lizabeth Weekes tment of Nutrition & Dietetics & St. Thomas’ Hospitals NHS Foundation Trust n roversies in the determination of energ roversies in the determination of energ irements irements
Mar 28, 2015
Dr. Elizabeth WeekesDepartment of Nutrition & DieteticsGuy’s & St. Thomas’ Hospitals NHS Foundation TrustLondon
Controversies in the determination of energy Controversies in the determination of energy requirementsrequirements
ControversiesControversies
Is measured energy expenditure (MEE) always the most accurate way to determine energy requirements?
Is it valid to extrapolate results from a study population to an individual patient?
What should we do in clinical practice?
If I feed my patient to estimated energy requirements will he/she do better than if I don’t?
Total Energy ExpenditureTotal Energy Expenditure
BMR
DIT
Activity
Methods of estimating energy Methods of estimating energy expenditureexpenditure
Indirect calorimetry• Short-term measurements (up to 24 hours)• Hood/ventilator modes
Doubly-labelled water technique• Long-term measurements (several weeks)• Cost and technical considerations• Measures Total Energy Expenditure
Prediction equations + fudge factors
Prediction equationsPrediction equations
May over or under-estimate compared with measured energy expenditure (MEE)
Inadequately validated
Poor predictive value for individuals
Open to misinterpretation
(Cortes & Nelson, 1989; Malone, 2002; Reeves & Capra, 2003)
Basal metabolic rateBasal metabolic rate
Minimal intra-individual variation ~ 3%
Inter-individual variation ~ 10% depending on:- • proportions of body cell mass and metabolically active
organs and tissues• thyroid function• circadian rythms
Conditions essential for measuring Conditions essential for measuring BMRBMR
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 = Resting Energy Expenditure (REE)
Measured Energy Expenditure (MEE)Measured Energy Expenditure (MEE)
Measured in clinical setting by indirect calorimetry
(rarely available in UK hospitals)
Recommended in certain conditions e.g. liver disease, obesity, critical illness (ASPEN, 2002)
Needs to be measured correctly in order to provide valid and reliable data
MEE in healthy subjectsMEE in healthy subjects
BMR
DIT
Activity
Indirectcalorimetry
Doubly-labelledwater
MEE in clinical studiesMEE in clinical studies
Calibration
How long and how often to measure
Achieving a steady-state• Lying in bed, awake and aware• No social or physical interactions• Avoid haemodialysis and filtration
Patient/apparatus interface• Hood/canopy• Ventilated patients
MEE in diseaseMEE in disease
BMR +Stress
DIT
Activity
Indirectcalorimetry
ControversiesControversies
Is measured energy expenditure (MEE) always the most accurate way to determine energy requirements?
Is it valid to extrapolate results from a study population to an individual patient?
What should we do in clinical practice?
If I feed my patient to estimated energy requirements will he/she do better than if I don’t?
Reviewing the literatureReviewing the literature
Patient demography Sample size Diagnosis Severity of illness/injury and metabolic status Nutritional status Nutritional intake Temperature (room and patient) Therapeutic interventions e.g. ventilation, drugs Methodology
Energy requirements in COPDEnergy requirements in COPD
Schols et al. (1996)Age 61 (+ 6) years; BMI 23.5 (+ 4.2) kg/m2
REE < 105 % HB in 14 patientsREE > 120 % HB in 16 patients (weight-losing, FFM, CRP and acute phase proteins)30 stable COPD patients admitted to rehabilitation unit
Vermeeren et al., (1997)Age 63 (+ 8) years; BMI 23.0 (+ 3.2) kg/m2
REE 123 (+ 11) % HB on admissionREE 113 (+ 14) % HB on discharge(REE > 110 % HB in 10 patients at discharge) 23 acute COPD patients admitted to hospital
ControversiesControversies
Is measured energy expenditure (MEE) always the most accurate way to determine energy requirements?
Is it valid to extrapolate results from a study population to an individual patient?
What should we do in clinical practice?
If I feed my patient to estimated energy requirements will he/she do better than if I don’t?
Estimating requirements in clinical Estimating requirements in clinical practicepractice (I) (I)
Assess metabolic state• Is my patient metabolically stressed, recovering or
anabolic• Is there a risk of re-feeding syndrome?
Establish physical activity level• Is the patient sedated, bed-bound, mobile on ward, receiving
physiotherapy, at home
Determine goals of treatment• e.g. minimise losses, weight maintenance or weight change
Metabolic response to injuryMetabolic response to injury
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Time (hours)
Injury
Necrobiosis and death
24 48 96 120
Assessing metabolic stressAssessing metabolic stress
Stressed temperature urea white cell count C-reactive protein albumin insulin resistance• Oedema
N.B. Stress response may be blunted in immuno-compromised and elderly patients
Stress factorsStress 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
Estimating requirements in clinical Estimating requirements in clinical practicepractice (I) (I)
Assess metabolic state• Is my patient metabolically stressed, recovering or
anabolic• Is there a risk of re-feeding syndrome?
Establish physical activity level• Is the patient sedated, bed-bound, mobile on ward, receiving
physiotherapy, at home
Determine goals of treatment• e.g. minimise losses, weight maintenance or weight change
Physical activityPhysical activity
Assumes normal neuro-muscular functionReview literature for patients with abnormal function
e.g. brain injury, Parkinson’s disease, cerebral palsy, motor neurone disease and Huntington’s chorea
Prolonged and active physiotherapy
Increased effort of moving injured/painful limbs
Mechanical inefficiency e.g. COPD (Baarends et al., 1997)
Physical activityPhysical activity
Free living individuals have higher energy expenditure due to physical activity
Nursing home and house-bound patients may have similar activity levels to hospitalised patients
For active patients in the community a PAL should be added
Estimating requirements in clinical Estimating requirements in clinical practicepractice (I) (I)
Assess metabolic state• Is my patient metabolically stressed, recovering or
anabolic• Is there a risk of re-feeding syndrome?
Establish physical activity level• Is the patient sedated, bed-bound, mobile on ward, receiving
physiotherapy, at home
Determine goals of treatment• Should I aim to minimise losses, maintain weight or achieve
weight change (loss or gain)
Estimating requirements in clinical Estimating requirements in clinical practice IIpractice II
Be aware of the literature on energy requirements in your patient group (and any gaps in the evidence)
Compare your patient with available literature and either assign relevant stress factor OR adjust for weight change
Monitor, review and amend requirements as clinical condition, physical activity and nutritional goals change
If I feed my patient to estimated energy If I feed my patient to estimated energy requirements will he/she do better than if requirements will he/she do better than if
I don’t?I don’t?
Over-feeding is not good
(Askanazi et al., 1980; Lowry & Brenman, 1979; Kirkpatrick et al., 1981)
Is under-feeding always bad?
Should we start everyone on 1500 kcal/day?
ConclusionsConclusions
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 critically appraise the literature• Be aware of gaps in the evidence• Understand the limitations of guidelines• Check applicability to your patients
Contribute to research and audit projects