Hospital Based Nutrition Flashcards
Many people who are admitted to the hospital are unable to feed themselves.
a. This can be the result of alterations in their level of consciousness, respiratory failure with intubation and ventilation, neurological problems that impair their ability to protect their airway when swallowing, problems with their gastrointestinal tract that make food intake contraindicated and other problems.
b. In these individuals there is only two choices, feed them or not.
c. The issue of nutritional support in the hospital is rarely a critical decision and as a result it often is not addressed very systematically, especially on non-surgical services.
The basic questions that you need to answer in this situation are:
- When to feed (on admission? Day 2? Day 10 of hospitalization?)
- By what route (enteral or parenteral),
- How to write the initial diet orders,
- How to monitor the adequacy of feeding when it is administered over time,
- Special issues raised by the presence of pulmonary, liver or kidney disease.
When to feed?
a. When a patient is admitted who is unable to feed him/herself the clinician needs to decide if they need to provide nutritional support on the day of admission or if this issue can wait for some time (1, 2, 5 or 20 days?).
b. The decision of when to feed someone depends on four factors:
- The patient’s preexisting nutritional status,
- The patient’s level of illness
- The consequences to the patient of inadequate nutrition
- The risks of feeding them
When a person is ill and is not able to eat, they begin to rely on stores of these biomolecules.
a. As a result, the stores of energy, macronutrients, vitamins and trace elements begin to shrink.
b. After some period of time, the pool sizes of these substances reach a level where there are not enough of them for the body to function normally.
c. The body becomes deficient in one or more of these and the person’s ability to maintain homeostasis and fight the underlying illness may be impaired.
d. How long can a person go without eating before they deplete stores of critical molecules to the point that health may be impaired?
i. There is no one right time point.
e. However, as you might guess, if the person is malnourished to start with then they will suffer consequences of poor nutrition sooner than someone who had good pre-morbid nutrition.
You might then ask yourself when the depletion will reach a point that you think it will impair functioning.
Some general guidelines are:
- Previously well nourished adult who cannot eat but who has minimal acute medical illness:
i. Might go 10-14 days without food before they begin to develop potentially serious nutritional deficiencies. - Previously undernourished adults with minimal medical illness, or previously well nourished individuals with serious acute medical illness (infection, surgery, cancer):
i. Might go 5-7 days without food before they begin to develop potentially serious nutritional deficiencies - Previously undernourished adults with serious medical illness: may develop potentially serious nutritional deficiencies in 3-5 days if they are not fed.
* These numbers will be substantially shorter for infants and children as they have smaller pool sizes and increased nutrient needs due to growth and development.
You might then ask yourself when the depletion will reach a point that you think it will impair functioning.
Some general guidelines are:
- Previously well nourished adult who cannot eat but who has minimal acute medical illness:
i. Might go 10-14 days without food before they begin to develop potentially serious nutritional deficiencies. - Previously undernourished adults with minimal medical illness, or previously well nourished individuals with serious acute medical illness (infection, surgery, cancer):
i. Might go 5-7 days without food before they begin to develop potentially serious nutritional deficiencies - Previously undernourished adults with serious medical illness: may develop potentially serious nutritional deficiencies in 3-5 days if they are not fed.
Some general guidelines for when nutrition impairs function
- Previously well nourished adult who cannot eat but who has minimal acute medical illness: Might go 10-14 days without food before they begin to develop potentially serious nutritional deficiencies.
- Previously undernourished adults with minimal medical illness, or previously well nourished individuals with serious acute medical illness (infection, surgery, cancer): Might go 5-7 days without food before they begin to develop potentially serious nutritional deficiencies
- Previously undernourished adults with serious medical illness: may develop potentially serious nutritional deficiencies in 3-5 days if they are not fed.
* These numbers will be substantially shorter for infants and children as they have smaller pool sizes and increased nutrient needs due to growth and development.
How do you assess a patient’s pre-morbid nutritional status and energy expenditure?
a. Don’t overlook the value of simple clinical observation: the history and physical examination.
b. Patients who are alcoholic, homeless, underweight, have signs of muscle loss or cachexia, have chronic diarrhea or other GI disturbances, who self-report poor dietary intake, have chronic medical problems that increase their energy expenditure
i. have insensible losses of nutrients because of proteinuria, mucous production, bleeding etc should be considered to possibly have pre-existing nutritional insufficiency.
c, Patients who have a fever, an increased WBC, tachycardia, a rapid respiratory rate, drainage from operative sites or sites of infection, are healing wounds, have substantial proteinuria etc would be expected to have increased need for nutrients.
