Measuring versus Estimating Resting Metabolic Rate

Transcription

1 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) Measuring versus Estimating Resting Metabolic Rate Identifying the most accurate information for an individual's Resting Metabolic Rate (RMR) is critical because RMR accounts for the majority of an individual s energy expenditure (EE), and the basis upon which stress and activity factors are multiplied. How Is RMR Determined? Two approaches have been used to determine RMR: To assess the caloric needs of an individual, dietetics professionals have traditionally used prediction equations to estimate the resting metabolic rate (RMR)a and added a stress and/or activity factor. An alternative to the prediction equations is to measure RMR by indirect calorimetry (IC). Which method is appropriate in a given situation? Using Clinical Judgement Clinical judgment is needed to determine when the RMR will be a critical element of the nutrition care plan and likely to impact significantly important patient/client outcomes. Regardless of the method to determine RMR, estimated or measured, careful clinical judgment is essential to evaluate the RMR value and its application in an individual s nutrition care and outcomes. Scientific Judgement as an Aid to Clinical Judgement This appendix reviews the scientific evidence related to predicting and measuring RMR and provides insight into applying both methods, including a decision making flowchart, supporting tables, and practitioner and patient instructions for measuring RMR. Evidence analysis Estimating RMR with prediction equations Evidence analysis Measuring RMR with indirect calorimetry (IC) Sponsor: Funding for the Energy Expenditure: Measurement versus Estimation Evidence Analysis Project was provided by HealtheTech ADA acknowledges the generous sponsors who have provided support for Evidence Analysis Projects. Note: ADA maintains full control over the content and process of ALL evidence analysis projects including the selection of topics, evaluation of research, assignment of grades, and development of recommendations.

2 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Evidence analysis: Estimating RMR with prediction equations Estimating RMR with Prediction Equations: What Does the Evidence Tell Us? The ADA evaluated four common RMR prediction equations using its rigorous Evidence Analysis Process (which includes a systematic review of the literature), to assess their ability to accurately predict RMR within +/- 10% of measured RMR in various healthy[1] populations: 1. non-obese 2. obese 3. various ethnic groups 4. older age groups (1) Detail on Equations and Grades Table 1 details the equations, including those developed by Harris-Benedict, Mifflin-St. Jeor, Owen, and the World Health Organization/Food & Agricultural Organization/United Nations University (WHO/FAO/UNU)[2]. Each article that met the sorting criteria was reviewed and summarized. Based upon this analysis, expert panel members developed conclusion statements, and grades were assigned to communicate the strength of the evidence. Table 2 defines the grades the ADA uses to determine the strength of the evidence. What Does the Research Tell Us? Despite widespread use of the Harris-Benedict equation, the Mifflin-St. Jeor equation performed the best when predicting RMR in non-obese and obese populations, years of age (1). In other populations: Older adults: In older adults (60-82 yr) across all weight classifications and with all of the equations, error ranges were large (maximum underestimations up to 31% to maximum overestimations of 12%) and none of the equations sufficiently evaluated individuals >80 years of age. Non-white racial populations: The evidence analysis revealed that none of the equations have been adequately studied for their applicability to U.S.-residing racial and ethnic populations. Underweight adults: The analysis did not attempt to assess the accuracy of the equations in underweight populations (BMI< 18.5). It may be advised to measure RMR using indirect calorimetry in older adults, individuals of non-white race, and underweight adults to obtain more accurate RMR information. Table 3 provides more complete findings from the evidence analysis (1). The full results from the evidence analysis of healthy individuals are available through the ADA Evidence Analysis Library which can be accessed through The ADA has plans for a future evidence analysis project for determining RMR in ill individuals. [1] Healthy individuals represent adults who do not have illnesses directly affecting RMR (e.g., diabetes mellitus, hypothyroidism, heart failure) or take medications known to affect RMR, with studies using individual telephone screenings, medical examinations, health surveys or self-report to establish. While health is relative, physiological changes with multiple interactions (such as age, multiple chronic and acute occurrences), the current predictive equation errors were developed from volunteer subjects who met the above mentioned criteria and/or who perceived their physical condition as healthy. [2] The Carol Ireton-Jones equation was not included in the evidence analysis for estimating RMR since it is used for patients in the critical care setting rather than in healthy individuals as defined above. It will be examined as part of a future evidence analysis. Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

