the pump will only infuse from the secondary bag for that set volume, really you're just telling the pump to run at one rate for a certain volume, and then switch back to the primary rate. So if you set the secondary volume for 100ml but there are 120ml in the bag, and the secondary rate is 200 and the primary rate is 25, then the first 100ml of the secondary will infuse at 200ml/hr but the last 20 ml will take almost an hour to go in since the pump will switch back to the primary rate of 25.

The amount of residual medication depends on the height difference between the primary and secondary. What you're doing with a primary/secondary setup is creating a single fluid column with the secondary bag and usually at least part of the tubing above the top of the primary fluid. So long as the secondary bag is sufficiently above the primary, there will be minimal residual. If you really want to get it all in except for a miniscule amount, then you could backflush the secondary bag and allow that to infuse.

This is how we do piggybacks in my facility.

[RNrhythm, BSN, RN]

The bag the secondary tubing comes in will tell you the volume of the line. I think mine are 8 mL, so I backprime and then add 8 to the VTBI.

[smf0903]

I work nights and we don't have pharmacy in house during night shift so we mix a lot of our meds. The only thing we can't mix is potassium. Some things have mini bags that we can attach the vial right to and mix, some things we actually mix.

I always backprime. I always add extra to the VTBI so that it all goes in, including what's in the line. My secondary lines are dry when it switches over to the primary. For things like vanco, I always go back when the infusion should be done and check to make sure I don't need to program more.

If the patient is getting a Q6hr infusion, leaving even a little in the bag adds up over the course of the day.

I only have multiple secondary sets if I have multiple infusions running at the same time. Otherwise everything gets back flushed and whatever I need to hang gets hung from that secondary set. I can't imagine having one secondary set for every different type of med, that seems like such a waste of tubing and money.

ETA: we use alaris pumps :)

[mtmkjr, BSN]

I don't see a logical reason to back prime the secondary line with primary fluid unless it is for compatibility purposes when the secondary line is used for more than one med.

The quote below is from our hospital P&P (we use Lippincott)

I need to investigate a little further, because our unit does not do the programmed bolus at the end as it is written...

I find it interesting that there is so much variation in such a simple procedure. The inconsistency in administration leads to patients sometimes receiving significantly more or less than what is ordered.

Secondary Set

a. Set up a primary infusion of NS 250mL if no maintenance IV fluid ordered.

b. Remove hanger from secondary package.

c. Hang primary container on the fully-extended hanger.

d. Close on/off clamp on secondary set, spike secondary medication container, and

hang container higher than the primary container.

e. Squeeze and fill drip chamber to the fill line.

f. Open On/Off clamp to obtain flow and prime the line.

g. Close roller clamp.

h. Cleanse the primary set (upper y-site) and attach the secondary set.

i. Open roller clamp and program pump to infuse the secondary medication.

j. Check flow for drops falling in the secondary not the primary drip chamber.

k. Use clamp to occlude flow from primary bag.

l. After secondary infusion is complete, program a flush of the NS primary fluid of

20mLs. Select the BOLUS soft key and enter required data for delivery of 20mLs

NS. Remain with patient until flush is complete. Exception: Certain IV

medications require infusing the bolus at the same rate as the medication was

infused. These medications will be designated in the Smart Pump with a clinical

advisory that reads "Follow infusion with NS flush programmed at the same rate

as the infusion". For drugs which are not compatible with NS, use 250mL D5W

for the flush (ex. Amphotericin, Synercid).

m. Discontinue tubing from patient's IV and apply cap to tubing.

[Alex_RN, BSN]

So is it a safe bet to assume that a pre-prepared IV bag should be run until emptied if the label and dosage are the same volume? For example, a 250mL bag of Vanco should be run until empty even though the pump, programmed for 250 mL, stops with significant visual volume in the bag, like 20 mL?

[MunoRN, RN]

Hmmmm. Never done it that way. We have separate tubing for each med. Okay then, but if you set the pump to infuse the left over medication then aren't you actually giving a bigger dose than ordered? Most bags have at least 20ml of overfill.

The overfill is in volume, not medication. A medication prepared in a 100ml bag with have overfill from two sources; the manufacturer overfills the fluid, typically about 5-10mls but it varies by the bag size and manufacturer, and then there will be the volume of the medication added (10ml of 500mg Ancef added to a 105ml bag for instance), but the overfill does not involve extra medication. A 500mg bag of Ancef will still only have 500mg of Ancef regardless of the overfill, so while it may have 120ml of fluid in it, it's still 500mg in the whole bag, which means the whole bag needs to be infused to give the ordered dose.

[MunoRN, RN]

Why would you prime the secondary tubing with the maintenance fluid? Prime it with the secondary fluid when it's first hung and when it's done infusing it will be pre-primed for the next dose so you don't have to break into the system. Also, just curious about what pumps you are using? I'm having a difficult time picturing how your pumps work. I have not experienced pumps running the way you are describing.

Priming the secondary tubing with the secondary medication instead of backpriming from the primary bag has the potential to waste the secondary medication resulting in underdosing, but also for subsequent secondary infusions this would result in the secondary tubing being manipulated for no reason, once the secondary tubing is attached it should be considered permanently attached, flushing the line between medications can be done by backflushing (hold the empty bag from the previous secondary infusion below the level of the primary bag, this will flush primary fluid through the tubing and into the old secondary bag, flush sufficiently to prepare the tubing for the next med, then toss the previous bag). The same technique can be used for first dose to prime the secondary tubing using the primary fluid.

I've used Sigmas at the last two places I've worked.

[BlueShoes12, BSN, RN]

Priming the secondary tubing with the secondary medication instead of backpriming from the primary bag has the potential to waste the secondary medication resulting in underdosing, but also for subsequent secondary infusions this would result in the secondary tubing being manipulated for no reason, once the secondary tubing is attached it should be considered permanently attached, flushing the line between medications can be done by backflushing (hold the empty bag from the previous secondary infusion below the level of the primary bag, this will flush primary fluid through the tubing and into the old secondary bag, flush sufficiently to prepare the tubing for the next med, then toss the previous bag). The same technique can be used for first dose to prime the secondary tubing using the primary fluid.

I've used Sigmas at the last two places I've worked.

This is exactly what I do and how I was taught in nursing school, except for the fact that we use Alaris pumps.