current evidence for estimating energy requirements clare soulsby, research dietitian
TRANSCRIPT
![Page 1: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/1.jpg)
Current Evidence for Estimating Energy Requirements
Clare Soulsby, Research Dietitian
![Page 2: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/2.jpg)
Main components of energy expenditure:
– basal metabolic rate (BMR)– alteration in BMR due to disease process
(stress factors)– activity– diet induced thermogenesis (DIT)
![Page 3: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/3.jpg)
Estimating BMR: controversies
basal metabolic rate (BMR) vs. resting energy expenditure (REE)
prediction equations vs. measured energy expenditure (MEE)
![Page 4: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/4.jpg)
Conditions essential for measuring BMR
post-absorptive (12 hour fast) lying still at physical and mental rest thermo-neutral environment (27 – 29oC) no tea/coffee/nicotine in previous 12 hours no heavy physical activity previous day gases must be calibrated establish steady-state (~ 30 minutes)
* if any of the above conditions are not met = REE
![Page 5: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/5.jpg)
Estimating BMR: controversies
basal metabolic rate (BMR) vs. resting energy expenditure (REE)
prediction equations vs. measured energy expenditure (MEE)
![Page 6: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/6.jpg)
Estimating BMR: prediction equations
may over or under-estimate (compared with MEE)
inadequately validated poor predictive value for individuals open to misinterpretation
(Cortes & Nelson, 1989; Malone, 2002; Reeves & Capra, 2003)
![Page 7: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/7.jpg)
![Page 8: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/8.jpg)
Estimating BMR:which equation?
• Harris-Benedict
• Schofield Equations
• disease specific eg Ireton Jones
• Kcal/kg
![Page 9: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/9.jpg)
Estimating BMR: Harris Benedict Equations
• Developed in 1919• From data collected between 1909 and 1917
(Harris Benedict 1919)
• Study population: – 136 men; mean age 27 ± 9 yrs, mean BMI
21.4 ± 2.8– 103 women; mean age 31 ± 14 yrs, mean BMI
21.5 ± 4.1• Tends to overestimate in healthy individuals
(Daly 1985, Owen 1986, Owen 1987)
![Page 10: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/10.jpg)
Estimating BMR: Schofield Equations
• developed in 1985 (Schofield 1985)• meta analysis of 100 studies of 3500men and
1200 women• studies conducted between 1914 and 1980
(including Harris Benedict data)• 2200 (46%) subjects were military Italian adults • 88 (1.2%) subjects were >60 years • SE 153-164kcal/d (women) 108 -119kcal/d
(men) (Schofield 1985)
![Page 11: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/11.jpg)
Estimating BMR: disease specific equations
• developed for specific patient groups (Ireton Jones 1992, Ireton Jones 2002)
• advantage over Schofield/ HB equations:– Schofield /HB estimate BMR of a healthy
individual then necessary to adjust for disease using a stress factors
– disease specific equations include patients in their database so aim to more accurately reflect BMR of hospitalised patients
![Page 12: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/12.jpg)
Estimating BMR: Ireton-Jones energy equations
• ventilated and breathing ICU patients
• 3 x 1 minute measurements 200 patients
• unclear whether measurements took place during feed infusion/ after treatment etc
• 52% burns, 31% trauma
• validation studies, IJEE had a better agreement with MEE: – HBx1.2, HBx1.3, 21kcal/kg
![Page 13: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/13.jpg)
Estimating BMR• Schofield equation derived using meta analysis:
– greater power than small/ local studies
• compiled from unstructured data set obtained for diverse reasons:– problems with sampling assumptions
• accuracy approx ±15%• disease specific equations useful in some
circumstances
![Page 14: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/14.jpg)
Estimating BMR
• what about:– the elderly?– the obese?
![Page 15: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/15.jpg)
Estimating BMR: the elderly
• Original Schofield equations:– only 88 (1.2%) of subjects >60 years– particularly unsuitable for >75yr– included data on subjects from the tropics
• Revised equations for the elderly:– published in the 1991 COMA (DH 1991)– include additional data from 2 studies; 101
Glaswegian men (60-70yr) 170 Italian men and 180 Italian women
– excluded data collected in the tropics
![Page 16: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/16.jpg)
Estimating BMR: Obesity
• equations (such as Schofield) are linear• weight increases linearly with estimated BMR• may overestimate in obese
weight
BMR
![Page 17: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/17.jpg)
Estimating BMR: obesity
BMI % of Schofield database
% of UK population (DOH 1999)
> 25 14.6% 40.8%
> 30 4.5% 9.7%
![Page 18: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/18.jpg)
Estimating BMR: Obesity
• obese data primarily obtained from 2 groups:– Burmese hill dwellers– retired Italian military
• there were significant differences in weight/ BMR association between groups, Italian group showed greatest difference
• obese subjects in Schofield data may not be a statistically representative sample of the population is general
![Page 19: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/19.jpg)
Estimating BMR: Obesity
• recent (Horgan 2003) reassessed validity of the Schofield data to predict BMR in obese
• conclusions:– BMR increases more slowly at heavier weights– to ignore this is to over predict energy requirements– any general equation for predicting BMR may be
biased for some groups or populations.
