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SCCM Pod-401 Enteral Nutrition in the Critically Ill

Michael Smith, MD, and Jayshil Patel, MD, discuss the factors associated with managing malnutrition in the critical ill utilizing enteral nutrition and the stages of critical care illness and how it effects nutrition assessment. Dr. Patel explains various considerations for nutrition in critically ill patients including the benefit of early nutrition within the first 24 to 48 hours of intensive care unit admission outlined in the joint American Society for Parenteral and Enteral Nutrition and SCCM nutrition guidelines published in Critical Care Medicine in 2016. Dr. Patel is the associate professor of medicine in the division of pulmonary and critical care medicine at the Medical College of Wisconsin. This podcast is sponsored by Nestlé Health Science.

Published: 11/27/2019

Estimated Time: 23:52 min


Announcer:  This podcast is sponsored by Nestle Health Science, the makers of Peptamen formulas, the only peptide-based formulas with enzymatically hydrolyzed 100% whey protein to help with tube feeding intolerance. Used by healthcare professionals for over 30 years with more than 60 clinical studies. To learn more visit www.peptamen.com.

Michael Smith, MD (Host):  Hello and Welcome to the Society of Critical Care Medicine’s iCriticalCare podcast. I’m your host, Dr. Michael Smith. Today, I will be speaking with Dr. Jayshil Patel. He is the Associate Professor of Medicine in the Division of Pulmonary and Critical Care Medicine at the Medical College of Wisconsin. Dr. Patel, welcome to the show.
Jayshil Patel, MD (Guest):  Thank you very much Dr. Smith. I appreciate the invitation.
Dr. Smith:  Yeah so, we’re going to be talking about the enteral nutrition and how important that is to the critically ill patient today and I kind of wanted to start off with just kind of a general question for you. How important is it to manage the nutrition status of a critically ill patient and is it – and if malnutrition is there; doesn’t that usually comes with some pretty bad outcomes?
Dr. Patel:  Yes, absolutely. Let me answer that question by taking a step backwards for just a moment and try and describe at least from a bird’s eye view of what happens to our patients when they do become critically ill. Critical illness is something that leads to significant substrate utilization. If we think about starvation, for just a moment, if you were to starve yourself starting today; the order of substrate utilization would be glucose, your glycogen stores, fat would get utilized thereafter for ketogenesis but from there, protein is really preserved. The body does everything it can to maintain sort of your lean muscle mass. Now we go into a hypocatabolic state with starvation. Now contrast that to critical illness. Critical illness is a hypercatabolic state. And so, the body does everything it can to ramp up glucose production. It undergoes glycogenolysis which is rapidly exhausted and from there, it’s actually protein that is broken down and the body does what it can to actually limit fat metabolism.
And so, critical illness leads to heightened glucose production and hyperglycemia that’s associated with that. It leads to significant proteolysis and a lot of that protein that gets broken down actually comes from the muscle and the GI tract for example. And so, this is what some have termed the caloric debt that is associated with critical illness. So, the stages of critical illness everything from the early acute phase, late acute phase and the chronic phase contributes to this caloric debt that is associated and we know that the more calories your deficit in critical illness – its associated with bad outcomes. So, it’s another way of saying critical illness certainly predisposes people to an acquired malnutrition state.
Dr. Smith:  Yeah, great description of what’s going on there and then it leads though to another question, right Dr. Patel. In most cases though, isn’t the primary energy source that you are giving to these critically ill patients sugar and not as much protein? Is that starting to change? Are you starting to see in a critical care setting protein supplementation being just as important as sugar?
Dr. Patel:  Yeah, absolutely. I think that we’ve learned a tremendous amount over the past couple of decades. One thing that’s really happened is that survivorship from critical illness is improving. And so as more people survive critical illness; they’re surviving to significant deficiencies in physical abilities. So, they have impaired quality of life simply as a result of what’s happened to them while they were critically ill. So, A, they are sedated. B, they are immobilized. C, they have a heightened inflammation and all of these things sort of combined leads to this proteolysis that we talked about, but we think that that also contributes to the impaired quality of life and physical limitations that these patients can have years after their sentinel illness.
And so now, we think, that by providing these patients greater amounts of protein during critical illness, that we can potentially mitigate some of that. The question still remains though in terms of the timing of protein delivery.