3 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Evidence analysis: Measuring RMR with indirect calorimetry (IC) Measuring RMR with Indirect Calorimetry: What Does the Evidence Tell Us? Measuring resting metabolic rate with indirect calorimetry is a way to improve the accuracy of the RMR value as compared to the common prediction equations. However, IC is not free from error. Another evidence analysis project conducted by the ADA examined factors that may impact indirect calorimetry measurements in healthy and ill populations. Three broad areas were evaluated for their impact upon IC: 1. the procedures (e.g., length of measurement, type of equipment) 2. timing (e.g., physical activity, food ingestion) 3. intra-subject variability (e.g., circulatory hormones, medication use) (1). Summary of the Evidence Table 4 summarizes the conclusion statements for each of the factors evaluated. Table 5 includes the medications examined as part of the evidence analysis. The full description of the evidence analyzed is provided in the Evidence Analysis Library which can be accessed through Additional Factors To Consider in Indirect Calorimetry Additional factors for consideration when measuring RMR include: equipment malfunction a patient/client s ability to tolerate and comply with IC measurement practitioner s access to and competency in using IC Yet with these considerations, IC can provide a more accurate RMR value if appropriate conditions exist and all of the factors potentially impacting RMR are taken into consideration. Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

4 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Application Application of the ADA Indirect Calorimetry Evidence Analysis to Practice Four resources are available to help apply the best research on indirect calorimetry to dietetic practice: Flowchart and Instructions The hyperlinked flowchart and instructions highlight the key decisions points when using RMR in the nutrition care process (2). Practitioner Instructions These instructions apply to most patient/client situations in practice. Patient Instructions Instructions that can be provided to a patient/client prior to measuring RMR. Information on Different Types of Indirect Calorimeters There are times when specific types of collection units (i.e., a face mask, mouth piece with nose clip, or canopy) are not reliable in obtaining a RMR. For example, men with beards or frail older adults with skinny jaws have a higher risk of gas leaking around the face mask. A sample list of desirable features of indirect calorimeters can be found in Table 6 (3). Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

5 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Flowchart: Obtaining, interpreting, and reassessing the RMR value Flowchart for Carrying Out Indirect Calorimetry Measurements Below are the instructions for using the flowchart. To see the flowchart itself, click here. Three action steps appear on the flowchart: Step one is to determine if the RMR should be estimated or measured. Because unexpected RMR results can occur, Step two is to use critical thinking skills to evaluate the RMR. Step three is to determine when the RMR should be re-evaluated. The flow chart illustrates these decision points and factors to consider when the RMR is part of the nutrition care process. Step One: Estimating versus measuring RMR A number of factors should be evaluated when a dietetics professional considers whether to estimate or measure RMR. The common RMR prediction equations can be easily used without any equipment. However, significant limitations do exist. New, portable, and cost-effective indirect calorimeters offer professionals an alternative to the prediction equations. Moreover, indirect calorimetry may be indicated when RMR measurement precision is important to the outcomes (e.g. a client with unexpected weight loss or medically-dangerous weight gain), the individual is from a racial or ethnic population, or > 80 years of age, measurement of RMR by. Individuals not eligible for indirect calorimetry measurement include those who: Require nasal oxygen supplementation Complain of upper respiratory infection symptoms Have a nasal or oral tube in place Also, the new, portable indirect calorimeters cannot be used with patients requiring mechanical ventilation. A metabolic cart must be used to measure RMR. Step Two: Factors to consider when measuring RMR Whether RMR is estimated or measured, good clinical judgment is needed to evaluate any RMR value when used in the nutrition care process (2). Critical thinking, as part of a patient/client s nutrition care, includes integrating and evaluating objective measurements and practice experience. It is necessary to interpret RMR values since different factors may affect prediction and measurement (Table 4) medications can affect measurement (Table 5) In both cases, unexpected RMR results can occur, and proper interpretation of indirect calorimetry results requires critical thinking. Step Three: Reassessing the RMR Finally, as with any nutrition care plan, individual monitoring and evaluation for the patient/client s response to the intervention is needed. Re-assessment of RMR is warranted when: Weight remains unchanged or the change is contrary to the desired loss or gain (this excludes changes in weight due to fluid status) Medication affecting RMR has been initiated or discontinued (refer to Table 5 for more information regarding medications) Change in condition that is likely to affect RMR occurs: potentially decreasing RMR for example, significant weight loss, improvement in medical status (e.g., recovery from trauma, head injury, surgery) potentially increasing RMR for example, fever, infection, surgery, wounds, initiation of rigorous therapy regimen (e.g. rehabilitation), significant increase in lean body mass View the flowchart graphic to see how these steps fit into the larger decision-making framework. Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

