Infection risk with TPN

[bulgethetwine]

Interesting discussion at our place today. We feed people super early in our ICU. Immediately after big surgeries even, enterally. If they don't tolerate it, we go to TPN as quickly as 48 hours. I was always anti-TPN - the folks that trained me stressed the downsides, the association with one year mortality (which was surely an reflection that the patients getting TPN were the sickies!) and, of course, the problems with TPN as regards the infection risk.

I've always accepted these downsides of TPN at face value. But what isn't clear to me is if TPN REALLY causes any increased infections in the blood stream above and beyond the inherent rate of infection owing to a CVC that is in place?

Could recent advances in measures to reduce line-related infection (bundles, staff training, rigid sterile technique etc.) translate into a lower threshold to start TPN in those who can't tolerate enteral nutrition if there is really no additional risk beyond the line?

Of course, the usual caveat applies - feed enterally where possible. I'm talking about those who can't....

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[bigpharmD]

Interesting discussion at our place today. We feed people super early in our ICU. Immediately after big surgeries even, enterally. If they don't tolerate it, we go to TPN as quickly as 48 hours. I was always anti-TPN - the folks that trained me stressed the downsides, the association with one year mortality (which was surely an reflection that the patients getting TPN were the sickies!) and, of course, the problems with TPN as regards the infection risk.

I've always accepted these downsides of TPN at face value. But what isn't clear to me is if TPN REALLY causes any increased infections in the blood stream above and beyond the inherent rate of infection owing to a CVC that is in place?

Could recent advances in measures to reduce line-related infection (bundles, staff training, rigid sterile technique etc.) translate into a lower threshold to start TPN in those who can't tolerate enteral nutrition if there is really no additional risk beyond the line?

Of course, the usual caveat applies - feed enterally where possible. I'm talking about those who can't....

Patients on tpn have a higher risk for infection than those in the ICU who are not on TPN. Think about it. You are feeding straight sugar into the vein. It is a breeding ground for bacteria. Not too mention patients on lipids have a higher rate of fungal infections. It is not a matter of if they will get an infection it is when.

 

[Tigerz_Fan]

Someone please correct me if I'm wrong:

From what I understand , TPN increases the risk of candidemia. I was also told that the type of lipids that are used in TPN in the US can cause slight immunocompression. And in agreement with above, yes, you are feeding food directly into a patient's veins.

 

[bulgethetwine]

Patients on tpn have a higher risk for infection than those in the ICU who are not on TPN. Think about it. You are feeding straight sugar into the vein. It is a breeding ground for bacteria. Not too mention patients on lipids have a higher rate of fungal infections. It is not a matter of if they will get an infection it is when.

I'm not questioning the theory.

I'm questioning if there is data to back it up. Data controlled for infection owing to the line itself.

 

[SLUser11]

I'm not questioning the theory.

I'm questioning if there is data to back it up. Data controlled for infection owing to the line itself.

Well, it's not just infection that I worry about with TPN. There are plenty of other short and long-term complications of TPN that have to be considered, e.g. ventilation issues, cholestasis, etc.

When it comes to infection risk not related to the line itself, I think it boils down to two main factors: 1. Poorly-controlled hyperglycemia, and 2. bacterial translocation. Obviously you know this, and you're just trying to stimulate some thoughtful discussion….which, by the way, is what is painfully missing from the surgical forums.

Still, at some point, demanding RCTs for everything falls under the "parachute jumping" argument.

I also wonder if you're demand for controlling for CVLs is reasonable, since most TPN studies are in ICU patients, where a large percentage, TPN or not, are going to have central access of some kind. Also, if your ICU patient is for some reason without central access, and you start it specifically to give them TPN at 48 hours, then your argument is irrelevant.

Also, from a cost-containment perspective, enteral nutrition is infinitely less expensive. Although you've specified that we're discussing a scenario when the gut is not an option, you're only waiting 48 hours for that option to arise. While I agree that early nutrition is a great idea, I think starting TPN at 48 hours is a little too aggressive. Next thing you know, we'll be passing dobhoff tubes and PICC lines in the trauma bay or while running codes……..