So, the A.S.P.E.N and the Society of Critical Care Medicine 2016 guideline puts forth a recommendation of 1.2 to 2 grams per kilogram of actual body weight protein delivery in all critically ill patients. There are some adjustments for things like obesity for example but in general, 1.2 to 2 grams per kilogram of protein. And there’s significant observational data that’s present now that suggests that that amount of protein or higher may be even more beneficial in those who have again the acquired malnutrition.
Dr. Smith:  Yeah. a couple of questions here. So, first of all, let’s go back to the idea that in the critically ill patient, you are dealing really with a high catabolic state, process that’s going on. You are breaking down the sugar, you are breaking down the protein. Is the goal to reverse that catabolic state or are you just really trying to keep up with it? And are there any studies that show maybe in this case like more protein; will that actually help you to reverse that catabolic state or is it still just kind of keeping up with the loss of the protein and the sugar?
Dr. Patel:  Well I think it’s going to be very difficult to keep up. Now let me again, take one more step back if I may and talk about one other things as we granulate further what happens in critical illness. So, so far, we’ve talked about the significant proteolysis and the loss of amino acids as well. But the other thing that happens at the level of the gut is that there’s significant gut dysfunction. And that gut dysfunction comes in the form of three things. First is that the epithelial barrier is breached. The second thing that happens as a result of that is that the immune system is more favored towards going into a proinflammatory state which perpetuates the inciting inflammation that brought the patient into the critical illness setting to begin with.
And the third thing that happens is our commensal microbiome or the healthy bacteria that live in symbiosis really with us, some may become more virulent as well. And so, the role of nutrition specifically enteral nutrition is in the early phases of critical illness we think, right now, is to support the gut function and so it maintains the epithelial barrier layer which then can perhaps mitigate some of the downstream consequences that I described earlier as well.
At this juncture, if we can partition the phases of critical illness into one of three. There is the early acute phase. This is when people are sick, we are resuscitating these individuals. The late acute phase may be the inflammatory response is starting to wane a little bit where maybe we are starting to remove some of our support systems a little bit and then there’s that chronic phase. Those are the people that are in the ICU typically for more than a week and kind of chug along and have this undulating course if you will.
In that early phase of critically illness, your nutrition in the current era is meant to be delivered to again support the enteral – the gut functions. And we think that you can do that with just a little bit of nutrition. And what do I mean by a little bit? We think we can do it probably achieve it with what is called hypocaloric nutrition. Others have used terms like trophic nutrition as well. And so trophic is just delivering 10 to 30 ccs an hour directly into the gut and we think that that amount at least in animals, preserves the gut barrier functions, the immune functions and such.
Hypocaloric nutrition is also delivering a little bit of nutrition so anywhere from 40 to 60% of the prescribed goal but the difference is that you optimize the protein component of that as well. So, again, in the early hyperacute acute phase of critical illness once resuscitation strategies have been undertaken; we deliver hypocaloric nutrition to support the gut function as best as possible.
Dr. Smith:  And when you do that, when you do that early on, when you support the gut function early on, do you find then that it’s easier to maintain a healthy nutrition status in those later phases? Is there any data that supports that?
Dr. Patel:  that’s a great question. I’m not aware of any data that supports that but here’s what I will tell you. I will tell you that the meta analyses that were cited in the 2016 A.S.P.E.N and SCCM guidelines suggest that if you give individuals early nutrition, so that’s within the first 24 to 48 hours of ICU admission compared to not giving them anything at all through the enteral route; there is improvement in infectious complications as well as mortality as well. So, that’s the one thing that we do know is that data compiled between say 1979 and 2012 suggest that there was an improvement in infectious complications and then data compiled between 1986 and 2011 suggests that early enteral nutrition is associated with improvements in mortality.
Dr. Smith:  Dr. Patel, I want to stick with the protein issue going on here and also the gut. A follow up question to the gut health issue early on. Is anybody looking at some of the healthy gut supplements that might be out there like probiotics early on? Is there anybody looking at that and if so, do we know anything or is there any benefit of adding probiotics early on to the feeding?
Dr. Patel:  There is – there are randomized controlled trials that have delivered probiotics to individuals who are critically ill. However, when they put them into a meta-analysis there wasn’t a benefit that was seen. Now however, I will say, that the largest study of using probiotics was on that was done in a critically ill subset of patients who had acute pancreatitis where they were delivering nutrition right into the small bowel. Many of these patients were hemodynamically unstable at the time and they delivered probiotics again, right into the small bowel. And so one of the criticisms of that particular study is that these individuals were sort of set up for bad things to happen.
