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
All estimates of energy requirements should be ? and used as a starting point only
All estimates of energy requirements should be interpreted with care and used as a starting point only. They should be reviewed and recalculated regularly to avoid under or overfeeding.
Advantages and Disadvantages of Weight multiplication factors
Advantages and Disadvantages of Weight multiplication factors
Advantages
* Quick
* Easy to use and remember
* Often have a range
Disadvantages
* Some of them don’t require a PAL and have incorporated a PAL into them already which can make them less individualised to a patient
* If it is not based on fat free mass, may lead to overestimation
* Does not account for other factors that may affect metabolism such as a ventilator like PSU
When is it suggested to use a stress factor?
It is suggested to use a stress factor if there is evidence of an inflammatory response:
* C-reactive protein (CRP) & low serum albumin
* High white cell count
* Oedema
Why I wouldn’t use a stress factor if patient is metabolically stressed:
Why I wouldn’t use a stress factor if patient is metabolically stressed:
* Depending on the phase, there could be an inability to utilise reserves, body could be in a catabolic state (likely if acutely unwell).
* Overfeeding can increase mortality
* Studies show that an increase in nutrition doesn’t prevent the natural losses during acute illness
* The evidence for the use of stress factors isn’t clear
* Increased energy: increases co2 production which for may lead to increase time on ventilator and increased length of stay, hyperglycaemia, and electrolyte imbalances.
Current intake +/- for weight gain or loss
Current intake +/- for weight gain or loss
* For underweight the addition of 400-1000 calories in PENG
* Weight loss: probably more useful to analyse current intake and remove from there
Advantages and disadvantages of DRVs
Advantages and disadvantages of DRVs
Advantages
* Gives an idea of a “healthy” intake for different age ranges & sexes
* Based on healthy populations
* Ideal for public health
Disadvantages
* Population based so not individualised
* Enervy DRVs: Includes a PAL: 1.63: different people have varying levels of physical activity
* Energy DRVS: based on a BMI of 22.5 (limitations of BMI)
* According to SACN 2011: likely to underestimate for those with obesity?
* Utilitsed the HENRY equation
* Based on healthy populations: can’t be used in sick.
* Current DRVs published in 2016: how would requirements differ now
* RNI: 97.5% will meet requirement, 2.5% will need more
* LRNI: 2.5% will meet requirements, 97.5% will need more
* EAR: 50% will need more, 50% will need less
Considerations for estimating protein requirements
Considerations for estimating protein requirements
* PENG state estimation of protein with their values could lead to underestimation in underweight but overestimation in obese/overweight
* BMI >30: 75% of estimation based on ABW (PENG)
* BMI >50: 65% of estimation based on ABW (PENG)
*
Estimating protein requirements GENERAL (PENG TABLE)
Estimating protein requirements GENERAL (PENG TABLE)
* < than 18.5kg/m2: 1.0-1.5g per kg BW per day but needs are likely to be 1.5g/kg BW/day. Start with this and monitor
* 18.5-30kg/m2: 1.0-1.5g. For those with a lower BMI the g protein per kg BW are likely to be **higher. **
* >30kg/m2: Use approximately 75% of the value estimated from the actual weight
* >50kg/m2: Use approximately 65% of the value estimated from the actual weight
Protein requirements in post injury/anabolic/recovery phase (Elia, 1994)
Protein requirements in post injury/anabolic/recovery phase (Elia, 1994)
* Up to 1.9g pro/kg/day
What does N balance depend on?
N balance depends on past and recent energy intake, metabolic state, physical activity and protein levels.
Where are particulary large protein losses observed?
Large protein losses are typically observed in sepsis, major trauma and burns
Estimation of protein requirements in elderly (studies)
Estimation of protein requirements in elderly (studies)
* PROT-AGE study suggested intake of 1.0g-1.2g/kg/day in older adults
* Dorrington et al.’s review also suggests 1.2g/kg/day
* ESPEN: minimum of 1.0g/kg/day but up to 2.0g/kg/day if malnourished.
Estimation of fluid considerations
Estimation of fluid considerations
* Differences between parenteral & enteral
* Enteral: Original data between 60
-100years old .Equations difficult to ascertain and primary source not identified . Original references not cited. One equation based on two human subjects. Use as a guide and monitor.
Enteral:
* 18-60 years old: 35mls/kgbwt/day
* > 60 years: 30mls/kgbwt/day
Apyrexia
APYREXIA is absence or intermission of fever
If there are no ranges listed for energy requirements in PENG that means it has come from what amount of studies?
If there are no ranges listed for energy requirements in PENG that means it has come from only 1 study
Considerations for monitoring
Considerations for monitoring
Is prescription being delivered? - food record charts, IV charts, fluid charts
Weight change (beware rapid changes = fluid)
Anthropometry
Clinical condition
Biochemical markers
Absorption markers e.g., vomiting, diarrhoea
Urine output
Abnormal fluid status
Abnormal fluid status:
* Oedema and ascites increase body weight, but no additional metabolically active tissue.
* Dry weight should be calculated:
* Last recorded weight prior to oedema
* Estimate dry weight
* Weight minus drained weight
PENG Ascites or Oedema values
PENG Ascites or Oedema values
Ascites
* Minimal: 2.2kg
* Moderate: 6.0kg
* Severe: 14.0 kg
Oedema
* Minimal: 1.0kg
* Moderate: 5.0kg
* Severe: 10.0 kg
Vits and minerals
DRVs (EAR/RNI/LRNI): mg/ug per day
Oral vs. parenteral requirements -
Consider:
Maintenance
Treatment of depletion/deficiency
