Handheld Indirect Calorimeter Research Articles

Indirect Calorimetry Performance Using a Handheld Device Compared to the Metabolic Cart in Outpatients with Cirrhosis.

Addressing malnutrition is important to improve health outcomes in outpatients with cirrhosis, yet assessing energy requirements in this population is challenging. Predictive equations of resting energy expenditure (REE) are thought to be unreliable, and traditional indirect calorimetry is expensive and infrequently available for clinical use. The accuracy of REE predictions using a MedGem® handheld indirect calorimeter, the Harris Benedict Equation (HBE), the Mifflin St. Jeor equation (MSJ), and the gold standard Vmax Encore® (Vmax) metabolic cart was compared. The REE of cirrhotic pre-liver transplant outpatients was analyzed using each of the four methods. Agreement between methods was calculated using Bland–Altman analysis. Fourteen patients with cirrhosis participated, and were primarily male (71%) and malnourished (subjective global assessment (SGA) B or C 64%). Lin’s concordance coefficient (ρC) for MedGem® vs. Vmax demonstrated poor levels of precision and accuracy (ρC = 0.80, 95% confidence interval 0.55–0.92) between measures, as did the HBE compared to Vmax (ρC = 0.56, 95% confidence interval 0.19–0.79). Mean REE by MedGem® was similar to that measured by Vmax (−1.5%); however, only 21% of REE measures by MedGem® were within ±5% of Vmax measures. Wide variability limits the use of MedGem® at an individual level; a more accurate and feasible method for determination of REE in patients with cirrhosis and malnutrition is needed.

Handheld Indirect Calorimetry as a Clinical Tool for Measuring Resting Energy Expenditure in Children with and without Obesity.

Background: Resting energy expenditure (REE) is a valuable measure in clinical management of obesity and other chronic illnesses. Gold standard methods for measuring REE (e.g., Douglas bags and metabolic cart) are too expensive and cumbersome for an outpatient clinical setting. The purpose of this study was to determine the accuracy of a handheld indirect calorimeter (HHIC) and prediction equations (PEs) for measurement of REE in youth with and without obesity. Methods: Fifty-three children and adolescents (12.8 ± 4.3 years, 50.9% female) had REE measured first with a MedGem™ HHIC for 10 minutes, followed by a reference indirect calorimeter system (ParvoMedics TrueOne 2400™) with hood canopy and dilution pump for 30 minutes. REE was also estimated using nine PEs as follows: Henry-1, Henry-2, Schofield, World Health Organization, Molnar, Muller, Herrmann, Schmelzle, and Harris-Benedict. Concordance correlation coefficients and Bland-Altman analyses were used for comparisons among PEs, MedGem HHIC, and metabolic cart. Results: The observed correlation between the HHIC and the reference system was rc = 0.89 with a mean bias of 2.27 ± 3.41 kcal/(kg·d) (9.1% ± 14.7%). Regarding PE, Molnar had the highest agreement with the reference system [rc = 0.93, bias of 2.17 ± 2.04 kcal/(kg·d); 9.8% ± 8.1%], followed by Harris-Benedict (rc = 0.89; 13.8% ± 8.9%), Henry-2 (rc = 0.89; 15% ± 7.6%), and Henry-1 (rc = 0.86; 16.7% ± 7.3%). All PEs were less accurate for children with overweight/obesity. Conclusions: Compared to PE, the HHIC provided more accurate REE estimates for children across the age and BMI spectrum, although positive bias was present throughout. Difference in positive bias between the HHIC and the Molnar equation may be clinically significant for youth with overweight/obesity.

