Choosing the right protein bag when prescribing TPN

Choosing the right protein bag when prescribing parenteral nutrition to your patients.

I would like to discuss with you the stress response of how it specifically impacts the protein metabolism. And then we’ll look at to nutritional management how much protein, when to give and just lastly, discussing some practical applications.

Stress response

The body responds to stress, and injury is an orchestrated response. By ever, the intensity of the stress response and the duration of the stress response have massive implications for nutritional status. Two of these nutrients that we need to take into consideration when we plan on nutritional scripts are how the body responds in terms of glucose and protein.

Two with the massive mobilization of substrate in order to match the energy expenditure through the process of gluconeogenesis, hyperglycemia results. Protein is mobilized in order to provide amino acids to feed into the gluconeogenesis. Also, to provide amino acids for acute phase protein production. But this unfortunately results in a loss of muscle mass.

Recent studies for TPN during ICU admission

If we look at the recent studies, literally a fifth of muscle mass being lost within the first 10 days of ICU stay. What are the consequences or the impact of that loss of muscle mass?

This systematic review looked at muscle loss, sarcopenia perioperatively. And they look at what would be the effect on it postoperatively in terms of major complications, and they found a 40% increased risk for major complications in those with muscle loss going into the procedure.

Impact on mortality

Also, we know that a low muscle area significantly impacts on mortality, where those with sarcopenia have a significantly higher mortality rate. So how can we manage that through our nutritional prescription? And again, we’re talking specifically about protein.

Mortality reduction with TPN

I’m going to share with you results of three studies. The first one the study by zusman looked at the best mortality reduction in protein intake. And they found that once you pass 75% of the target in their case, the target was set at 1.3 grams per kg per day exceeding 75% resulted in a reduction in mortality. The second study by Peter JM Weijs and his colleagues have indicated a 1.2 grams per kg target, but specifically also added the day. So, by day four, you need to reach at least 1.2 gram to have a mortality reduction.

Interestingly, in the study by Weijs, that this mortality reduction was only found in the non-septic patients. So, the protective effect of high protein was lost in those with sepsis.

The third study that I want to mention by Koekkoekk et al, have found that it’s not just the amount of protein but also the timing component. And they recommend a progressive time dependent increase in protein, starting slowly and gradually building up in terms of the amount that you consume.

Gradual escalation is key

So, these considerations were taken into effect when the ICU guidelines from espen as well as from other colleagues working extensively in this field, and then made their recommendations.

Gradual progress of intake of protein is recommended.

If we put that into consideration with an energy recommendation, just because the two obviously go together, you will see that for the early acute phase, we recommend protein less than 70% of the X energy expenditure and protein in the region of 0.6 to 1.2 grams per kg bodyweight. Moving into the next three to four days, we recommend energy between 80 and 100% of target, preferably measured through indirect calorimetry and protein 1.3 to 1.5 grams per kg. And moving beyond the first week in the ICU, we can start to increase the energy and the protein even more.

So, what are the practical challenges when we want to apply these recommendations? I think for us most importantly, balanced nutrition at all points in time, we should ensure that we tick all the boxes for all the nutrients.

But it’s not always that easy. I’ve already mentioned to you that during the acute phase, and especially when the stress response of the body is in there, and then active phase, there is a high production of energy. So, through the process of autophagy, the body can literally produce up to 1500 kilocalories per day.

So, for energy in the beginning, start slowly, provide hypo-caloric feeding and gradually increase.

TPN, proteins, carbs and fats

Protein in the beginning stages is most likely guided by the energy content. If you have a restricted energy content, you will struggle to meet your protein requirements. Another challenge, which I believe is not yet sorted out, is whether we should use total protein or protein equivalents. You will note that the Espen guidelines state for protein 1.3 grams per kg protein equivalents. That means for every 100 grams of a mixture of amino acids, we actually only end up with 83 grams of total protein. And that will make a huge effect on how we calculate our requirements.

For carbohydrates and fats. Probably the most important thing that I want to highlight here is the use of non-nutritional energy sources, be aware of that, if the protein is receiving the glucose containing IV infusion, that will have major implications on total caloric intake, as well as carbohydrate intake.

If the patient is being sedated, for instance, getting propofol, again, it will affect calories as well as fat, we have to take that into consideration when calculating our requirements.