6 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Flowchart: Obtaining, interpreting, and reassessing the RMR value > Flowchart for Using Indirect Calorimetry Flowchart for Obtaining, Interpreting and Reassessing the RMR Value The reasons to estimate or measure RMR vary among patients/clients and the decision-making process requires sound clinical judgment. Factors in estimating or measuring RMR include: the degree to which RMR impacts the primary outcome (e.g. trauma patient receiving enteral nutrition versus a client of appropriate body weight with elevated cholesterol), the patient/client s ethnicity age ability to tolerate and comply with indirect calorimetry measurement Another consideration is that practitioners may not have access to or the training needed for indirect calorimetry. Therefore, step one is to determine if the RMR should be estimated or measured. Because unexpected RMR results can occur, step two is to use critical thinking skills to evaluate the RMR. Step three is to determine when the RMR should be re-evaluated. Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

7 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Practitioner Instructions for Measuring RMR Practitioner Instructions for Measuring RMR The instructions below apply to most patient/client situations in practice. When the patient/client consents to the IC measurement: Explain the measurement procedure and answer any questions. Review and/or modify the patient/client instructions. Change or add any additional guidelines, as appropriate, based upon the patient/client s situation and the IC manufacturer s guidelines. In Preparation for the Measurement It is recommended that the patient/client do the following to prepare for indirect calorimetry measurement: Fast overnight or for at least five (5) hours prior to RMR measurement. If a five (5) hour fast would create medical risks, then a four (4) hour fast could be adequate if a small meal (i.e., 400 kcals or less) is consumed. If a very large meal (>900 kcals) is consumed prior to measurement, a six (6) hour or longer fast is recommended. Refrain from exercise the day before and the day of the measurement or for at least two (2) hours after light aerobic exercise. With higher intensity exercise of longer duration, a rest period of 24 hours is probably acceptable, but 48 hours is preferable. Refrain from nicotine or alcohol use for at least two (2) hours prior to the measurement. Detail the medications, herbs, vitamins, minerals, or other supplements he/she takes for further consideration after the measurement is obtained. The Day of the Indirect Calorimetry Measurement On the day of the indirect calorimetry measurement you should: Review the device instructions provided by the manufacturer to ensure compliance with all recommended guidelines. 1. Calibrate the machine according to manufacturer s instructions. The equipment must be operated by a trained individual. A system to demonstrate an individual s current competence in the use and care of IC equipment must be in place and meet the defined expectations of an organization such as the Joint Commission on Accreditation of Healthcare Organizations. 2. Confirm that no foods or fluids containing calories have been consumed for at least five (5) hours prior to the measurement. Provide a minute rest period for the patient/client prior to the measurement. At this time, review the measurement procedure and equipment and answer any questions. Determine a position for the patient/client during the measurement: 1. The truest and most reproducible resting metabolic rate measurement will be obtained in a lying position. The upper body can be inclined slightly (less than 30 degrees) based on patient comfort. 2. The next best alternative posture for measurement of metabolic rate is semi-recumbent, such as would be achieved with a reclining chair. The resulting measurement may be higher than true resting, but not significantly so. 3. The third best posture is sitting upright. The resulting measurement is likely to be higher than true resting, and in any given individual can be significantly higher than resting. Provide a quiet environment. Conduct one 10-minute measurement (discarding the first five minutes). This time frame should be sufficient for an accurate reading. If steady state is not achieved, consider remeasuring or using an alternative method for establishing a RMR. Ensure that no air leaks exist during the measurement. Comparable measures can be achieved with either a face mask, mouthpiece with nose clips, or canopy. Explain the measured RMRand its relationship to overall daily energy expenditure to the patient/client. Critically assess the value of RMR as part of the nutrition assessment (e.g., usual dietary intake and physical activity). Document RMR, the intervention initiated, and the monitoring plan to assess the outcomes. Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