PTU-094 The Assessment of Resting Energy Expenditure in Patients with Cirrhosis Remains Problematic

Introduction Patients with cirrhosis are frequently malnourished and this has a detrimental effect on outcome. Accurate assessment of resting energy expenditure (REE) would facilitate management by providing an objective measure on which to base individualised recommendations for nutritional support. REE can be accurately measured using indirect calorimetry but this technique cannot be used easily in the clinical setting. A number of portable bedside techniques for estimating REE have now been developed although they have not, to date, been validated in this patient population. The aim of the present study was to validate the use of alternative methods for assessing REE against the ‘gold standard’ of indirect calorimetry. Methods The study population comprised 19 patients (12 men: seven women; mean [range] age, 60.3 [31–83] yr) with cirrhosis; 11 (57.9%) were adequately nourished, three (15.8%) moderately malnourished and five (26.3%) severely malnourished. REE was measured, under standardised conditions, using a precision, indirect calorimeter (Cortex Metamax 3 B). Additional REE measurements were undertaken, at the same sitting, using: (i) the Medgem Handheld indirect calorimeter; (ii) the Sensewear Pro 3 armband direct calorimeter; and, (iii) the Bodystat Quadscan 4000 bioelectric impedance analyzer. REE was also predicted using the generic Harris-Benedict, Schofield, Mifflin, and Cunningham equations and the disease-specific Muller and Morgan & Madden equations. 1 Results The mean (±1 SD) REE measured using the Metamax indirect calorimeter was 1368±456.4 Kcal/24 hr. REE measurments provided by the alternative methods ranged from 1188.1 kcal/24 hr less to 722.6 Kcal/24 hr more than the Metamax values. The Medgem provided the ‘least inaccurate’ REE measurements but values still differed by approximately ±700 Kcal/24 hr. The differences in measurement values between the portable devices and the ‘gold standard’ were inconsistent and bidirectional. Likewise, REE values obtained using the prediction equations ranged from 1018.6 kcal/24 hr less to 1468.3 Kcal/24vhr more than the Metamax values. The generic Mifflin equation provided the ‘least inaccurate’ REE estimates but values still ranged from 887.7 Kcal less to 558.4 Kcal/24 hr more than the Metamax values. Conclusion Measurements of REE provided using these bedside techniques and estimated using the predication equations were not sufficiently accurate to be of value, in the clinical setting, either for the assessment of nutritional requirements nor for monitoring over time to assess disease progression or responses to nutritional therapy. Reference 1 Madden AM, Morgan MY. Resting energy expenditure should be measured in patients with cirrhosis, not predicted. Hepatology 1999; 30 :655–664. Disclosure of Interest None Declared

Does H. pylori Colonization Impact Basal Metabolic Rate?

Introduction: Ghrelin is produced mainly by the stomach and may influence energy expenditure. H. pylori colonization is associated with reduced circulating ghrelin levels. We hypothesized that H. pylori colonization impacts resting metabolic rate (RMR). The aims of this study were to: 1.) evaluate the reproducibility of RMR measurements via a hand-held indirect calorimeter in healthy young adults, 2.) compare the RMR between individuals with and without H. pylori colonization, and 3.) analyze the change in RMR after H. pylori eradication. Methods: For the validation aim of the study, 7 healthy volunteers were enrolled and evaluated for demographic as well as clinical information. The MedGem indirect calorimeter device was used for all measurements. Weekly-standardized RMR and oxygen consumption (VO2) measurements were obtained for 4 consecutive weeks. For the second and third aims, 44 participants were evaluated at baseline for H. pylori status. All H. pylori-positive participants were treated with standard eradication regimens. RMR data was collected at baseline and subsequent follow-up visits (6 weeks, 3 months, and 6 months). Results: For the validation aim of the study, the pairwise correlations for weekly RMR measurements were all higher than 0.70, and the intra-class correlation coefficient (ICC) of the multiple measurements of RMR was 0.987 over 4 weeks. For the second and third aims, 17% of all participants were male, and the mean age was 24.57 years. The mean baseline BMI for all participants was 24.03. The mean baseline RMR for the H. pylori-negative and positive participants was 1297.8 and 1421.4, respectively. There was no significant difference in baseline RMR by H. pylori status (p=0.631). The absolute mean change in RMR from baseline to 6 weeks post treatment was greater for the H. pylori-positive group than the negative group (18.6 vs. -2.5), although not statistically significant. Similarly, the mean change in RMR from baseline to 3 months post treatment was greater for the H. pylori-positive group than the negative group (75.0 vs. 62.5). For the H. pylori-positive group, there was a significant difference between the mean RMR at baseline compared to the 3-month follow-up (p=0.034). Conclusion: Measurement of resting metabolic rate via a hand-held indirect calorimeter in young healthy adults is reproducible. H. pylori-colonization, as well as eradication, impacts RMR. Further assessment of the long-term metabolic consequences of H. pylori eradication should be undertaken.