Micronutrients to TPN

Micronutrients demands to be added to all prescriptions, whether it’s enteral, whether it’s parenteral, because we have to ensure a balanced intake. So, make sure that you add the required ampules of the individual micronutrients at complementation levels.

Complementation levels mean basal levels of intake. And also remember that when they are abnormalities in the micronutrients that you have to manipulate your script.

Fluid restriction or not!

For fluid, if we have the luxury of no fluid restriction, you can pretty much choose any product as long as it meets the requirements, or ever if you’ve got fluid restriction, it has a major impact on choice of product. Therefore, know the available products, know the nutritional composition of the products and choose the product that matches your requirements best.

It’s also a good practice every day on the on the ward round to decide on the target nutrient or target nutrients for the day. Because you might not always be able to tick all the boxes, but you need to know which nutrients are you going to chase for that day, if possible, chase protein?

Case study – Practical application

So lastly, just a quick case study that I want to discuss with you. This is a 51-year-old male admitted with severe abdominal trauma, multiple small bowel perforations. He had some damage repair, clip and drop, and he ended up with an open abdomen admitted to the ICU. The body mass index of this patient was 36. And we calculated his adapted weight at 75 kgs. By day three, even though he was still getting some inotropes, he was hemodynamically stable. We could start with a low dose TPN.

By day 4, inotropes were stopped, TPN could increase, and we were lucky that we were able to perform indirect calorimetry on the patient. And what we found was an IC value of 1799, so basically 1800 calories.

By day 4, we should aim for 80% of the energy expenditure. So, 80% of the 1800 it’s about 1400 calories, protein day four to 1.3 grams per kg, so it’s about 98 grams. I’ve also calculated the glucose oxidation rate and the fat requirements 0.7 to 1.5 grams per kg. And just a reminder, micronutrients complementation levels. So, if we have to choose a PN bag, that will best match these requirements.

If we prescribe one liter of Triomel/Olimel N9 840E. And we also add to that another liter of Triomel/Olimel N9 840E, but only the protein component, we will be able to match the protein perfectly. Energy will be slightly below. Obviously, the carbohydrates and fats will be lower because we’re not yet at 100% of requirements. If you’re worried about the energy, you can always again at this case, use a non-nutritional energy source to your advantage. Use a 5% dextrose one liter solution, which will add another 200 calories. And then again, you can tick the box for calories. Remember to add your ampule of water-soluble fat-soluble vitamins as well as trace elements.

So, by day 7, we repeated the indirect calorimetry, and we got a value of 2214. We know that we can use 100% of the energy expenditure. That means 2200 of protein should be 1.5 grams per kg, which comes to about 113 grams. Carbs, fat, and micronutrients remain the same.

So, my recommendation is that we now use a Triomel bag two liters of N9 840E, that will meet the requirements for our energy, for our protein, for our carbohydrates, and for fat.

Or ever if we choose another bag, if we choose the Triomel/Olimel N7 960E, same volume, but different protein component, we will tick the box for energy for carbohydrate and for fat, but for protein we will have significantly less. It’s basically 1.2 grams per kg.

Take-home note

So, this shows the importance of choosing the volume wise the bag that provides you with the most protein or the most nitrogen. So, nutrition prescription should be adapted according to patient’s needs. According to the clinical condition. We should administer the right amount of nutrition, in this case protein, or choosing the right product, and we should administer it at the right time progressively increasing and I’m sure that you will agree with me. That personalized nutrition approach is absolutely vital.

References

• Zusman, O., Theilla, M., Cohen, J. et al. Resting energy expenditure, calorie and protein consumption in critically ill patients: a retrospective cohort study. Crit Care 20, 367 (2016). https://doi.org/10.1186/s13054-016-1538-4
• Weijs, P.J., Looijaard, W.G., Beishuizen, A. et al. Early high protein intake is associated with low mortality and energy overfeeding with high mortality in non-septic mechanically ventilated critically ill patients. Crit Care 18, 701 (2014). https://doi.org/10.1186/s13054-014-0701-z
• Koekkoek WACK, van Setten CHC, Olthof LE, Kars JCNH, van Zanten ARH. Timing of PROTein INtake and clinical outcomes of adult critically ill patients on prolonged mechanical VENTilation: The PROTINVENT retrospective study. Clin Nutr. 2019 Apr;38(2):883-890. doi: 10.1016/j.clnu.2018.02.012. Epub 2018 Feb 17. PMID: 29486907.