When you take somebody who is hemodynamically unstable, and you put nutrition right into the small bowel and you put probiotics right into the small bowel; you are almost going to set them up for failure.
Dr. Smith:  Very interesting. So, let’s go back to the protein. You had mentioned that the average amount and – average is touch with critically ill patients, right but, you said it was around one to one point two grams per kilogram, right and you had said that in some cases there might be some support of using more protein because when I hear that, when I hear one point two and critically ill, that seems kind of low to me. What are your feelings about the average amount of protein that is being used and should we be looking at higher doses?
Dr. Patel:  So, the protein dose that is recommended is 1.2 to 2 grams. Now the lower end of that protein recommendation is based on data that suggests that 1.2 grams per kilogram per day of protein in critically ill patients has be shown to improve nitrogen balance. So, this is what you were referring to earlier when you said that can we keep up with our protein losses. And so, there’s some observational level data that suggests that if you give at least 1.2, you can probably maintain nitrogen balance.
Now, there’s differences in the data. So, for example, one of my colleagues Riley Dickerson out of Tennessee suggested that in a subset of trauma patients; he didn’t get to improvement in nitrogen balance well beyond 2 grams per kilogram per day. So, if you take a general ICU population; 1.2 is probably what it takes to get to nitrogen balance but if you start looking at some subsets, it might actually be even higher. Another subset for example is renal failure.
Dr. Smith:  Well are there Dr. Patel, are there any other comorbidities, obesity, diabetes, that would require maybe a higher protein intake?
Dr. Patel:  Yeah so, the 2016 A.S.P.E.N and SCCM guidelines suggests that in obese patients, so those who have a BMI of more than 30, to actually use more than two grams per kilogram per day of protein but what’s actually emerging in the data and here’s where it gets interesting, is that obviously no two ICU patients are ever alike. And so, what we are doing is we are trying to find subsets of patients who may benefit from more nutrition provision including protein provision and one such subset may be those who are at what’s called nutritional risk. So, nutritional risk is the risk of developing complications from your ICU stay simply as a result of receiving two little nutrition support.
And so, some colleagues out of Canada have developed scoring systems to identify nutritional risk. One such scoring system is called the Nutric score and that score has been applied on day three to say is this patient going to benefit from ramping up the amounts of nutrition? And there’s observational level data that suggests that if you are at high nutritional risk; the more protein you get; there’s an association with improved mortality and they looked at this in individuals who stayed in the ICU for four days as well as 12 days of nutrition therapy.
Dr. Smith:  Wow, that’s pretty interesting. And that’s important to look at some of those lengths of stay too, right, in a critically ill patient it changes the longer that they are in that state and obviously a lot of their nutritional requirements will change as well. Which is also I think makes it hard to study all this, right? You have to really pinpoint what type of critical care patient you are actually looking at, the comorbidities, the length of stay. I want to move on to something different now and talk a little bit about the current guidelines and what they recommend for assessing the nutritional status in a critical care patient. What are some of the things that you look at that helps you to determine if you’re on point with the nutrition or if there is that deficit that you mentioned before?
Dr. Patel:  Yeah, that’s a great question. I will say that the concept of nutritional risk also applies to individual’s health prior to coming to the hospital. So, if you take day zero, you are going to have patients who are admitted to the ICU who come in with preexisting malnutrition. And one tool that many of our dieticians use to identify malnutrition is something called a subjective global assessment. And some of the criteria include things like how much weight have you lost? What’s been your appetite? What’s your appetite been like recently? And depending on what they identify; you can certainly classify somebody as mild, moderate or severe malnutrition. And that’s going to be important. The reason why that’s important is because if you have somebody who comes into the ICU with critical illness and they have preexisting malnutrition; well it turns out that that person might need to achieve a greater protein prescription than somebody who doesn’t. In fact, the recommendations right now for some – for using parenteral nutrition or nutrition through the IV is to start it as soon as possible in those who have preexisting malnutrition.