Assessing Energy Expenditure in Obese Adolescents in a Clinical Setting: Is the Handheld Indirect Calorimeter Valid and Accurate?

Assessing Energy Expenditure in Obese Adolescents in a Clinical Setting: Is the Handheld Indirect Calorimeter Valid and Accurate?

An Evaluation of a Handheld Indirect Calorimeter Against a Standard Calorimeter in Obese and Nonobese Adults

Handheld indirect calorimetry has the potential to allow simple and inexpensive measurement of resting metabolic rate in spontaneously breathing people. However, validation work on these devices is contradictory. The purpose of the current study was to determine the bias and level of agreement of oxygen consumption and resting metabolic rate as measured by a handheld indirect calorimeter against a standard open-circuit indirect calorimetry cart. One hundred community-living, spontaneously breathing, ambulatory nonobese and obese adults were studied in single sessions by a single investigator. Sequential measurements were undertaken using the handheld indirect calorimeter and the standard metabolic cart. Measurement sequence was varied randomly. The mean value for oxygen consumption and metabolic rate of the 2 devices was not significantly different. However, agreement between the 2 devices was only 43% in nonobese and obese participants, and there was proportional and fixed bias, with the handheld calorimeter tending to produce a higher value for oxygen consumption and resting metabolic rate. Limits of agreement for resting metabolic rate between the 2 calorimeters were -240 to +300 kcal/d. Measurements of resting metabolic rate by the handheld indirect calorimeter tested in this study are not equivalent to measurements by standard indirect calorimetry.

Comparison of Various Preparations of Gynostemma pentaphyllum (Jiaogulan) and its Main Active Constituents, Gypenoside Saponins, on Resting Metabolic Rate: Controlled Human Clinical Study

We have compared efficacies of 3 different Gynostemma pentapyllum (jiaogulan) samples on resting metabolic rate (RMR) by hand‐held indirect calorimeter in healthy human adults (n=10). The samples were jiaogulan leaf extract (A), jiaogulan blend composed of extracted and freeze‐dried whole Gynostemma plant (B), and JULE of the OrientTM (JULE), an herbal blend consisting of B plus goji, astragalus, codonopsis, jujube, longan, luohanguo, rhodiola, schisandra, açai, amalaki, aronia, camu‐camu, elderberry, ginger, Japanese sophora, blueberry, bilberry, lychee, cranberry, cherry and reishi mushroom. Total saponins were adjusted at the same level in all samples. Each sample (60 ml) was separately consumed immediately before a nutritional beverage (360 kcal) after 12 h fast. B increased RMR by 178 kcal over baseline level (1,703 kcal) at 2 h post‐intake. JULE intake further increased RMR by 231 kcal significantly (P<0.05), about 14% of baseline level. A increased RMR by 134 kcal over baseline, which was same level with control (139 kcal), and was significantly lower than the effect of B or JULE. These results suggest that constituents other than saponins in jiaogulan may have stimulating effects on metabolism, that whole plant jiaogulan may have greater efficacies than leaf alone, and that the synergistic effect of various herbs in the JULE causes significant increase in the effect of jiaogulan on human metabolism.

