TPN and anesthesia

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As a pharmacist, I'd rather you dc the tpn & run d10. The tpn solutions are very complicated chemically & if you need that port for any reason at all, I'd rather you not mess up my solution which costs about $450 & we bill to the pt about $1000 (this varies if your facility is using a once a day solution or by the liter). The drugs you put thru your lines will cause precipitation of the tpn components which you may or may not be able to see or cause the emulison to break. At the least, if you need that port, you'll just toss it anyway...

If the tpn got tossed, left, whatever & your pt gets to icu or pacu & we are short a liter, bag, etc.. & there are orders to "continue tpn" then we have to remix a solution which can occur late in the day/evening. tpn solutions are made by midday, usually after the early am labs are read & we don't have as much staff in the evening. In these situations, the nurses are used to hanging d10 until we can get it made.

Your pt can do without the amino acids & lipids for as long as you need without any issue - we do this on medical floors routinely.

Thats just from my perspective though - selfish !

sdn1977 said:

Thats just from my perspective though - selfish !

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Good to know though especially the price!

apma77 said:

other than cost, is there any other reason to change to d10?

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yes - hyperkalemia & hypoglycemia which is due to too much insulin in the bag. That is the only time we will have a bag removed & remade. All other changes can be done peripherally & incorporated into the next day's solution.

As I posted before....if your clinical situation becomes so acute you need to use the tpn port in addition to all the other lines you may have started, please take the tpn down. If you put a drug thru that line, you'll change the osmolarity, osmolality & pH such that the components will precipitate out in the line itself where you can't see it. Also...the tpn solution is like a liquid agar plate - a terrific culture media. In these situations, we'd rather you take down the tpn, hang d10 & add push drugs without the complication of such a complex bag of chemicals.

I run tpn at less than 1/2...and check glucose in the OR...why....I don't know.

When I was a medicine intern, we were told that if we stopped the TPN infusion, or disconnected the tubing, we had to waste that bag. I don't know if that was a hospital specific thing or what, but that's stuck with me. Given the expense, I usually try to keep it going and check sugars or blood gases which give me the sugars and key electrolytes.

The thing I find ironic is when people stop TPN because the patient is NPO for surgery.

bubalus said:

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The thing I find ironic is when people stop TPN because the patient is NPO for surgery.

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What! NPO means nothing by mouth. I would not be able to keep from laughing in there face.

I was always told that you should continue running TPN through the case, and frequently check sugars. The TPN always remains on a dedicated line.

The hospital policy should follow the standard of practice. That is....

- the tpn line is dedicated to just tpn & is the lowest port on a triple (or double) lumen catheter. That means...no other drugs, fluids (excluding lipids - there is always an exception ), lab draws, etc.

- however.....when the #*%$ hits the fan, which can sometimes happen - you might need that port. No problem - just remove the tpn & use it. The possible contamination can be dealt with later - running d10 until you know there is no source of infection or just putting in a new line on the other side. When push comes to shove....money is just that! I have been known to throw away a tpn because I felt I contaminated it when I mixed it. I know its a lot of money, but the money which might have been spent on a nosocomial infection is far greater than the money I threw away!

- NEVER add anything to the tpn bag! It is a complicated mix of chemicals & pH, osmolarity & osmolality dependent. If you add something, either your new drug may precipitate out or one of the components of the tpn will. The precipitates can be flocculantly white or a clear crystal which is difficult to see in the line & you can't see in the lumen of the catheter.

- nothing should hang longer than 24 hrs - tpn, d10 or lipids - no matter the amount remaining (which could be quite a bit if you run it 1/2 speed like mil), it has to be changed every 24 hrs, no matter what!. The tpn is a tremendous growth media (exponential times larger than d5).

- the tpn can be interrupted & restarted without discarding the bag. The standard of care, however, is that if it can be documented there is no one who has contaminated the line or port, it can be stopped & restarted. This happens with MRI's, etc..when the radiologist doesn't want it running. An rn goes with, disconnects, hangs d10 & stays with a d50 syringe & reconnects when the pt is done. However, if you're an intern, you wouldn't have than continuity, so the bag gets discarded. If we know about it, the test is timed to the pt & we might wean the drip so the bag runs out about the time the test is done.