8 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Patient instructions for measuring RMR Patient/Client Instructions: Measuring Your Resting Metabolism The most accurate way to assess your nutritional needs is to measure your resting metabolism or the number of calories you burn each day to maintain your normal body functions, such as heart rate, breathing, and brain activity. This is considered your resting metabolic rate and is done by measuring the amount of oxygen you consume (breathe in) and the amount of carbon dioxide you expel (breathe out). Factors for your lifestyle and exercise pattern will be considered along with your resting calorie needs to determine the best approach to your nutrition care. Your appointment is at. The following suggestions are recommended to optimize the results of the measurement. Your dietetics professional will advise you if these instructions need to be altered based upon your individual situation: Do not eat or drink anything (except water) after midnight prior to the measurement. If your measurement is not scheduled in the morning, do not eat or drink anything (except water) for at least five (5) hours before your measurement. Do not exercise the day before or the day of the measurement. Do not smoke or use nicotine (e.g., gum, patches) for at least two (2) hours before your appointment. Continue taking your medications as prescribed by your physician, advising your dietetics professional of each medication and any herbs, vitamins, minerals, or other supplements that you are taking. Plan to sit quietly for approximately 20 minutes prior to the measurement. One measurement is typically taken, although a second measurement may be needed. Depending on the equipment used, you may experience slight discomfort during the measurement (for example, if a nose clip is used, this closes both nostrils and requires that you breathe in and out through your mouth). Further information about the equipment being used will be described by your dietetics professional. Once your measurement is complete, your dietetics professional will interpret and may use the results as part of your nutrition care plan. Homepage of Appendix: Measuring versus Estimating Resting Metabolic Rate

9 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Tables > Table 6. Desirable features of an indirect calorimeter Table 6. Desirable Features of an Indirect Calorimeter (3) Safety features Alarm systems are reliable, include maximum and minimum limits, and limits can be altered Alarm signals are easily distinguishable from other alarms Equipment is electronically grounded Equipment is sturdy and durable Does not increase breathing resistance Ease of use Easy to operate Easy to clean Easy to assemble/set up Interfaces with existing ventilators Requires minimal warm-up time Portable Has storage space for supplies Has variable collection capabilities Autocalibrates Has computer capability Has software flexibility Can window out extraneous data Can modify reports/graphs Data entry and retrieval Display graphics Accuracy, precision, reliability Equipment is accurate, precise and reliable System operates without malfunctioning Alarms are reliable and consistent Durability Can be transported easily Can withstand heavy use Can be cleaned/washed easily and effectively Service/maintenance Company service agreement In-service training A toll-free number for answering questions Knowledgeable people answering the telephones Supplies are reasonably priced

10 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Tables > Table 1. Predictive equations for resting metabolic rate in kcal/day Table 1: Predictive Equations for Resting Metabolic Rate (RMR) in kcal/day All equations use weight in kilograms (kg), height in centimeters (cm) except the WHO/FAO/UNU equation that uses height in meters (m). Mifflin-St Jeor (4) Men: RMR = 9.99 X weight X height 4.92 X age + 5 Women: RMR = 9.99 X weight X height 4.92 X age 161 Harris Benedict (5) Owen (6,7) Men: RMR = X weight X height 6.75 X age Women: RMR = X weight X height 4.67 X age Men: RMR = X weight Women: RMR = X weight WHO/FAO/UNU (8) Weight only: Age (yr) Men RMR = 15.3 X weight RMR = 11.6 X weight >60 RMR = 13.5 X weight Women RMR = 14.7 X weight RMR = 8.7 X weight >60 RMR = 10.5 X weight Weight and height (m): Age (yr) Men RMR = 15.4 X weight 27 X height RMR = 11.3 X weight + 16 X height >60 RMR = 8.8 X weight X height 1071 Women RMR = 13.3 X weight X height RMR = 8.7 X weight 25 X height >60 RMR = 9.2 X weight X height 302

11 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Tables > Table 2. Grade Definitions, Strength of the evidence Table 2: Grade Definitions-Strength of the Evidence for a Conclusion/Recommendation (1) Grade I: Good The evidence consists of results from studies of strong design for answering the question addressed. The results are both clinically important and consistent with minor exceptions at most. The results are free of serious doubts about generalizability, bias, and flaws in research design. Studies with negative results have sufficiently large sample sizes to have adequate statistical power. Grade : Fair The evidence consists of results from studies of strong design answering the question addressed, but there is uncertainty attached to the conclusion because of inconsistencies among the results from different studies or because of doubts about generalizability, bias, research design flaws, or adequacy of sample size. Alternatively, the evidence consists solely of results from weaker designs for the questions addressed, but the results have been confirmed in separate studies and are consistent with minor exceptions at most. Grade I: Limited The evidence consists of results from a limited number of studies of weak design for answering the questions addressed. Evidence from studies of strong design is either unavailable because no studies of strong design have been done or because the studies that have been done are inconclusive due to lack of generalizability, bias, design flaws, or inadequate sample sizes. Grade IV: Expert Opinion Only The support of the conclusion consists solely of the statement of informed medical commentators based on their clinical experience, unsubstantiated by the results of any research studies. Grade V: Not Assignable There is no evidence available that directly supports or refutes the conclusion. Adapted from: Greer N, Mosser G, Logan G, Wagstrom Halaas G. A practical approach to evidence grading. Jt Comm. J Qual Improv. 2000; 26:

