assessment of energy needs david l. gee, phd professor of food science and nutrition central...
Post on 20-Dec-2015
217 views
TRANSCRIPT
![Page 1: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/1.jpg)
Assessment of Energy Needs
David L. Gee, PhDProfessor of Food Science and NutritionCentral Washington University
![Page 2: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/2.jpg)
Reasons to assess energy needs• Energy needs are highly variable• Prevent underfeeding
– decrease organ mass and function– impaired wound healing– impaired immune response
• Prevent overfeeding– excessive CO2 production
• Respiratory acidosis
– Hyperglycemia and insulin resistance– fluid retention and fat gain (fatty liver)
![Page 3: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/3.jpg)
Estimation of Resting Energy Expenditure (REE) with Prediction
Equations• Harris-Benedict Equation (1919)
– based on gender, weight, height, age
• WHO Equations (1982)– based on gender, weight, age
• Errors in estimation:– Standard deviation = 10%
– 95% confidence interval = 20%
![Page 4: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/4.jpg)
Validation of Several Established Equations for Resting Metabolic Rate in
Obese and Nonobese People.Frankenfield et al., JADA 103:1152(2003)
• 130 healthy adults (BMI=18.8-96.8)– 98% white
• Compared equations to indirect calorimetry– Harris-Benedict– Adjusted Harris-Benedict (25% of excess wt)– Owen (1986)– Mifflin (1990)
• Men: kcal/d=5+10(wt)-6.25(ht)-5(age)• Women: kcal/d=-161+10(wt)+6.25(ht)-5(age)• Wt=kg, ht=cm,age=yrs
![Page 5: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/5.jpg)
![Page 6: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/6.jpg)
![Page 7: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/7.jpg)
Accurate Determination of Energy Needs in Hospitalized
Patients.Boullata et al., JADA 107:-393-401 (2007)
• 395 hospitalized patients• Compared prediction equations against
measured REE– Harris-Benedict, Mifflin, 6 others
• Conclusions:– Most accurate was Harris-Benedict multiplied by
1.1, but only 62% were within 10% of measured REE
– “No equation accurately predicted REE in most hospitalized patients … only indirect calorimetry will provide accurate assessment of energy needs.”
![Page 8: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/8.jpg)
Why prediction equations fail…• Equations based on gender, height,
weight and age explain ~ 80% of individual variation in REE
• Sources of other variations– Mass of various tissues
• Visceral tissues 10x more active than muscle tissue at rest and 100x more active than adipose
• Knowing body composition based on 2-component or 4-component models still inadequate
![Page 9: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/9.jpg)
Estimation of Total Energy Expenditure is even less
accurate• TEE = REE + Activity + TEF + Injury factors
• estimations of – activity
– TEF
– injury factors
• are crude estimates
![Page 10: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/10.jpg)
Indirect Calorimetry
• Estimation of energy expenditure based on respiratory gases– oxygen consumed
– carbon dioxide produced
• Nutrient + O2 -> CO2 + H2O + energy
• Metabolic Carts
• Hand-held Indirect Calorimeters
![Page 11: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/11.jpg)
Oxidation of glucose• Glucose + 6O2 -> 6CO2 + 6H2O + 673Cal/mol
• 673/6 = 112 Cal/mol O2
• Respiratory Quotient (RQ) = Respiratory Exchange Ratio (RER) = CO2/O2
• RQCHO = 6/6 = 1.0
![Page 12: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/12.jpg)
Oxidation of Fat• Palmitate + 23O2 -> 16CO2 + 16H2O + 2398Cal/mol
• 2398/23 = 104 Cal/mol O2
• RQ = 16/23 = 0.7
![Page 13: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/13.jpg)
Oxidation of Amino Acids• RQ for amino acids and the energy produced per
mol of O2 varies for each amino acid
• RQ for average protein is 0.85• Contribution of protein oxidation is ignored
because:– small compared to fat and glucose
– RQ at rest is typically close to 0.85
– protein oxidation during short-term exercise is very small compared to fat and glucose
– To measure protein oxidation, one needs to collect 24hr urine to measure total urea production
![Page 14: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/14.jpg)
RQ (RER) Tables
• RQ or RER can be used to:
– Determine the calories burned per •liter of oxygen consumed or•Liter of carbon dioxide produced
– Determine the % of calories produced by burning fats and carbohydrates
![Page 15: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/15.jpg)
Indirect Calorimetry Calculations
Method I (rough estimate)
• Approximately 5.0 Cal/l O2
• l O2/min x 5.0 Cal/lO2 = Cal/min• example:
– VO2 = volume of O2 consumed/min = 0.2 l/min
– then 0.2 x 5 = 1 Cal/min – if REE, then 1 Cal/min x 1440 min/d = 1440Cal/d
![Page 16: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/16.jpg)
Indirect Calorimetry Calculations
Method 2 (not so rough estimate)
• More accurately: 4.8 Cal/l O2
• Example– if: VO2 = 0.2 l/min
– then: 0.2 x 4.8 = 0.96 Cal/min
– if REE, then 0.96 x 1440 = 1382 Cal/d
![Page 17: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/17.jpg)
Indirect Calorimetry CalculationsMethod 3 - using total RQ• if VO2 = 0.2 l/min and VCO2 = 0.17
l/min• then RQ = 0.17 / 0.2 = 0.85
• if RQ = 0.85, then 4.862 Cal/lO2
• 0.2 x 4.862 = 0.97 Cal/min• 0.97 x 1440 = 1400 Cal/day
![Page 18: Assessment of Energy Needs David L. Gee, PhD Professor of Food Science and Nutrition Central Washington University](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d4a5503460f94a27633/html5/thumbnails/18.jpg)
Determination of VO2 and VCO2
• Go to the Word document on Indirect Calormetry Calculations