NR Flashcards
Things that can influence nutritional requirements
Things that can influence nutritional requirements:
* Route of feeding: oral, enteral tube, parenteral
* E.g. reduced fluid requirements in parenteral may be observed due to other fluid sources.
* Parenteral feeding routes have different electrolyte requirements to oral
What does the estimation of nutritional requirements depend on?
Estimation of nutritional requirements depends on:
* Accuracy – no single validated method
* Clinical circumstances
* Sickness or health
* Population the equation was studied in
Factors that affect energy expenditure
Factors that affect energy expenditure:
* Drugs
* Body Composition
* Diet
* Climate
* Hormones
* Physical activity
* Psychological state (higher EE in anxiety)
* Disease and injury
What is the thermoneutral zone?
Thermoneutral zone:
* The thermoneutral zone is defined as the range of ambient temperatures where the body can maintain its core temperature solely through regulating dry heat loss, i.e., skin blood flow.
* It is 26-29 oC
Factors affecting energy expenditure (more detail)
- ** Body composition:**
Differences between ages and sexes
Women generally have a higher % of body fat than men.
A decrease in bone mass and lean mass and a reciprocal increase in fat mass, are often observed in normal populations. -
Climate:
Thermoneutral zone = 26-29 C -
Diet:
Quality
Quantity -
Disease state
Stress response: starvation (refeeding risk) vs trauma (ebb and flow phases)
Pain effects -
Drugs/medication
Sedation/anesthesia/paralysing agents: decreased gut mobility / reduced gastric emptying
Steroids: anabolism: increase intake
Stimulants e.g., tea/coffee
Opioids: constipation -
Hormones:
Stress hormones:
corticotropin-releasing hormone (CRH) might partially explain the anorexigenic effects of acute stress. CRH can also stimulate the sympathetic nervous system and catecholamine release, inducing hypophagia and weight loss, through their effects on the liver and on white and brown adipose tissue. Chronic stress can lead to dietary over-consumption (especially palatable foods
Thyroid dysfunction: hyperthyroidism: increases metabolic rate. Hypothyroidism: reduces metabolic rate -
Physical activity:
Duration & intensity
Individual’s fitness -
Psychological state:
Anxiety
Total Energy Expenditure (TEE) IN HEALTHY INDIVIDUALS
**TEE = BMR + DIT + PAL ** IN HEALTHY
BMR = most dominant part of TEE (60 %)
= metabolic activity for life e.g., respiration, heat etc.
**DIT = **energy expended in nutrient digestion/absorption/transport
**PAL = **physical activity level
Total Energy Expenditure (TEE) IN metabolically stressed INDIVIDUALS
In stressed individuals:
TEE = BMR + DIT + PAL + stress factor
Difference in TEE between healthy and metabolically stressed
Difference in TEE between healthy and metabolically stressed
Healthy: Higher activity level, no stress factor
Metabolically stressed: lower activity level, stress factor present, increased BMR, same DIT
Different ways to estimate energy requirements (excluding IC)
- Weight multiplication factors
e.g., 25-35kcals/kg/day
25-30kcal/kg/day - Predictive equations – BMR only
E.g., Henry, 2005 = Oxford equation - Current intake +/– for weight gain/loss
- DRVs – e.g., Estimated Average Req (EAR)
The guidelines in the PENG Handbook have ? been developed for therapeutic diets or for weight modification
The guidelines in the PENG Handbook have not been developed for therapeutic diets or for weight modification
Advantages and limitations of weight multiplication factors
Advantages and limitations of weight multiplication factors:
In critical care it is important to use ? ? rate to prevent excess CO2
Critical care = important to use glucose oxidation rate to prevent excess CO2
Acute illness can increase BMR by ?
Acute illness can increase BMR by 40-100%
What are the most accurate methods for determining energy requirements?
The most accurate methods for determining energy requirements:
* Indirect calorimetry (becoming more accessible in clinical practice, expensive)
* Doubly labelled water (impractical and expensive)
Limitations of kcal/kg of body weight
Limitations of kcal/kg of body weight:
* Doesn’t account for changes in energy expenditure related to age, gender or metabolic state
* Unclear whether actual or ideal body weight should be used for obese
* No defined criteria as to which value is most appropriate