- the only thing complicated about tpn is the dextrose, k & insulin. The dextrose is 20-25% - watch the bs. The continuous infusion of such a high concentration of dextrose has overridden the normal insulin secretion mechanisms & the insulin in the bag is short acting, so you won't see a "normal" response to a bs drop. It takes much longer for the pancrease to kick back in which is why tpn is titrated down over a day when it is stopped,or the bs is followed closely. Also, when you see those insulin units on the label - some of that has adhered to the plasticizers, so the pt never is actually getting that amt....it has been titrated to effect. The sodium is usually never greater than that in ns. The k can be high or at zero - depending on the pt. If your k level is too high, & you have k in the bag, you just have to pull the bag - you can't get it out. If its too low, add it to another of the central ports - not the tpn. If you send a pt out to the ICU this unstable...we won't put k or insulin in the tpn - it will be added to a separate IV (or added at a very low level - 10mEq/24hr or 5 units/24hrs) for 24-48hrs to stabilize then added back in. This makes the nurses upset, but it decreases our costs.

- if its a 3-in-1 tpn - with the lipid mixed in....you can't use regular tubing - you have to use the tpn tubing that comes with it. In a pinch, you can use propofol tubing. The lipid leaches plasticizers.

- anything beyond this is hospital policy - not necessarily standard of care & governed by other influences - economics & politics for example.

...Propofol tubing?

Gator05 said:

...Propofol tubing?

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Yep - DEHP free tubing. Probably not used so much in the OR, but common when a continuous propofol drip is used in the ICU & very, very common in the PICU or NICU.

You may not see so many 3-in-1 tpns anyway to make this of any significance anyway.

Hey sdn,
Why is TPN so expensive? It sounds like you're saying the actual materials are expensive, not just the expertise and time needed to make it. Do you know why?

Mapleson D said:

Hey sdn,
Why is TPN so expensive? It sounds like you're saying the actual materials are expensive, not just the expertise and time needed to make it. Do you know why?

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Mostly its the labor which is so expensive. The major monetary component is the lipid (if its a 3-in-1) or the amino acid, but this can be a hidden cost since these costs are usually bundled into the the fluid contract the hospital has.

For example...you may be an "Abbott" hospital - all your fluids come from Abbott, so your amino acids will probably be Aminosyn, you lipids will be Liposyn, your pumps & your tubings will be from Abbott. Everything is bundled together.

A hospital cannot charge for the pump - that is like the bed & the nurse - it comes with the room - it doesn't matter how many pumps or nurses the patient uses. BUT......the hospital charges for the tubings & the solutions & the connections, etc... & they charge a lot!

The pumps are re-evaluated & changed about every year or so. Which means new inservices to nurses - all at the expense of the company providing the pumps - which is recouped in the charges they make on the "disposables". So - its hard to tell you how much each hospital pays for amino acids & lipids - its so dependent on the total usage. Dextrose is cheap - $1/liter - the charge to the pt however is probably $20 - its all "funny money".

Each individual component - kcl, nacl, mgso4, ca gluconate, mvi, trace elements, etc....each of these is about $10 - not so much.

Now...specifically, for a tpn - there are on average about 12 different ingredients in each tpn. If we are making a 3-in-1, the order of mixing is tricky to not make the suspension "crack" or separate. If we are making 3 liters a day....it is many, many manipulations, which require tremendous aseptic technic by the tecnician & careful checking by the pharmacist. Only one can be done at a time, contrary to cefazolin bags or syringes which can be made 20-30 at a time. Once that bag gets to the floor, each component of the tpn must be checked by the rn that hangs it - again - time consuming. The pts insurance does not pay for that rn - it pays for a diagnosis & supplies used......so...the cost of the tubing, tpn, etc...incorporates my time & expertise, the rnss time, the techs time who made it, etc....

If we inadvertantly introduce a bacteria (which I have unfortunately been the source of a nosocomial infection traced to a tpn mixture I made to my everlasting regret!!!!!) it is going into a tremendous source of nutrient for that bacteria - 20-25% dextrose - even better than an agar plate.

So....we take a culture after each tpn has been made to check our technique. That adds to the expense.

From the time I receive a new tpn order.....for me to review it, check the labs, write the compounding order & have the bag be mixed - it could take 2 hours or more, depending on how busy we are at the time. Each day, the orders are check against the am labwork. If we are not actually writing the orders ourselves.....we make sure the physician has seen the labwork & has decided not to make any changes before we proceed. That in itself can be time consuming, particularly with surgeons (we often use their PAs for this!)

If there is anything which appears to be a trend over time (rising k+ for example over the previous 12 hours).....we might suggest withholding the k+ from the tpn bag until the physiologic issue stabilizes which is causing that change then add it back in gradually.

Nothing is ever - EVER added to a tpn bag once its been hung on a pt. All changes are made peripherally until they are stable & then we add slowly. There is a pharmacist who follows this so we don't waste both our time & our resources.

So.....mostly its labor. Hopsital billing in a nutshell.

SDN,

As typical of you, awesome input.

Yes, thanks for the great explanation.