After you’ve decided “When” to feed the patient
Then you take a number of steps before you can actually feed them.
a. This includes steps such as placing a feeding tube, or an intravenous line that can be used for parenteral feeding and making sure these tubes are in the right place.
b. Why not feed everyone immediately upon admission to the hospital?
i. Because there is some risk involved.
ii. To feed someone who is not able to feed themselves requires food to be delivered either enterally (via a tube inserted into the GI tract either via the mouth, nose or through the abdominal wall) or parenterally (intravenous feeding).
c. The risk of enteral feeding is principally aspiration of food into the lungs which can be a potentially life threatening problem.
i. Parenteral nutrition carries a number of risks perhaps the greatest of which are the risks of placing a central venous catheter and the risk of infection from a central line that contains nutrients in high concentration.
d. Whenever possible, nutrients should be delivered via the enteral route.
i. The risks are lower and there are benefits to delivering the nutrients by the normal physiological route including nourishing the GI epithelium which is important in long term nutrient absorption and acts as a barrier to colonic flora.
Why not feed everyone immediately upon admission to the hospital?
Because there is some risk involved.
a. To feed someone who is not able to feed themselves requires food to be delivered either enterally (via a tube inserted into the GI tract either via the mouth, nose or through the abdominal wall) or parenterally (intravenous feeding).
b. The risk of enteral feeding is principally aspiration of food into the lungs which can be a potentially life threatening problem.
c. Parenteral nutrition carries a number of risks perhaps the greatest of which are the risks of placing a central venous catheter and the risk of infection from a central line that contains nutrients in high concentration.
d. Whenever possible, nutrients should be delivered via the enteral route.
i. The risks are lower and there are benefits to delivering the nutrients by the normal physiological route including nourishing the GI epithelium which is important in long term nutrient absorption and acts as a barrier to colonic flora.
Whenever possible, nutrients should be delivered via the enteral route.
The risks are lower and there are benefits to delivering the nutrients by the normal physiological route including nourishing the GI epithelium which is important in long term nutrient absorption and acts as a barrier to colonic flora.
The risk of enteral feeding is principally aspiration of food into the lungs which can be a potentially life threatening problem.
If you have chosen to feed a person by the enteral route, you next select a “formula” from the available options at your hospital.
a. Most hospitals have a standard liquid formula that contains fat, protein, carbohydrate, vitamins and trace elements at a level that should provide adequate nutrition.
b. The sources of the macronutrients are often corn oil, maltodextrin (starch) and casein (milk protein).
c. The typical energy density is 1 kcal/ml, although there are often a number of types of enteral formulae that could be used for particular situations where there are unique needs. .
So next you need to decide how many calories to feed your patient.
(after picking enteral route and formula)
a. Here again there are formulae that you can use to calculate or estimate this (like what you have used in your diet self monitoring exercise).
b. Sick people in the hospital typically have very low levels of physical activity, and so PAEE is low.
c. However, medical illness can markedly increase resting energy expenditure.
i. A general range of TEE for sick people might range from 22-25 kcal/kg/day for someone who is not that sick to 30-32 kcal/kg/day for someone who is very sick.
d. You then take the person’s weight in kg times a number of kcal/kg/d that you think is appropriate to calculate the person’s daily energy needs.
i. Since the enteral diet comes in 1 kcal/ml, the number of kcal/day that they need equals the number of ml/day that you need to infuse via the tube.
e. You then divide that number by the number of hours in the day to get an hourly infusion rate.
Most people will not tolerate starting enteral feeding at an infusion rate necessary to meet their total daily energy needs.
a. They may have trouble emptying that volume of diet from their stomach and as a result may vomit and aspirate.
b. For this reason you should start with a lower infusion rate and gradually increase the flow rate of the diet over a period of days.
c. You can check “residuals” (the amount of food still in the stomach) periodically and if the stomach is filling up with formula wait for a bit and restart the diet at a slower infusion rate.
d. Many people are laying flat on their back if they are on a ventilator or sedated.
e. Putting the patient on their right side (right lateral decubitus position) and/or elevating the head of the bed a little may facilitate gastric emptying in this situation
Why giving them nutrients is important, even at a low rate
a. Even if you are not able to give an enteral diet at a rate that is sufficient to meet total daily energy needs it is helpful to at least give some modest amount of enteral feeding to ‘feed the intestine’ as this will help maintain the barrier function of the gut.
b. In addition, if you cannot give a full diet by enteral feeding, remember to give vitamins, and micronutrients to all patients that you suspect may be malnourished.
c. Most importantly you need to remember to give thiamine and folate and a multiple vitamin (which can be given intravenously) to potentially malnourished individuals as you give them intravenous glucose.