Because meta analyses have suggested that if you wait and do nothing for those individuals; there’s an increased risk for mortality in that population. So, that’s the first piece is the preexisting malnutrition. That’s the way the SGA is one such way to identify that population as well. But then, there’s people who come in well-nourished or I should really say not malnourished. But the critical illness itself is a risk factor for developing malnutrition. For all the reasons that I mentioned before. Their illness itself leads to again, proteolysis, a hypercatabolic state, some of these patients who say go on dialysis may develop things like micronutrient deficiencies as well. And so, those individuals may also benefit from a greater nutrition provision. But the timing of that is sort of yet to be determined.
The recent European Society of Parenteral Enteral Nutrition or A.S.P.E.N guidelines did a wonderful job by again, partitioning the stages of critical illness. The early acute stage, the late acute stage and the chronic stage and they actually put placeholders in in terms of sort of time, based on time. But the reality is, is we don’t know when patients shift from one stage to another. And that may be important from a nutrition perspective because that might be the time to actually start to ramp up or down their nutrition.
Dr. Smith:  When you are in this process of assessing that, maybe the pre nutrition status and then the status of the patient that you see right there in front of you; how important is laboratory work? Are you guys still looking at say albumen levels?
Dr. Patel:  You know we don’t look at albumen levels. It’s not recommended or pre-albumen levels. I think the data for utilizing pre-albumen levels is for elective surgery patients, outpatients but not in a critical care setting. And the reason for that is because if you were to look at albumen and pre-albumen levels in your critically ill patients on day zero, day one, whatever it is; they are going to be low and they are going to be low because the liver just reprioritizes the proteins it needs to make. So instead of making things like per-albumen and albumen; the priorities are now to make protein for immunity, for wound healing and to combat the inflammation.
Dr. Smith:  Right, right so it just really take – you would expect it to be low and there low and behold it’s low. So, it doesn’t really give you any information to help assess status. Dr. Patel, wow fascinating. We’ve covered so much stuff. We’ve talked about protein, the catabolic state, sugar, the assessment of nutritional status and how important that is. When you look at the specialty and what you do every day; are there areas for improvement in the nutritional status of a critically ill patient?
Dr. Patel:  Oh yeah, absolutely. I guess, how much time do we have, right? But I think there’s sort of many questions that still need to be answered but in the context of what we’ve already talked about; I think we need to better identify how we go from the early stage of critical illness to the late early stage of critical illness to the chronic stage of critical illness. Because that will help us sort of modify our nutrition prescription in many ways. So, for example, right now, as I mentioned earlier the recommendations at least from the A.S.P.E.N guidelines are to do hypocaloric or give a little bit of nutrition through the gut just to support the gut function but one thing we don’t understand very well is how quickly should we ramp that up, right? So, how quickly should we go from say 25% of a caloric prescription up to 100% of the calorie prescription and the reason why that’s going to be important is because there’s certain things that prevent people from ramping it up much, much faster. One of them is like refeeding syndrome. Another one is we know that our critically ill patients have a high endogenous glucose production, or I should really say a variable endogenous glucose production which contributes to the hyperglycemia. Early in the phase of critical illness, there may be more intolerance with greater amounts of nutrition and now, we have data that suggests that there’s mitochondrial failure early in critical illness as well.
And so the substrates we provide, the mitochondria can’t process. So, there’s a lot of work I think that needs to be – to talk about the phases of critical illness when one phase ends, another one starts and what it means for our protein as well as our general energy prescriptions.
Dr. Smith:  Fascinating work Dr. Patel. I want to thank you for the work that you are doing and thank you also for coming on the show today. This concludes another addition of the iCriticalCare podcast. For the iCriticalCare podcast, I’m Dr. Mike Smith. Thanks for listening.
Announcer: Michael A. Smith, MD, received his medical doctorate from the University of Texas, Southwestern Medical Center. He practiced internal medicine and radiology in Dallas, Texas in the early 2000s before transitioning to the pharmaceutical and nutraceutical industries as an educator and consultant.
This podcast is sponsored by Nestle Health Science, the makers of Peptamen formulas. The only peptide-based formulas with enzymatically hydrolyzed 100% whey protein to help with tube feeding intolerance. Used by healthcare professionals for over 30 years with more than 60 clinical studies. To learn more visit www.peptamen.com.
The iCriticalCare Podcast is the copyrighted material of the Society of Critical Care Medicine and all rights are reserved. Statements of fact and opinion expressed in this podcast, are those of authors and participants and do not imply an opinion or endorsement on the part of the Society of Critical Care Medicine, its officers, volunteers, or members or that of the podcast commercial supporter.

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