Transcript Smoking Cessation and Body Weight

Energy and Protein
Requirements
Robert Kushner, MD
Northwestern University Feinberg School of Medicine
[email protected]
Starvation and
Protein-Energy Malnutrition:
Importance of Lean Body Mass
Health 100%
Decreased muscle mass: skeletal, cardiac
Decreased visceral proteins: albumin
Impaired immune response
LEAN BODY MASS
Impaired wound healing
Impaired organ function
Nitrogen Death
70%
Starvation and
Protein-Energy Malnutrition:
Clinical Implications
Fatigue, general weakness
Decreased
muscle mass
Lack of initiative
Bedridden
Decreased visceral proteins
Apathy
Impaired wound healing
Organ failure
Complete Exhaustion
“Normal”
“Catabolic Patients”
5 weeks
10 weeks
Acceleration of Malnutrition
due to Metabolic Stress
• Energy expenditure is increased
• tachycardia, fever, increased RMR
• Catabolism of muscle occurs due to
increased protein needs
– stress hormones stimulated
– cytokines released
• weakness, loss of muscle tissue,
increased urinary urea nitrogen
Mediators of the
Metabolic Response
• Cytokines
– IL-1, IL-6, TNF-
• Glucagon, Epinephrine, Norepinephrine
• Corticosteroids
• Eicosanoids
– Leukotrienes, Thromboxanes
• Growth Factors
– IGF-1
“Fuels” Energy substrates
• Free fatty acids
– Triglycerides
• Diet
• Adipose tissue
• Glucose
– Starches and sugars
• Diet
• Glycogen
• Amino acids
– Protein
• Diet
• Tissue
Energy Reserves of a 70 kg man,
expressed in kcal
Protein*
24,000
Adipose tissue
135,000
Liver glycogen
280
Muscle glycogen
480
*Body protein, which can readily be
converted to glucose, is not stored for any
reason, since all proteins are functional
Relationship between Energy and Protein Requirements
(1.1 g pro/kg)
(1.3 g pro/kg)
Nitrogen equilibrium attained is at
near-energy equilibrium
Slope = 1.4 mg of N/kcal
Components of
Total Daily Energy Expenditure
TEF
RMR
ET
NEAT
PA
RMR=resting metabolic rate; TEF=thermic effect of feeding;
ET=exercise thermogenesis; NEAT=non-exercise thermogenesis
How Do we Estimate or Measure our
Patient’s Energy Requirements?
• Total energy expenditure = RMR + TEF + PA
• 3 common methods used:
– Estimate RMR, then use a stress and PA multiplier
– Measure RMR, then use a PA multiplier
– Use a simple estimate for all patients
RMR
TEF
PA
Estimating RMR
• Harris Benedict, 1919
– Men: RMR = 66.5 + (13.8 x weight) + (5 x height) – (6.8
x age)
– Women: RMR = 655.1 + (9.6 x weight) + (1.8 x height) –
(4.7 x age)
• Mifflin-St. Jeor, 1990
– Men: RMR = (10 x weight) + (6.26 x height) – (5 x age)
+5
– Women: RMR = (10 x weight) + (6.26 x height) – (5 x
age) – 161
• Institutes of Medicine (IOM)
• World Health Organization (WHO)
Estimating a Stress Factor
Estimating a Stress Factor
Energy Expenditure in
Hospitalized Patients
• 1256 patients in 19 studies
–
–
–
–
–
Postoperative (28%)
Trauma or sepsis (26%)
Cancer (18%)
Pulmonary disease (9%)
**Excluded individuals with fever (11%/C), burns (140% to
150%), and head injuries (120% to 145%)
• Mean stress (SD) factor was 113% (10.9) above
predicted by Harris Benedict equation
Miles JM. Mayo Clin Proc 2006;81:809
Potential energy
Principles of Indirect Calorimetry
Metabolic Coupling
Fuel
+ O2
Lost as heat
ATP
CO2
+ H2O
Captured
energy (40%)
ADP
Reality: multiple steps with multiple intermediates, but
this net reaction.
Principles of Indirect Calorimetry
V02
Assumptions of Indirect Calorimetry
• The gaseous input and exhaust products from the
metabolic combustion process (O2 and CO2) pass only
through the nose and mouth
– Chest tubes, air leaks
• O2 input is fixed and constant
– Nasal cannula, ventilator changes
• All nutrients are metabolized to the end products of CO2,
H2O and urea
– Renal failure, diabetic ketoacidosis
• Other causes of altered respiration, e.g., metabolic
alkalosis and acidosis, hyper- and hypoventilation, oxygen
debt, are not present
• Protein is assumed to contribute 12.5% of caloric
expenditure (Weir equation)
– Excessive protein breakdown, high protein diet
Estimated Energy
Requirements
Resting state
20-30 kcal/kg d
Uncomplicated
25-35 kcal/kg d
postoperative
Nutritionally depleted 30-40 kcal/ kg d
Hypermetabolic
(trauma, sepsis)
35-40 kcal/ kg d
Changes with age of mean energy and
protein requirements
Millward, D. J. J. Nutr. 2004;134:1588S-1596S
Nitrogen Balance, units
Protein Requirement
Feeding High Quality Protein
1
0
-1 0
-2
-3
-4
-5
-6
-7
-8
0.2
0.4
0.6
0.8
Average
Requirement
Protein Intake, gm/kg/d
1
Protein Requirements
• Estimated Average Requirement (EAR)
= 105 mg N/kg/d or 0.66 g/kg/d
• Recommended Dietary Allowance
(RDA) =
– x 2 SD (97.5% of population)
– 0.66 x (1 + 2 x 0.125) = 0.80 g/kg/d
• 70 kg male = 56 g/d
• 55 kg female = 46 g/d
Usually measured as nitrogen
1 g N = 6.25 g Protein
168 g pro (2.5 g/kg)
70 g pro (1.1 g/kg)
N Balance is Dependent on More than Energy
Measuring Protein (Nitrogen) Balance
• N balance evaluates adequacy of protein intake
relative to need
• N metabolism is dependent on both energy and
protein intake + adequate minerals
• N balance (g/d) = (protein intake/6.25) – (urinary
nitrogen [mostly urea] + fecal losses + obligatory
losses)
• Clinically, measure total urinary urea N (UUN) +
2-4 g for non-urea losses
Estimating Nitrogen Losses
Non-urea nitrogen losses
(open abdomen)
*Traditional method of estimating N balance = N intake – (24 hr UUN + 4)
Cheatham et al. Crit Care Med 2007;35:127
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Effect of Disease and Trauma
on Protein Requirements
2.5
2
1.5
1
0.5
0
Estimated Protein
Requirements
Resting state
0.8-1.0 g/kg d
Uncomplicated
postoperative
Depleted patients
1.0-1.3 g/kg d
Hypermetabolic
(trauma, sepsis)
1.5-2.0 g/kg d
1.3-1.7 g/kg d
Conclusion
• Adequate energy and protein must be
provided to prevent auto-cannibalism,
progressive malnutrition and poor clinical
outcomes
• Energy and protein balance are inter-related
• Requirements should be estimated and/or
measured for each patient