12 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Tables > Table 3. Conclusion statements, Accuracy of RMR estimations Table 3: Conclusion Statements Accuracy of Resting Metabolic Rate (RMR) Estimations (1) Equationa Non-Obese (20-82 y) (BMI kg/m2)b Obese (20-82 y) (BMI > 30 kg/m2) Older Adults (60-82 y) Non-Obese and Obese Mifflin- St. Jeor Harris-Benedict (Actual Body Weight) Harris-Benedict (Adjusted Body Weight)d 82% of estimates are accurate; errors evenly distributed between underand overestimation Maximal underestimations by 18% to overestimations by 15% (Grade )c 45-81% of estimates are accurate; errors tend to be overestimates Maximal underestimation by 23% to overestimation by 42% (Grade I) Not applicable 70 % of estimates are accurate; errors tend to be underestimates Maximal underestimations by 20% to overestimations by 15% (Grade ) 38-64% of estimates are accurate; errors tend to be overestimates Maximal underestimations by 35% to overestimations by 57% (Grade I) 26% of estimates are accurate; errors tend to be underestimates Maximal underestimation by 42% to overestimation by 25% (Grade I) Accuracy within 10% not available Underestimations by 18% to overestimations by 5% in men; and underestimations by 31% to overestimations by 7% in women (Grade ) Accuracy within 10% not available Underestimations by 19% to overestimations by 9% in men; and underestimations by 27% to overestimation by 12% in women (Grade I) Individual prediction accuracy using adjusted body weight is not reported for older adults in any of the evaluated studies. Owen WHO/FAO/UNU 73% of estimates are accurate; errors tend to be underestimates Maximal underestimation by 24% to overestimation by 28% (Grade ) Individual prediction accuracy is not reported for non-obese adults in any of the evaluated studies. 51% of estimates are accurate; errors tend to be underestimates Maximal underestimation by 37% to overestimation by 15% (Grade ) Individual prediction accuracy is not reported for obese adults in any of the evaluated studies. Accuracy within 10% not available There is no individual error range for men. In Caucasian women, maximal underestimation by 27% to overestimation by 12% (Grade I) Accuracy within 10% not available Maximal underestimation by 17% to overestimation by 7% in men. Maximal underestimation by 8% to overestimation by 12% in women (Grade I) athe formulas are listed with the most accurate formula at the top of the table. bnon-obese includes normal weight and overweight individuals based on BMI screening criteria. cthe Grade refers to the strength of the evidence supporting the statement made about the accuracy of the formula NOT TO THE ACCURACY ITSELF. For Example a Grade I for the Harris-Benedict using adjusted body weight for obese/overweight means that the evidence is GOOD that we know that only 26% of the estimates are accurate (within + or 10% of the measured number). However the Grade for Mifflin St-Jeor indicates that we have FAIR evidence to state that 70% of the estimates are accurate (within + or 10%). The Mifflin St Jeor appears to be a better formula than the Harris Benedict even though there aren t as many confirmatory research studies published. dabw = [(actual body weight ideal weight) X 0.25] + ideal weight

