Dr. Elizabeth Weekes Department of Nutrition & Dietetics Guy’s & St. Thomas’ Hospitals NHS Foundation Trust Lond

1. Controversies in the determination of energy requirements Dr. Elizabeth Weekes Department of Nutrition & Dietetics Guy’s & St. Thomas’ Hospitals NHS Foundation Trust London

3. Controversies • 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?

4. Total Energy Expenditure DIT Activity BMR

5. Methods of estimating energy expenditure • 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

6. Prediction 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)

7. Basal 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

8. 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 = Resting Energy Expenditure (REE)

9. 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

10. MEE in healthy subjects Activity DIT Doubly-labelled water BMR Indirect calorimetry

11. MEE 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

12. MEE in disease Activity DIT BMR + Stress Indirect calorimetry

13. Controversies • 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?

14. Reviewing 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

15. Energy requirements in COPD • Schols et al. (1996) Age 61 (+ 6) years; BMI 23.5 (+ 4.2) kg/m2 REE < 105 % HB in 14 patients REE > 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 admission REE 113 (+ 14) % HB on discharge (REE > 110 % HB in 10 patients at discharge) 23 acute COPD patients admitted to hospital

16. Controversies • 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?

17. Estimating requirements in clinical practice (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

19. Metabolic response to injury

20. Assessing 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

21. 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

22. Estimating requirements in clinical practice (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

23. Physical activity • Assumes normal neuro-muscular function Review 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)

25. Physical 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

26. Estimating requirements in clinical practice (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)

27. Estimating requirements in clinical practice 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

28. If I feed my patient to estimated energy requirements will he/she do better than if 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?

29. 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 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