Week 10 Flashcards
(22 cards)
WEEK 10
Energy Expenditure and Energy Requirements in Clinical Practice and Research
Clinical Example - slide 4
Research Example - slide 5
Components of energy expenditure
–> Total energy expenditure (TEE)
=
BEE =
PA =
TEF =
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(what methods would you use for our 2 examples)
slide 4 - Energy Eqn if lack of time // Indirect Calorimetry to compare to eqn if access to tools
slide 5 - We have more time and access… therefore Indirect calorimetry (such as Metabolic cart)
= TEE = BEE + PA + TEF
BEE = basal energy expenditure
PA = energy for physical activity or exercise
TEF = thermic effect of food
- sleeping metabolic rate and arousal
Basal Energy Expenditure (BEE)
– AKA ____
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– basal metabolic rate BMR
- energy needed for physiological functions to maintain life (i.e respiration, heartbeat)
- accounts for about 65-75% of TEE
- REE is AKA resting metabolic rate (RMR)
- person must be well rested during the measurement an in an environment that is not too hot or too cold (less restricted conditions than BMR)
- REE is thought to be about 10% higher than BEE
Conditions for measurement of BEE vs REE
–> BEE
–> REE
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- typically taken in a darkened room after approx 8 hours of sleep (night sleeping in the test facility), 12 hrs of fasting to ensure that the digestive system is inactive, and with the subject resting in a reclined position (not asleep)
–>
- typically taken under less restricted conditions than BEE; i.e rest for at least 30 min; no food for at least 2 hours before the test; normal room temperature and quiet surrounding (not asleep)
- more lean body mass, higher the REE
(men have higher REE) - REE decreases with age (about 2% decrease per decade after age 30)
- Restricted energy intake decreases REE
- Some ppl genetically have a higher REE
- Thyroid hormone levels
(more thyroid hormones, higher REE)
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Thermic effect of food (TEF)
- TEF is…
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[energy for hypermetabolic conditions is also a component of TEE in acute care]
VISUAL graph - slide 15
- can vary a lot depending on type, time and intensity of PA
- Usually accounts for 20-25% of TEE (less in hospitalized patients, and more in athletes)
- is the energy needed for absorption, transport and metabolism of nutrient intake
- estimated to be 10% of caloric intake {expenditure}
(lg meals have a greater TEF) (Protein has a higher TEF than Fat or CHO) - TEF is highly variable and hard to estimate - therefore, not included in calculations of energy requirements
Direct calorimetry & indirect calorimetry
Direct =
Indirect =
- conducted using…
DISADV - ## measurement takes…-
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[Isothermic conditions - total energy from metabolism: ~40% from ATP / ~60% from heat] - slide 18 VISUAL
D = measures heat production
I = measures gas exchange: oxygen consumption and carbon dioxide production
- all energy used by the body is ultimately dissipated as heat
- using a special chamber that measures the amount of heat given off by the body
DISAD - takes many hours (from 24 hours to a number of days)
- very expensive and inaccessible (expensive to build and requires at least 1 full-time technician)
- highly impractical for large-scale studies
- b/c of confined space, chambers don’t provide an accurate estimate of an indiv free-living activity energy expenditure
INDIRECT CALORIMETRY
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–> Used in research at the U of G
–> Energy metabolism depends on oxygen consumption (VO2) and carbon dioxide production (VCO2)
- VO2 and VCO2 are measured, or estimated in order to calculate REE (can be in chamber/room or with a mask)
–> (not heat its O2/CO2)
- volumes of inspired and expired air are measured
- gas analyzers measure the concentration of O2 and CO2 in inspired and expired air
–> Used in clinical practice for pts with extreme metabolic stress
- also Indirect cal is more accurate than an energy expenditure eqn in obese pts
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SLIDE 24 - review
- Lightweight and portable calorimeter
- Less technical expertise is needed and cheaper
- Person hold the device and breathes into a mask or mouthpiece (while wearing a noseclip)