13 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Tables > Table 4. Evidence Analysis of IC, Factors for Consideration Table 4: Considerations for Measurement in Indirect Calorimetry, Results from Evidence Analysis Below are three tables that contain summaries from the evidence analysis of the important considerations for accurate indirect calorimetry measurement: 1. Considerations before measurement (Table 4.1) 2. Considerations during measurement (Table 4.2) 3. Considerations after measurement (Table 4.3) Table 4.1: Considerations Before Measurement Evidence Analysis Question Conclusion Statement Healthy Adults Adult Patients Institutionalized (transitional care, sub-acute) Evidence Grade Acute/ Trauma Critically ill/ventilated Ethnic Populations Comments DIETARY INTAKE What are the effects (defined as peak magnitude and duration) of meals on resting metabolic rates in healthy non-obese adults and special adult populations (i.e., obese and older adults)? Overall Conclusion Statement In most individuals, a fast of at least 5 hours prior to RMR measurement is preferred to reduce any impact of diet-induced thermogenesis, which is generally 7-9% of kcal consumed. However, if a 5-hour fast would create medical risks (e.g., diabetes), then a fast of at least 4 hours prior to a RMR measurement could be adequate to reduce any impact of diet induced thermogenesis if a small meal (i.e., 400 kcals or less) is consumed. If a very large meal (>900 kcal) is consumed within 5 hours of a RMR measurement, then a longer time (at least 6 hours) is recommended to reduce diet-induced thermogenesis to clinically insignificant levels (<100kcals/day). CAFFEINE What is the acute effect of administration or changes in chemical use of caffeine and tea and herbal or dietary stimulants (including ephedra) on RMR? *Ephedra examined but banned from sale by FDA in April Caffeine (acute): Available evidence does not permit conclusions on a dose-response effect of caffeine. Special Populations (Smokers): 6 to 10% increase in RMR above baseline over 30 to 180 minutes with concurrent use of caffeine and nicotine. Chronic Effect of Caffeine: Insignificant increase in RMR in men with a lower dose of caffeine. 8% in RMR in lean (mean BMI 24 +/- 1) Swiss females as compared to a 5% increase in age-matched obese individuals (mean BMI 28 +/- 0.9). 7-oxo-DHEA (e.g. 7-keto-Naturalean): No studies reporting short-term effects and no significant difference from baseline to 8 weeks in 7-oxo-DHEA vs. placebo. I IV IV SMOKING Do administration or changes in chemical use of nicotine have an effect on RMR? Acute Thermic Effect (males): RMR increased 4-9% in first min. Elevated group mean RMR remained 2 hours post-nicotine exposure. No data are available to indicate duration of chronic thermic effect of nicotine on RMR >8 and < 24 hours.

14 Acute Thermic Effect (females): Increase in RMR of 7.5% at 60 min and 5.7% at 160 mins in one study with return to at or below baseline min after nicotine. IV Smoking cessation: RMR increase of 63.2 and 54.3 kcals/d two weeks after nicotine cessation in black and white individuals respectively. IV ALCOHOL Do administration or changes in chemical use of alcohol have an effect on RMR? PHYSICAL ACTIVITY What are the acute effects on RMR following physical activity in healthy adults and how long does it take for a post-exercise RMR measure to return to pre-exercise RMR? Acute thermic effects: 4-6% increase of RMR over 95 min following gm of alcohol. Chronic thermic effects: RMR elevated 26% in middle-aged alcoholics but decreased to similar levels as non-alcoholic controls with 14 days of abstention. Alcohol ingestion with food: No effect is consistently supported. Overall Conclusion Statement If individuals have performed low to moderate intensity exercise (i.e., walking, jogging, cycling, or weight lifting) for 30 minutes or less, a rest period of 2 hours is needed prior to RMR measurement. If aerobic or resistance exercise is performed at higher exercise intensities for longer durations, a rest period of 9 to 24 hours is probably acceptable, but 48 hours is preferable, prior to an RMR measurement to avoid measuring activity energy expenditure. I I I MEDICATIONS What are the effects of medications on RMR? Summary presented in Table 5. Back to top Table 4.2: Considerations During Measurement Evidence Analysis Question Conclusion Statement Healthy Adults Adult Patients Institutionalized (transitional care, sub-acute) Evidence Grade Acute/ Trauma Critically ill/ventilated Ethnic Populations Comments NUMBER OF MEASURES One measurement is sufficient. How many times within a 24-hour period does the individual need to be measured? One measurement is sufficient if steady state (SS) is achieved. In individuals unable to achieve SS or tolerate measurement conditions, two or more nonconsecutive single measurements may improve value. I TEST MEASUREMENT INTERVAL What is an acceptable energy measurement interval to reflect RMR? 10 minute measurement under steady state conditions (discarding the first 5 minutes of measurement). 20 minute measurement may be sufficient. I IV I IV