Now, you could argue that the increased morbidity with TPN is mainly from the increased episodes of hyperglycemia, and not some inherent immunosuppression, I might agree with your point. But then we'd have to start arguing about Van den Berghe vs. the NICE-SUGAR trial, and I don't have the energy for that today…..


I think I get what you're saying overall, though. TPN is not the devil. Still, it's been proven time and time again to be inferior to enteral nutrition, and it carries some inherent risks, so we just have to be judicious with its use.

 

[bulgethetwine]

Well, it's not just infection that I worry about with TPN. There are plenty of other short and long-term complications of TPN that have to be considered, e.g. ventilation issues, cholestasis, etc.

When it comes to infection risk not related to the line itself, I think it boils down to two main factors: 1. Poorly-controlled hyperglycemia, and 2. bacterial translocation. Obviously you know this, and you're just trying to stimulate some thoughtful discussion….which, by the way, is what is painfully missing from the surgical forums.

Still, at some point, demanding RCTs for everything falls under the "parachute jumping" argument.

I also wonder if you're demand for controlling for CVLs is reasonable, since most TPN studies are in ICU patients, where a large percentage, TPN or not, are going to have central access of some kind. Also, if your ICU patient is for some reason without central access, and you start it specifically to give them TPN at 48 hours, then your argument is irrelevant.

Also, from a cost-containment perspective, enteral nutrition is infinitely less expensive. Although you've specified that we're discussing a scenario when the gut is not an option, you're only waiting 48 hours for that option to arise. While I agree that early nutrition is a great idea, I think starting TPN at 48 hours is a little too aggressive. Next thing you know, we'll be passing dobhoff tubes and PICC lines in the trauma bay or while running codes……..

Now, you could argue that the increased morbidity with TPN is mainly from the increased episodes of hyperglycemia, and not some inherent immunosuppression, I might agree with your point. But then we'd have to start arguing about Van den Berghe vs. the NICE-SUGAR trial, and I don't have the energy for that today…..


I think I get what you're saying overall, though. TPN is not the devil. Still, it's been proven time and time again to be inferior to enteral nutrition, and it carries some inherent risks, so we just have to be judicious with its use.

All valid points. I would hate for some of the newbies to think that an argument for forgoing enteral feeding in favor of TPN is afoot here... that would be a big 'no-no'.

I started asking this question exactly BECAUSE nutritionists at our institution are pushing for it sooner and sooner. Almost to the point where they are suggesting we start it simultaneously - i.e. enteral feeding as much as possible to maintain gut integrity (and avoid the aforementioned translocation) but with TPN supplementation to make sure they get their "caloric prescription" (clearly this is an institution where they do not believe in the under-feeding approach, so no point in even bringing that up).

If you were able to do this (i.e. start simultaneously) you would theoretically reduce the risks of TPN to just the infection aspects - which might be due to hyperglycemia, the inherent risk of infection with an additional rate of CVC (debatable in an ICU population) or the inherent risk of infection of TPN itself or some combination of the three.

This is what I am driving it - is TPN an infectious precipitant in and of itself (frequent contamination perhaps? A pro-growth medium perhaps?) or, in theory, if you could still maintain gut integrity with enteral feeding and reduce the risk of infection due to glucose control (agreed: I also don't want to re-hash NICE sugar and van den Berghe data here are the nutritionists on to something (ventilation, cholestasis, etc. not withstanding)?

 

[jdh71]

For me I approach this fairly intuitively. Sick people need calories or they will never get the **** out of my unit. I am VERY interested in these people being on the floor, with that said, I think there is plenty of literature that generally describes more favorable endpoints for patient who reach goal nutrition soonest and stay there. So you attempt the tubefeeds, and to my mind, if this route is either not available given the clinical scenario or the patient fails, then TPN will be the next step and I don't agonize over it. You can argue very persuasively that there is a bias (I forget which one) involved here where the sickest do end up on TPN, and the sickest generally have worse outcomes, where TPN is a correlated factor, but to my mind a very difficult factor to call causative based upon what I've seen (and I admit while I try to read a lot, I obviously have not read everything)