—- ONLY O2 is measured
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The isotopes…
The pt provides…
Then
Calculated CO2 produced is used to…
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- Gold standard for measuring energy expenditure in free-living persons over a 1- to 2 week period
- Must drink a known volume of water containing two stable isotopes: 2H2O and H2 18O
… mix with the body’s water and are eliminated over time. 2H is lost only as water (in urine) and 18O is lost as water (in urine) and carbon dioxide (exhaled)
… urine samples over 1-2 week period to measure the rate at which the isotopes are eliminated - the difference in elimination rates is proportional to CO2 production (add up the 2H and 18O excreted then subtract from what was ingested)
… to calculate energy expenditure (just like indirect calorimetry)
-Non-invasive, safe and accurate
-Expensive
-2 weeks is a lot of urine to collect
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[Can use published values for energy expenditure associated with each level of activity - add up energy expended over the course of the day]
- keep a careful record of activity levels throughout the day (ie. dominant activity level for every 15 min period over 24 hours)
METs =
Scores for different activities
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** SLIDE 33 do the calculations **
[Alternatively, activity monitors (such as pedometers or accelerometers) could be used to estimate energy expenditure (might be different than the measured levels)]
= The metabolic equivalent of task, A MET is also defined as oxygen uptake in ml/kg/min, with one MET equal to the oxygen cost of sitting quietly, equivalent to 3.5ml/kg/min
- Published values were derived using indirect calorimetry
- METs values may not be known for all ranges of physical activities
Energy Intake
- If the person is in energy balance (not gaining or losing wt) =
Using equations…
[Often, it is more practical to estimate energy requirements using equations
→ Many prediction equations have been developed using different populations]
Which eqn should I use?
- Accuracy is best when an eqn is applied to persons who…
= energy intake will equal energy expenditure
- who closely match the population the eqn was developed upon
- use condition-specific eqns when avail (ie. eqns for pts with burns)
Which body weight should I use?
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[why can’t use actual body wt usually… increased wt isn’t usually metabolically active muscle - it’s usually fat, therefore overestimating metabolism]
- in critically ill patients (overwt/obese) - suggest to use ideal body wt –> don’t want to risk overfeeding
slide 41 has more points - READ
–> Could use actual body weight, ideal body wt or adjusted wt for obese pts
- b/c the high body wt observed in severe obesity is mainly due to an increased body fat mass, with lower metabolic rate than body cell mass, the use of actual body wt in prediction eqns may fail to accurately estimate REE
[may result in overfeeding]
- use of adjusted body wt instead
[could result in underfeeding] - if obese persons were included in the sample used to develop the eqn for REE, there is no need to use a different weight
[could use actual body wt]
ie. the Mifflin-St Jeor eqn was derived from a sample of 498 normal-wt, overwt and obese and severely obese individuals ages 19-78 yrs old
What is PEM?
WEEK 10
Assessment of Protein-Energy Malnutrition
AKA
Biochemistry of PEM
- to understand the signs of PEM, we need to understand the body’s adaptations to low kcal and protein intakes
= a form of malnutrition in which patients are not meeting their protein and/or energy needs
AKA protein-energy deficiency, energy-pro deficiency, multi-nutrient defi, energy nutr defi, pro-calorie malnutrition
Adaptations during starvation
–> Short term fasting ( )
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–> Fasting days ( )
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** Glycogenolysis =
VS
Gluconeogenesis =
–> (<24 hours)
- body breaks down glycogen for glucose
–> (2-3 days)
- primary fuel source is fat
- liver, kidney and muscle protein produce some glucose through gluconeogenesis [glucose produced from non glycogen sources] for utilization in the brain and RBCs
lysis = the biochemical pathway in which glycogen breaks down into glucose-1-phosphate and glucose.