15 10 minute measurement (discarding first 5 minutes). I IV STEADY STATE What is the acceptable coefficient of variation (CV) in oxygen consumption (vo2) and carbon dioxide (VCO2) production to reflect Steady State (SS) measure conditions and predict RMR? 10 minute protocol with 10% CV in vo2 and VCO2/minute using SS conditions (discarding first 5 minutes). 5 minute measures at <5% CV or 30 minutes with <10%CV provides results comparable to longer duration measures of EE, and the 5-min and 30-min measures are highly correlated. Sedation has a significant positive impact on successfully achieving the SS criteria. For spontaneously breathing, critically ill patients, the 5-min SS protocol produces reliable RMR. I GAS COLLECTION DEVICES What is the energy measurement difference when using different types of gas collection devices, such as facemask, mouthpieces with nose clips, or canopy? With no air leaks, comparable RMR measures can be achieved with facemask, mouthpieces with nose clips, or canopy. Conflicting data in one of five studies with mean RMR 7% higher in facemask and 9% higher for mouthpiece. I ROOM ENVIRONMENT What environmental characteristics controlled in research settings are necessary to apply in routine environmental settings to ensure an accurate RMR measure by IC? Posture: In settings to obtain RMR measures in healthy or ill adult patients, a good recommendation is to ensure that the individual is physically comfortable with the measurement position during the test and repeated measures are in the same position. Posture (sitting vs. reclined): One study of plus research design quality, with a wide weight range, indicates a sitting RMR measure is 100 kcals higher/day than a supine RMR. V V Humidity: The question of whether increased humidity changes RMR measurements, and its results are inconclusive. V Noise and lighting: Two narrative reviews representing expert opinion suggest that light and noise should be quiet for patients in critical care setting sand logically extend to other settings. IV No primary studies available in healthy adults (Grade V). Room Temperature: RMR is affected, to variable degrees in given individuals, by moderate cold exposure or ambient room temperatures outside of a comfortable zone (22-25 C) for healthy adults. V

16 Setting change (sleeping overnight as an inpatient vs. driving to an outpatient setting prior to measure): Low levels of physical activity related to daily living have minimal impact on RMR, provided that a suitable rest period follows the activity prior to measurement. I RESPIRATORY QUOTIENT Overall Conclusion Statement Should RQ be used to detect measurement error in adults? Respiratory quotient (RQ) is the ratio of vc02 and vo2 and under proper conditions is a function of the mix of substrates being utilized for metabolism. An RQ of <0.7 or > 1.0, can be used to identify unusual metabolic or respiratory conditions, failure to adhere to the fasting requirement of the protocol, and/or operator or equipment error. A repeated measurement under more optimal conditions should be considered if and RQ value is outside the range of 0.70 to 1.0. REST PERIOD LENGTHS What are the energy measurement differences if rest period lengths vary before measuring energy expenditure (EE) in healthy adults? A minimum rest period length of minutes is an adequate testing condition. Two narrative reviews are most frequently cited for the currently accepted 30-min. rest period. An international study of negative research quality design indicates individual RMR differences (< 70 kcal/day) between measurements performed after awakening, being transported in a wheelchair and a 7-min. rest period compared to a RMR measure taken after light physical activity and a 20 min. rest. I V* IV *12 Older adult COPD patients <24 HOUR DIURNAL What are the energy measurement differences between measurements performed on the same individual over various time periods assuming resting conditions and control for diet-induced thermogenesis, physical activity and body composition are followed? In healthy adults, repeated measures of RMR during 24 hours under fasting conditions or patients with continuous enteral or parenteral feedings vary on average around 5%. > 24 HOUR DIURNAL Measures of RMR in weight-stable, nonobese and obese individuals repeated after >24 hours will be within 10% of each other, with an individual variation of kcal/day.

17 Back to top Table 4.3: Considerations After Measurement Evidence Analysis Question HORMONE VARIABILITY: Do circulatory hormones that target cellular metabolism have a significant effect on RMR during or after hormone level changes resulting from aging, birth control medications, or selected medical treatments [i.e., hormone replacement therapy (HRT)]? HORMONE VARIABILITY: Thyroid Conclusion Statement Aging: In men after age 41 years, group mean rate of decline is kcal/day per year, while women s rate of decline is kcal/day each year after age 51 years. These declines are not fully explained by losses of fat-free mass (FFM). Thyroid-stimulating hormone, thyroxine, and triiodothyronine: Thyroid hormones are correlated with RMR in non-obese and obese men and women but only explain 1-9% of RMR variation; the correlations disappear after controlling for FFM. Healthy Adults Adult Patients Institutionalized (transitional care, sub-acute) Evidence Grade Acute/ Trauma Critically ill/ventilated Ethnic Populations Comments HORMONE VARIABILITY: Estrogen, Estradiol, and Progesterone In individuals who have lost weight (i.e., post-obese) or are known to have subclinical levels of thyroid hormones, there were no statically significant correlations when RMR is adjusted for lean body mass. Group mean RMR is increased 48 kcal/day in the luteal (post-ovulation) vs. follicular phase of the menstrual cycle and individual variability over the entire cycle ranges 2-10%. Oral contraception may increase group mean RMR up to 72 kcals/day but hormone replacement therapy does not impact RMR. Treatment of PCOS with ethinyl estradiol-cyproterone acetate may increase RMR in obese subjects, but should not be employed for energy balance management due to the associated deterioration of glucose control. I I V PHYSICAL ACTIVITY FACTORS* What physical activity factors should be used with measured resting metabolic rates? Non-obese: With a mean age of 62.3 ± 16.0 years (21-90 y age range), the physical activity levels ranged from 1.01 to 2.32 [mean 1.61±0.31] with a range of activity from sedentary to very active. Special Populations (Obese): In 44 obese adults (13 M; 31 F) with a mean age of 63.7 (6.2) years, the physical activity levels ranged from [mean (SD) 1.55 ± 0.28] with a range of activity from sedentary to very active. I I

