“Parenteral Nutrition Indications and Practical Applications”  by Katelyn Ariagno for OPENPediatrics

“Parenteral Nutrition Indications and Practical Applications” by Katelyn Ariagno for OPENPediatrics

Parenteral Nutrition: Indications and Practical
Applications, by Katelyn Ariagno. Hi, my name is Katelyn Ariagno. And I’m a Registered Dietitian here at Children’s
Hospital Boston. Today, we’ll be talking about a couple different
nutrition topics specific to the ICU and ICU care. Just to remind you that these are guidelines
that we’ve established here at Children’s Hospital Boston, and you may need to alter
these guidelines depending on your institution and your resources that are available to you. Nutrition Assessment and Estimating Nutrition
Needs. The first topic I’ll be talking about today
is estimating nutritional needs. Estimating nutritional needs in the critically
ill child remains a challenge. Anthropometric data such as weight, height,
or length are not always easily obtainable in the ICU, and they’re not always accurate
due to other compounding factors in the ICU. Additional anthropometric data, if able to
be obtained by a skilled clinician, include triceps skinfold measurements, or mid-arm
circumference measurements, which can better assess the patient’s baseline body composition,
such as their total body fat, or their degree of malnutrition. Along with anthropometric data, the physical
exam of a patient plays a crucial role in better assessing a patient’s clinical baseline
nutritional status. Noting whether a patient is edematous, has
any temporal or muscle wasting, or altered skin integrity may further influence your
final goal energy and protein needs. Weight changes over time, in addition to trends
and anthropometric data, remain the gold standard in determining if your energy goals are accurate. This is why it is important to obtain these
anthropometric measurements on a regular basis. Just as a patient’s clinical status changes
in the ICU, so do their energy demands. Nutritional Needs of Critically Ill Children
versus Healthy Children. The nutritional needs of critically ill children
significantly differ compared to healthy children. More research here at Children’s has shown
that the energy demands of a critically ill child are significantly reduced. Factors that are contributing to this include
patients being on bed rest, they’re commonly on sedation medications and chemical paralysis,
along with being on mechanical ventilatory support, which significantly reduces their
energy demands. Also if a patient is receiving parenteral
nutrition support, it is thought that the thermic effect of food is reduced by about
10% because the body is not using any energy to digest and absorb the macro-nutrients. If energy needs are incorrectly assessed a
patient becomes at risk for being underfed or overfed which can further complicate a
patient’s clinical condition, such as length of stay in the ICU, days on mechanical vent
support, or they also may become at increased risk for infections. Based on these metabolic factors playing a
role in a patients energy demands, here at Children’s we estimate a resting energy expenditure,
or REE, using the equations WHO or Schofield. We then use a stress factor that we multiply
to result in a number that we call total energy expenditure. The stress factor that we commonly use here
ranges from 1 to 1.3, but can be as high as 2 if a patient is a status post to trauma
or thermal injury, as well as if a patient needs to undergo nutrition rehab, such as
catch-up growth. Point of clarification, depending on the individual
patient, a stress factor may not always need to be applied when estimating energy needs. Patients may also have changing energy needs
during different stages of their illness. The RDA and DRI equations overestimate energy
needs in a critically ill child, therefore, are rarely used here at the hospital in the
ICU setting. Indirect Calorimetry remains the gold standard
when attempting to assess Basal energy needs and should be considered for a patient that
is undergoing metabolic derangements in the ICU. Indications for Parenteral Nutrition. Next I will be talking about parenteral nutrition
support, or here at Children’s the abbreviated version called PN. It is important to first identify the appropriate
circumstances when PN should be used as a primary form of nutrition support. Generally, this includes patients that are
on bowel rest, have altered bowel function related to medical or surgical conditions,
and anticipate being unable to be enterally fed for greater than five or more days. For infants, or severely malnourished patients,
our threshold to starting PN is closer to three days. Once PN is deemed appropriate, we then identify
the IV access the patient has. This will determine the PN solution you are
able to infuse. Preferably here at Children’s, the tip of
the central venous line should be in a large vessel, such as the right atrium or the superior
vena cava, where the venous flow is at its maximum and can handle a concentrated solution. If a patient only has peripheral IV access,
the challenge becomes meeting their energy needs because the concentration is limited
to not exceed 900 mOsm per liter, which usually correlates to a PN solution of a dextrose
of 10% and a 2% amino acid solution with standard additives. The next step in initiating PN is reviewing
the patient’s fluid status and electrolyte trends. Here at Children’s Hospital Boston, we estimate
fluid requirements using the Holiday-Segar Method. As a patient is initiating on PN and being
maintained on PN, monitoring hydration status closely is very important as fluid needs may
change, depending on a patient’s clinical condition. A patient may require increased fluids if
they have insensible losses such as being persistently febrile or if they have increased