Hand-Held Indirect Calorimeter Offers Advantages Compared with Prediction Equations, in a Group of Overweight Women, to Determine Resting Energy Expenditures and Estimated Total Energy Expenditures during Research Screening

ObjectiveTo compare standardized prediction equations to a hand-held indirect calorimeter in estimating resting energy and total energy requirements in overweight women. DesignResting energy expenditure (REE) was measured by hand-held indirect calorimeter and calculated by prediction equations Harris-Benedict, Mifflin-St Jeor, World Health Organization/Food and Agriculture Organization/United Nations University (WHO), and Dietary Reference Intakes (DRI). Physical activity level, assessed by questionnaire, was used to estimate total energy expenditure (TEE). SubjectsSubjects (n=39) were female nonsmokers older than 25 years of age with body mass index more than 25. Statistical analysesRepeated measures analysis of variance, Bland-Altman plot, and fitted regression line of difference. A difference within ±10% of two methods indicated agreement. ResultsSignificant proportional bias was present between hand-held indirect calorimeter and prediction equations for REE and TEE (P<0.01); prediction equations overestimated at lower values and underestimated at higher values. Mean differences (±standard error) for REE and TEE between hand-held indirect calorimeter and Harris-Benedict were −5.98±46.7 kcal/day (P=0.90) and 21.40±75.7 kcal/day (P=0.78); between hand-held indirect calorimeter and Mifflin-St Jeor were 69.93±46.7 kcal/day (P=0.14) and 116.44±75.9 kcal/day (P=0.13); between hand-held indirect calorimeter and WHO were −22.03±48.4 kcal/day (P=0.65) and −15.8±77.9 kcal/day (P=0.84); and between hand-held indirect calorimeter and DRI were 39.65±47.4 kcal/day (P=0.41) and 56.36±85.5 kcal/day (P=0.51). Less than 50% of predictive equation values were within ±10% of hand-held indirect calorimeter values, indicating poor agreement. ConclusionsA significant discrepancy between predicted and measured energy expenditure was observed. Further evaluation of hand-held indirect calorimeter research screening is needed.

Effect of Standardized Lycium barbarum (Goji) Juice, GoChi® Intake on Resting Metabolic Rate and Waist Circumference: Randomized, Placebo‐controlled, Double‐blind Clinical Studies

We examined the effects of consuming Lycium barbarum fruit juice (GoChi®, 120 ml/day) on morphometric parameters and resting metabolic rate (RMR) in healthy human adults in 2 separate randomized, double‐blind, placebo‐controlled clinical studies. GoChi juice is standardized for its main active constituents, Lycium barbarum polysaccharides, based on the amount of fresh berries traditionally used.Study‐1Under free‐living conditions, subjects (average age=33.6, body mass index (BMI) =29.3kg/m2) took either GoChi or placebo samples in a 30‐day intervention trial. Waist circumference in the placebo group (N=19) increased significantly by 2.2 cm on Day 30 at post‐intervention compared to pre‐intervention. GoChi group (N=20) maintained pre‐intervention measurements. Changes in waist circumference per caloric intake in GoChi group tended to be lower than placebo group. Body weight and other parameters were not significantly different between groups or pre‐ and post‐intervention.Study‐2The effect of a single bout of consuming either GoChi or placebo control samples on RMR was investigated by hand‐held indirect calorimeter (average age=34.5, BMI=28.2 kg/m2). GoChi intake (120 ml) (n=6) significantly increased RMR 53% more than placebo (n=10) at 2 hours after consumption.These results suggest that GoChi may have metabolic effects which are reflected in waist circumference.

Comparison of Resting Energy Expenditure Prediction Methods With Measured Resting Energy Expenditure in Obese, Hospitalized Adults

