Lecture 2 An Overview of General Guidelines - Assessing Nutrient Requirements in Disease

Question 1

Fluid- how do you measure

Answer 1

Many methods
•See attachment
The first 2 methods (30-35ml/kg and 1ml/ kcal) are more standardized (method 2 used most often), while the others are more accurate but used less as it takes more time and the values have to be accurate

but you need to Modify for various diseases
Dehydration, lactation, certain kidney diseases, fever (sweating)
•When are fluid needs increased?
1. More advance kidney disease

Question 2

•What methods are used to establish target caloric intake?

Answer 2

1Looking at usual caloric intake
o Are relating on normal appetite
 Effect of disease or treatment (are they eating normally)
o Underlying assumption? Is that their intake is equal to their requirements. One way to see this is if their weight is stable.
 Works well in healthy active (normal and stable body weight) people as a guide to energy needs, assuming that the diet history is accurate)
 Eg. Controlled diabetes
2. Estimate of energy requirement using equations. Examples?
o Harris benedict
o WHO
3. Estimate using kcal/kg BW for various diseases.
o Examples:
o 30kcals/kg –HIV and AIDS
 Without infectection
o 35 kcals/kg – chronic pancreatitis
4. Measurement of energy requirement by Using indirect colrimetry

Question 3

What are the components of energy expenditure

Answer 3

• Basal metabolic rate
• Activity level
• Thermic effect of food- the energy it takes to digest food
• (the above ones are the normal components) Increased BMR due to disease, stress states

Question 4

how do we mesure BMR

Answer 4

• The energy required to carry out our body’s basic function, ex heart rate- the body resting and at fasting rate.
  What conditions is it ideally measured in? Its important to not doing any activity that day, fasting and right after you wake up, you would want the room to be quiet, comfortable temperature
  •BMR is impractical for the clinical setting, so RMR is measured.

Question 5

Resting Metabolic Rate (RMR)
what is it
how much higher is it compared to bmr
how is it measured

Answer 5

= energy expenditure measured at any time of day after the patient has quietly rested for 30 min.

MOST ACCURATE: indirect calorimetry – larger teaching/research hospitals
•Difference between BMR and RMR? 
	RMR would be about 20% higher
•What method is used to measure RMR?  
Indirect calorimetry

Question 6

what is measured during indirect calorimetry

What is the principle behind this measurement?

what 2 pieces of info fo you get

Answer 6

Oxygen and co2 INTAKE AND OUTAKE is measured

What is the principle behind this measurement?
O2 consumed is approximately directly related to energy produced as heat

• Volumes of litters of 02 consumed
  Look up the caloric equivalent (kcal of heat produced/unit time) for the amount of oxygen consumed
• Respiratory quotient (RQ) which= volum of co2 produced/volume of o2 consumed- find out what mixture of fuel (cho, fat, pro) is being metabolized

Question 7

How do you get to total energy requirement after you have measured RMR? What is missing?

Answer 7

Total energy requirement= measured RMR x activity factor (AF)
- 1.1-1.2 for bed ridden or hospitalized

Question 8

what values are important for calculating RMR

Answer 8

Basal metabolic rate (from the indirect caloremetry)
•Physical activity
•Thermic effect of food (don’t use this as we are overestimating the BMR)
•Energy cost of an increase in BMR caused by the disease (only some diseases- stress states)

Question 9

often using indirect calorimetry is not available, what do we do instead?

why can’t we use these equations for people who are overweight

Answer 9

Formulas commonly used for RMR?
-	Harris benedict- age, body weight, height and gender
-	WHO- gender, weight, age
-	other
WHO table 1.21 in handbook
Table 3.12 in textbook

o It would probably be too high (overestimate)
•Why?
o Fat is less metabolically active than lean body massand therefore will overestimate their energy requirement
What are the risks?
o They will gain more weight
o Is dangerous to overfeeding overweight people when they are critically ill
•Thus, a typical approaches to overcome this problem is:
If overweight – use ideal BW in equation OR correct in another way- to be discussed later.

Question 10

What is the total energy requirement equation

Answer 10

o Total energy requirement= estimated RMR x Activity Factor (AF)

Question 11

Protein Requirements

protein requirements change in other disorders depending on:

Answer 11

-RDA for protein is appropriate for some disorders in which protein requirement is unaffected. e.g. diabetes
•Adult RDA? 0.8g/kg
-Protein requirement changes in other disorders, depending on:
•previous nutritional status (malnourished?)
•rate of desired repletion
•if the disease increases protein requirement. e.g. stress states; kidney dialysis
•the amount of nonprotein energy being provided. Why? - need to make sure the body isn’t taking the protein from the muscles