Critical Nutrients to give the patient
a. Most importantly you need to remember to give thiamine and folate and a multiple vitamin (which can be given intravenously) to potentially malnourished individuals as you give them intravenous glucose.
b. Intravenous glucose is typically administered as “D5” which is 5% dextrose in water.
i. If this is delivered at 100 ml/hr you are giving 5 grams of glucose per hour (20 calories/hr).
c. If you deliver that over 24 hours you will be giving 120 grams of glucose over the day.
i. This amounts to a 480 calorie 100% carbohydrate diet.
d. While this will spare some muscle breakdown that would otherwise occur to provide amino acids for gluconeogenesis, it is not a nutritionally complete diet as it lacks vitamins, micronutrients, essential amino acids and essential fatty acids.
How to monitor the adequacy of feeding?
a. If someone is going to need tube feedings for a long time (months), then you may want to check to see if your “guess” about their energy needs is actually appropriate to meet their ongoing needs.
b. Errors can be made in either direction, you might be “over-feeding” a person, giving them more calories than they can assimilate, or you might be underfeeding them, not giving enough calories to meet their daily energy needs.
c. If you are over-feeding a person, they will tend to do fine for several days as they fill up their glycogen stores (which may have been depleted over the initial part of the hospitalization during which they were not being fed).
i. Then, once their glycogen stores are filled they will tend to develop hyperglycemia.
ii. This hyperglycemia may be difficult to control with insulin as the “cupboard is full”.
iii. When you see someone who is becoming hyperglycemic while receiving an enteral diet, ask yourself if you might be over-feeding them.
iv. If you then reduce the number of calories that they get each day, it may take several days for the situation to reverse itself
d. If on the other hand you under-feed a person, what you will find is that they are in negative nitrogen/protein balance.
i. By this I mean that they are breaking down muscle to donate amino acids to gluconeogenesis to produce glucose for their brain.
ii. If they are breaking down more protein than you are feeding them, then they will lose weight over time.
iii. You can estimate how much protein is being broken down by measuring urinary nitrogen over 24 hours.
If you are over-feeding a person, they will tend to do fine for several days as they fill up their glycogen stores
(during long-time feeding, like months)
a. If you are over-feeding a person, they will tend to do fine for several days as they fill up their glycogen stores (which may have been depleted over the initial part of the hospitalization during which they were not being fed).
b. Then, once their glycogen stores are filled they will tend to develop hyperglycemia.
c. This hyperglycemia may be difficult to control with insulin as the “cupboard is full”.
d. When you see someone who is becoming hyperglycemic while receiving an enteral diet, ask yourself if you might be over-feeding them.
e. If you then reduce the number of calories that they get each day, it may take several days for the situation to reverse itself
If on the other hand you under-feed a person, what you will find is that they are in negative nitrogen/protein balance
a. If on the other hand you under-feed a person, what you will find is that they are in negative nitrogen/protein balance.
b. By this I mean that they are breaking down muscle to donate amino acids to gluconeogenesis to produce glucose for their brain.
c. If they are breaking down more protein than you are feeding them, then they will lose weight over time.
d. You can estimate how much protein is being broken down by measuring urinary nitrogen over 24 hours.
i. The nitrogen that appears in the urine came from the catabolism of amino acids.
ii. An estimate of the number of grams of protein that were catabolized can be made by multiplying the number of grams of urinary nitrogen by 6.25 (an empirically derived number that reflects the ratio of grams of protein/grams of nitrogen for the “average protein”).
e. The number of grams of protein that you are feeding that person can be found by looking at the label of the formula to see how many grams of protein are contained in each liter of the product and multiply that by the number of liters/day that you are feeding the person.
f. There are other sources of nitrogen loss via the stool and skin (and fluids that may come from the lungs, surgical drains, chest tubes or abscess sites).
g. If the number of grams of protein that they are losing each day is greater than the number of grams of protein that you are feeding them then they are in “negative protein balance” and you should consider increasing the amount of food you are giving each day.
i. An average protein requirement for sick patients is 0.8-1 g protein/kg body weight/day.