Several methods are available to estimate caloric needs in hospitalized, obese patients who require specialized nutrition support; however, it is unclear which of these strategies most accurately approximates the caloric needs of this patient population. The purpose of this study was to determine which strategy most accurately predicts resting energy expenditure in this subset of patients. Patients assessed at high nutrition risk who required specialized nutrition support and met inclusion and exclusion criteria were enrolled in this observational study. Adult patients were included if they were admitted to a medical or surgical service with a body mass index > or = 30 kg/m(2). Criteria excluding patient enrollment were pregnancy and intolerance or contraindication to indirect calorimetry procedures. Investigators calculated estimations of resting energy expenditure for each patient using variations on the following equations: Harris-Benedict, Mifflin-St. Jeor, Ireton-Jones, 21 kcal/kg body weight, and 25 kcal/kg body weight. For nonventilated patients, the MedGem handheld indirect calorimeter was used. For ventilated patients, the metabolic cart was used. The primary endpoint was to identify which estimation strategy calculated energy expenditures to within 10% of measured energy expenditures. The Harris-Benedict equation, using adjusted body weight with a stress factor, most frequently estimated resting energy expenditure to within 10% measured resting energy expenditure at 50% of patients. Measured energy expenditure with indirect calorimetry should be employed when developing nutrition support regimens in obese, hospitalized patients, as estimation strategies are inconsistent and lead to inaccurate predictions of energy expenditure in this patient population.

Measuring Energy Expenditure in Community-Dwelling Older Adults: Are Portable Methods Valid and Acceptable?

The objective of this study was to assess the validity and acceptability of a handheld indirect calorimeter for measurement of resting energy expenditure in a sample of community-dwelling older adults. It was a measurement study involving 48 healthy community-dwelling older adults. Assessment of resting energy expenditure was performed in 48 healthy older adults under fasting conditions using the Europa Gas Exchange Monitor (GEM; ventilated hood indirect calorimeter, NutrEn Technology Ltd, Cheshire, UK) and the MedGem (handheld indirect calorimeter, HealtheTech Inc, Golden, CO). An eight-item self-administered survey was used to determine the acceptability of the two measurement devices. Bias and limits of agreement were calculated to determine the level of agreement between the two measurements. The Wilcoxon signed-ranks test was used to test for significant differences across items of the self-administered survey. Participants mean age was 80 years and mean body mass index (calculated as kg/m 2) was 23. Mean (95% confidence interval) resting energy expenditure was 1,149 kcal/day (1,086, 1,194) and 1,489 kcal/day (1,386, 1,592) for the traditional and handheld indirect calorimeter, respectively; paired t test P<0.001. Mean bias and limits of agreement were 349 kcal (−270, 969) or 5 kcal/kg/day (−3.6, 13.2) with least products regression resulting in a slope of b 1=1.9 (95% confidence interval 1.2, 2.7, P<0.05). The handheld indirect calorimeter was less acceptable to participants than the ventilated hood indirect calorimeter. Measurement of resting energy expenditure from the handheld indirect calorimeter used in this study is not acceptable for use in healthy older adults given the magnitude of the overestimate, the wide limits of agreement, the significant slope of the bias, and the discomfort experienced by the participants.

Employing RMR Technology in a 90-Day Weight Control Program

Objective: The purpose of this study was to evaluate the efficacy of a weight management program using indirect calorimetry to set energy goals. Methods: 54 overweight, active duty adult employees of the US Air Force (age 18–46 years, BMI 25.2–35.6 kg/m²) participated in this quasi-experimental control design study. All participants were enrolled in a four-session US Air Force ‘Sensible Weigh’ group weight control program. Treatment participants received a personalized nutrition energy goal message developed using measured resting metabolic rate (RMR) from a hand-held indirect calorimeter (MedGem®). Usual care participants received a nutritional message using a standard care equation (25 kcal/day × body weight) to set energy intake goals. Results: Treatment participants lost significantly more weight than usual care participants (p ≤ 0.05). Difference in weight loss between the treatment and usual care group were –4.3 kg ± 3.3 vs. –1.8 kg ± 3.2, respectively. There were no significant differences in reported food intake or energy expenditure between groups. Conclusion: The use of indirect calorimetry to assess RMR and set energy intake goals positively influences weight loss success in overweight Air Force personnel.