losses via stool or nasogastric tubes. Also, a patient may require a concentrated
fluid for their PN if they are becoming fluid overloaded. Here at Children’s, our PN solution is a two
in one, where our lipids are infused separately. We also dose our contents of our PN per liter. Our three macronutrients included in our PN
solution consists of carbohydrate, being dextrose with a 3.4 calorie per gram, proteins, which
is a crystalline amino acid, which is 4 calories per gram, and fat, which is a soybean safflower
emulsion, which is a 20% solution, 2 calories per milliliter. In terms of dextrose, we look at it as being
our primary source of calories in our PN. And we use a glucose infusion rate or GIR
as our measurement to help initiate and advance the PN solution. It is recommended here of starting a glucose
infusion rate of around 5 milligrams per kilogram body weight per minute. We then will advance the GIR by a range of
2 to 5 milligrams per kilogram per minute, which equals a 5% to 10% dextrose increase. The upper limit for the GIR varies depending
on age. For infants, the upper limit for the glucose
infusion rate is anywhere from 10 to 14 milligrams per kilogram per minute. For children ages 1 to 10 we do not like to
exceed a GIR of greater than 10. And for adolescents we do not like to exceed
a GIR of greater than 6. When advancing the GIR and PN, we closely
monitor blood sugar levels, as well as urine lights, making sure that there is no glucose
noted in the urine. In terms of protein, we do not like to use
it as a primary fuel source as we do with carbohydrates, but instead dose it appropriately
to prevent further loss of lean body mass. Our protein, our crystalline amino acids,
contains a combination of essential, semi-essential, and non-essential amino acids with the combinations
varying depending on the age of the patient. For infants we use the solution TrophAmine
and for children greater than the age of one, we use the solution Aminosyn. In terms of initiating the protein in the
PN, for infants we initiate protein at 2 grams per kilogram body weight, and for children
and adolescents we initiate protein at 1 gram per kilogram body weight. With advancement we increase protein by 1
gram per kilogram body weight every day to our desirable upper ranges. For infants the upper range of protein is
3 to 4 grams per kilogram body weight per day. For children our range of protein is 1.5 to
2.5 grams per kilogram per day. And for adolescents our range is 1 to 1.5
grams per kilogram per day. It is also important to take note though the
instances where children will require more or less protein outside of these ranges. Such as a patient that is status post-trauma
or with open wounds requiring increased protein, or if a patient is showing signs of developing
renal failure requiring less protein. We however, do not like to go lower than the
RDA for protein to again, prevent further lean body mass loss. With our fat source being a 20% solution called
Intralipid, it contains a combination primarily more of omega 6 fatty acids to prevent essential
fatty acid deficiency. We initiate the lipids for all ages here at
Children’s at 1 gram per kilogram per day. And we’ll advance by 1 gram per kilogram to
again, our desirable upper ranges based on the patient’s age. For infants, our upper limit for lipid dosing
is no higher than 3 grams per kilogram per day. For children ages 1 to 10 it’s a range of
1.5 to 2.5 grams per kilogram per day. And for adolescents we do not like to exceed
a dose of 1.5 grams per kilogram per day. We recommend prior to initiating lipids obtaining
a fasting triglyceride level to ensure optimal tolerance. And depending on the dosing of the lipid and
the length of time they are on PN, we also like to monitor essential fatty acid panels. The next component of our PN solution consists
of our electrolytes and additives. The standard electrolytes we include in our
PN solution here at Children’s includes sodium, potassium, phosphorus, chloride, magnesium,
and calcium. Our sodium standard ranges from 2 to 4 milliequivalents
per kilogram, and our potassium and chloride ranges from 2 to 3 milliequivalents per kilogram
body weight. We strongly recommend correcting any electrolyte
derangements prior to the initiation of PN, as it is very difficult to manage electrolyte
shifts once the PN is infusing. And any acute changes in PN rate or volume
can adversely affect macronutrient metabolism, such as hypoglycemia or hyperglycemia. Patients again, may require additional or
less additives in electrolytes based on their clinical condition. If they are going into renal failure, they
may require less potassium, phosphorus. If they have increased losses via a nasogastric
tube or stool, they may require increased amounts of sodium or potassium. PN advancement is strongly dependent on laboratory
data, which is why we closely follow daily chemistries while they are advancing on PN. And once they are at goal calories via PN,
we follow weekly PN profile labs to ensure continued tolerance. On average, our patients reach goal energy
needs via PN by day three or four. It may take longer, closer to five to seven
days, if a patient is at increased risk for refeeding syndrome. But again, laboratory data closely determines
our advancement plan with PN. If a patient is on PN greater than one month
and continues to receive minimal or no enteral nutrition, we also monitor long term nutrition
labs to determine if additional micronutrients such as selenium or carnitine should be added
to our PN solutions, or if increased amounts of our micronutrients, such as zinc or copper
should also be included. That concludes my lecture on estimating energy
needs in a critically ill child and parenteral nutrition support. Thank you for your time. Please help us improve the content by providing
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