![Page 20: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/20.jpg)
Estimating BMR: adjusted body weight (ADJ)
estimate of how much of the extra body weight is lean and thus metabolically active
2 methods: 25% adjusted weight
= (actual body weight x 0.25) + ideal body weight
adjusted average weight = (actual body weight + ideal body weight) x 0.5
![Page 21: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/21.jpg)
Estimating BMR: adjusted body weight (ADJ)
first reported in newsletter Q&A format not validated studies suggest adjusted average weight
has better predictive value than 25% adjusted weight (Glynn 1998, Barak 2002)
no longer included in ASPEN guidelines (2002)
![Page 22: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/22.jpg)
Estimating BMR: Obesity
predicting BMR is very difficult (without measuring lean body mass)
adequacy of specific equations? (Ireton-Jones et al., 1992; Glynn et al., 1998)
• actual body weight + stress + activity = overestimate
access to indirect calorimetry is limited
![Page 23: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/23.jpg)
Determining energy requirements in obesity
• non stressed patients:– calculate as normal and - 400-1000kcal for decrease
in energy stores
• mild to moderately stress:– calculate as normal – omission of stress and activity avoids the adverse
effects of overfeeding
• severe stress– might be necessary to add a stress factor to BMR
• *monitoring essential eg blood glucose
![Page 24: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/24.jpg)
Estimating energy requirements
• The main components of energy expenditure are estimated:– BMR– Alteration in BMR due to disease process
(stress factors)– Activity– DIT
![Page 25: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/25.jpg)
Levels of evidence
1. a) Meta-analysesb) Systematic reviews of randomised controlled trials (RCTs)c) RCTs
2. a) Systematic reviews of case-control or cohort studiesb) Case-control or cohort studies
3. Non-analytic studies e.g. case studies4. Expert opinion(adapted from: Draft NICE Guidelines for Nutrition Support in Adults, 2005)
![Page 26: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/26.jpg)
Stress factors
timing of measurements over (hyperalimentation) vs. under-feeding changes in therapeutic interventions
e.g. improved wound care, anti-pyretics, sedation, control of ambient room temperature
err towards lower end of the range and monitor
![Page 27: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/27.jpg)
Stress factors
• unable to include a stress factor for every disease or condition
• many measured in far from ideal circumstances• limited by data available• may choose to underfeed in certain
circumstances• necessary to refer back to the literature• included a checklist of factors to look for when
reviewing papers
![Page 28: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/28.jpg)
Adverse effect of over-feeding
• excess carbohydrate:– difficulties controlling blood glucose– increased CO2 production– respiratory problems in vulnerable patients (eg
COPD/ ventilated)• swings in blood glucose increase mortality in
critically ill• aim not to exceed the glucose oxidation rate (4-7
mg glucose/ kg/ min)• long term excess carbohydrate can lead to
steatohepatosis or fatty liver (Elwyn DH, 1987).
![Page 29: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/29.jpg)
Estimating energy requirements
• The main components of energy expenditure are estimated:– BMR– Alteration in BMR due to disease process– Activity– DIT
![Page 30: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/30.jpg)
Total energy expenditure
BMR
Activity+ DIT
Activity+ DIT
Health Disease
BMR
![Page 31: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/31.jpg)
Activity factor
• energy expended during active movement of skeletal muscle
• approximately 20-40% of energy expenditure in free living individuals
• depends on duration and intensity of the exercise
• activity is less than 20% of the energy expenditure in hospitalised or institutionalised
• NB assumes normal muscle function
![Page 32: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/32.jpg)
Activity factor for activity: institutionalised patients combined
with DIT
Activity level Males and females
Bedbound immobile
Bedbound mobile/ sitting
Mobile on ward
+ 10%
+ 15 – 20%
+ 25%
![Page 33: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/33.jpg)
Activity factor:abnormal muscle function
• hospital patients likely to have higher activity levels:– abnormal neuro-muscular function e.g. brain
injury, Parkinson’s, cerebral palsy, motor neurone disease, and Huntington’s chorea
– prolonged active physiotherapy– effort involved in moving injured or painful
limbs
![Page 34: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/34.jpg)
Community patients
• free living individuals have higher energy expenditure due to physical activity
• nursing home and house bound patients ? similar activity levels to hospital patients
• for active patients in the community a PAL should be added
![Page 35: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/35.jpg)
Physical activity level (PAL) of adults
Non-occupational activity
occupational activity
light
M F
occupational activity
moderate
M F
occupational activity
mod/ heavy
M F
non active
m. active
very active
1.4 1.4
1.5 1.5
1.6 1.6
1.6 1.5
1.7 1.6
1.8 1.7
1.7 1.5
1.8 1.6
1.9 1.7
![Page 36: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/36.jpg)
Estimating energy requirements
• The main components of energy expenditure are estimated:– BMR– Alteration in BMR due to disease process– Activity– DIT
![Page 37: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/37.jpg)
Diet-induced thermogenesis
Continuous infusion of enteral feed and parenteral nutrition do not significantly increase REE
Bolus feeding increases REE by ~ 5% Mixed meal increases REE ~ 10 % PALs include DIT (COMA, 1991)
guidelines include combined factor for activity and DIT
![Page 38: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/38.jpg)
Estimating requirements: sources of error
• prediction equation for BMR
• stress factor:– degree of stress inaccurately assessed– poor evidence to support stress factor used
• activity level inaccurately assessed or poorly understood
• DIT varies by 10% depending on feeding method
![Page 39: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/39.jpg)
Sources of error: inaccurate weight
• Inaccurately measured weight – estimated weight– inaccurate scales– patient had their feet on the floor (chair
scales)– patient was fluid overloaded ( 20% of
hospital patients)– amputees
![Page 40: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/40.jpg)
![Page 41: Current Evidence for Estimating Energy Requirements Clare Soulsby, Research Dietitian](https://reader036.vdocuments.us/reader036/viewer/2022062318/5516233255034694308b5aa0/html5/thumbnails/41.jpg)
Conclusions
Estimated requirements are only a starting point- set realistic goals of treatment for each patient- monitor and amend as patient’s condition changes
Review and criticise the literature regularly- be aware of gaps in the evidence- understand the limitations of guidelines- check applicability to your patients
Contribute to research and audit projects