18 Special Populations (Old and Very Old): In 21 older adults (12 M; 10 F), with a mean age of 79.2 ±4.2 years and years age range, the physical activity levels ranged from [mean /- 0.27] with only 2 individuals representing very active physical activity levels. I *Note. The physical activity factors were not part of the indirect calorimetry evidence analysis and therefore did not undergo the same rigorous review process; however, these could be considered after the IC is complete as part of a patient/client s nutrition care. Back to top

19 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > Tables > Table 5. Medication effects on RMR Table 5. Medication Effects on Resting Metabolic Rate The evidence analysis examining factors suspected to influence RMR included a review of medications. They were classified into five categories: central nervous system, autonomic, cardiovascular, endocrine and metabolic and anti-neoplastic agents (9). It is important to note that other medications within the same drug classes as those listed below may have the same impact on RMR; however, these were either not reported in the literature or did not meet the sorting criteria for inclusion in the analysis. Further, in some cases individual medications had an impact on RMR and, in other cases, combinations of medications impacted RMR. It is recommended that a physician or pharmacist be consulted for other or similar medications and their impact on RMR. Central Nervous System Decreased RMR Increased RMR No RMR impact Fluoxetine None noted Alfentanil Ibuprofen Midazolam Midazolam + Buprenorphine Midazolam + Fentanyl Midazolam +Fentanyl + Atracurium or Vecuronium Midazolam + Morphine Pentobarbital Thiopental Autonomic Carbamazepine Sibutramine Decreased RMR Increased RMR No RMR impact Midazolam + Morphine None noted None noted Pancuronium Vecuronium Cardiovascular Decreased RMR Increased RMR No RMR impact Propranolol None noted None noted Atenolol Endocrine and Metabolic Levothyroxine Glipizide rhgh Change in RMR inversely related to thyroid stimulating hormone (TSH) concentration Decreased RMR when compared with Metformin Increased RMR in persons with growth hormone deficiency Anti-neoplastic Decreased RMR Increased RMR No RMR impact Doxorubicin + Cyclophosphamide + Vindesine +Bleomycin + Prednisone + Methotrexate Doxorubicin + Cyclophosphamide + Fluorouracil + Methotrexate Zorubicin + Vincristine None noted None noted

20 Nutrition Care Process > Nutrition Assessment > Energy Expenditure > Determining Resting Metabolic Rate (Appendix) > References Selected References Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations to measured resting metabolic rate in healthy nonobese and obese individuals, a systematic review. In press. Lacey K, Pritchett E. Nutrition care process and model: ADA adopts road map to quality care and outcomes management. J Am Diet Assoc. 2003;103: Matarese LE. Indirect calorimetry: Technical aspects. J Am Diet Assoc. 1997;97:pS154-pS160. Mifflin MD, St. Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51: Harris JA Benedict FG. A biometric study of basal metabolism in man. Publication no. 279, Washington DC, 1919, Carnegie Institute. Owen, OE, Holup, JL, Dalessio, DA, Craig ES, Polansky M, Smalley JK, Kavle EC, Bushman MC, Owen LR, Mozzoli MA, Kendrick Z, Boden GH. A reappraisal of the caloric requirements of men. Am J Clin Nutr, 1987; 46: Owen OK Karle E Owen RS Polansky M Caprio S Mzzoli MA Kendrick ZV Bushman MC Boden G. A reappraisal of the caloric requirements of healthy women. Am J Clin Nutr. 1986; 44:1-19. WHO. Energy and protein requirements. Report of a joint FAO/WHO/UNU Expert Consultation. (Technical Report Series 724). Geneva: World Health organization, Dickerson RN, Roth-Yousey L. Medication effects on metabolic rate: A systematic review. Unpublished data. For a complete list of references see the Evidence Analysis Library at link from the ADA Research page on Members Only website:

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