neogenesis = The process of making glucose (sugar) from its own breakdown products or from the breakdown products of lipids (fats) or proteins
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– Altered hormonal regulation of body processes
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- study on slide 8 - during fasting the actions of growth hormone are blocked by a fat-burning hormone called FGF21*
SLIDE 9 - VISUAL look at
–> (3+ days)
- fat is the primary fuel
- metabolic rate is lowered (slower breathing, slower heart rate)
- ketone bodies are produced to feed the brain (beta-oxidation) (preserves muscles from being broken down for glucose)
- muscle protein is broken down for energy (vital proteins are prioritized (ones that are not as essential) (EX: heart and lung muscle may initially be preferentially spared, disproportionate amount of peripheral skeletal muscle is lost)
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- Fewer blood cells, proteins and lipoproteins are made
- Fewer immune proteins are made
- Production of some enzymes is decreased
- Collagen synthesis is decreased
–>
- Higher levels of growth hormone, but lower growth hormone action (not as effective)
- does not reduce net protein catabolism, and does not help conserve body protein stores
- lower levels of thyroid hormones are produced
TWO types of PEM:
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–> Marasmus
- often occurs in younger children (6-18 months)
-very low intakes of both protein and energy over a long period of time
–> Kwashiorkor
-“The disease the 1st child gets when the second is born”
- occurs in the older children (1-3years)
- very low protein intakes; usually sudden change in intakes
- ie. children are weaned from breast milk and given a poor substitute
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S&S (name 4) - more on slide 12
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- most often seen in very young children in developing nations
- is seen in CAN among pts with severe wasting (AIDS, Cancer, Tuberculosis, Anorexia)
S&S
- Pot belly, sparse dry hair, old persons face & worried look, dry wrinked skin, extremely low wt (<60% of reference wt),
loss of fat and muscle, wasting
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- ## imbalance btw….
- infection may induce…
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- seen most frequently in children 1-3 years of age (but may occur at any age)
- Kwashiorkor tends to develop quickly due to sudden change in intake - severe protein deficiency
- MAY HAVE adequate CHO intake
- …btw CHO and protein intakes may cause poor metabolic adaptation in kwashiorkor (body proteins may not be as well preserved)
- Oxidative stress seen in kwashiorkor points to imbalance in antioxidant systems –> damage of body tissues
- …. extra muscle loss rather than fat loss in Kwashiorkor (muscle wasting, less fat wasting)
- Edema in the legs, arms and even face!!! (why wt loss isn’t as severe) (edema happens due to hypoalbuminia [low albumin - leads to water leak to interstitial space)
- round moon-like face, mod-low wt loss due to edema, sparse hair, pale flaky skin
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- Extremely low body wt (<60% of reference wt)
- Edema (usually milder, just in the legs)
- Muscle and fat wasting (like in marasmus)
- Other changes may develop, including skin changes, hair changes, mental changes and hepatomegaly
WELLCOME classification of severe forms of PEM
- slide 18
Comparison of the features of kwashiorkor and marasmus - slide 19
Biochemical differences btw Marasmus and Kwashiorkor - slide 20
* focus on –> (4) * - understand
- –> Free fatty acids,
Urine creatinineCreatinine from muscle contraction = waste product — body is preserving muscle therefore less creatinine in blood/urine
+ Urine hydroxyproline developed from collagen utilization – AKA collagen metabolite — using less collagen/breaking down less as response to PRO malnutrition
Glucocorticoids
(hormones - mobilize AA for breakdown, promote gluconeogenesis, mobilize fat breakdown — more stress on body in Marasmus)
Things to remember about PEM
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- Slide 22 - VISUAL shows cycle of infection * VIEW
–> Pro and energy are seldom the only nutr deficiencies
- often iron, zinc, iodine, Vit A, folic acid deficiencies as well
- can compound the problems
–> Infections, parasitic infections and diseases are also common
- can compound problems and make protein status difficult to measure, causes are hard to pin down
Complications of PEM
6 -
Diagnosis of PEM
– Severity is mostly assessed through ____
(classification of severity of PEM - chart slide 24)
EXAMPLE - slide 25 - practice
Diagnosis of PEM con’d
– Course of disease
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– Cause
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– Confirmation
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- malnutrition video slide 29 *
1 Diarrhea 2 Dehydration 3 Infections 4 Hypoglycemia 5 Anorexia 6 Anemia
- ___ anthropometry ____
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- measured through growth history & diet history
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- relative contribution of low kcals and low protein intake & clinical assessment (including history of diseases & infections)
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- Biochemical and clinical signs