A Systematic Review on Use of a Handheld Indirect Calorimeter to Assess Energy Needs in Adults and Children

With the number of individuals becoming overweight or obese, health care professionals are in need of accurate, reliable, and convenient tools to help personalize weight-loss programs. Recently, a new handheld indirect calorimeter (i.e., MedGem/BodyGem; also know as "Gem") was introduced as a convenient way to assess resting metabolic rate (RMR) to determine daily energy needs. Several validation and comparison studies were conducted to determine whether the Gem device is accurate and reliable, and results from these studies are mixed. Fourteen human studies (12 adult, 2 pediatric) were conducted, and 12 met the established criteria for this review. In all Douglas-bag (DB; n = 4) validation studies, the Gem device was not significantly different than the DB (mean difference adult +/-1%, pediatric +/-1%). The intraclass reliability of the Gem ranged from 0.97 to 0.98, and the interclass reliability to the DB ranged from 0.91 to 0.97. Although few (n = 2) studies have demonstrated that the Gem device measures RMR significantly lower (-8.2% to 15.1%) than traditional metabolic carts, it performs very comparably (RMR values 0.1-4.0%, interclass reliability 0.76-0.92) to traditional metabolic carts in most (n = 6) of the comparison studies. Based on these data, the Gem device is a valid and reliable indirect calorimeter for energy assessment in most adults and children.

A Comparison of Measured Resting Energy Expenditure (REE) with Predicted Resting Energy Expenditure (REE) in Morbidly Obese Patients

Text: Purpose: To compare, in patients with morbid obesity, resting energy expenditure (REE) measured by a handheld indirect calorimeter (MedGem) with predicted energy expenditure as calculated by 8 different prediction equations Methods: REE was measured by a handheld indirect calorimeter (MedGem) for 34 female morbidly obese patients. Eight different equations were used to calculate predicted REE. For each predicted REE, the difference from the MedGem REE was calculated for each patient. For each method, differences were plotted against the corresponding means of the MedGem and predicted measures. Plots were used to determine whether a systematic relationship existed between the differences and means. Bland-Altman limits of agreement were calculated for each predicted REE with / 500kcal/day established as a priori clinically unacceptable error. Disagreement between the MedGem (MG) REE and the predicted REEs was defined as greater than 10%. Results: The lowest amount of bias was observed for Mifflin-St Jeor (MSJ) equation using actual body weight, which was on average 129.52 higher than MedGem. Following the MSJ equation was the HarrisBenedict equation using actual body weight, which was on average 172.14 higher than MedGem. The mean bias (Predicted REE MG) was 10% for both equations with limits of agreement between 457.74 and 716.78 kcal/day (MSJ) and 391.03 and 735.31 kcal/day (HB). Since the mean bias was 10 % for both equations and limits of agreement exceeded / 500kcal/day, when compared to MG REE, both predictive equations may not be clinically acceptable for use with this population.

MedGem Hand‐Held Indirect Calorimeter Is Valid for Resting Energy Expenditure Measurement in Healthy Children

To assess the validity of a new hand-held indirect calorimeter [MedGem (MG)] in the determination of resting energy expenditure (REE; kilocalories per day) in children. One hundred male (n = 54) and female (n = 46) children (10.6 +/- 3.2 years, 43.9 +/- 19.0 kg, 146.1 +/- 18.8 cm, 19.6 +/- 4.9 kg/m(2)) participated. Children arrived at the University of Oklahoma body composition laboratory between 5:30 am and 6:15 am after an overnight fast. On arrival, subjects voided and remained quietly in the supine position for 15 minutes before testing. REE was measured by indirect calorimetry (in random order), with both the MG (sitting upright) and the criterion Delta Trac II (DT) (supine). Data are reported as the mean +/- standard deviation. The mean MG REE (1452 +/- 355 kcal/d) was significantly higher than DT REE (1349 +/- 296 kcal/d, p < 0.001). Bland-Altman analysis revealed a mean bias (MG - DT) of 104 kcal/d, with limits of agreement of -241 to +449 kcal/d. To examine the difference in subject positioning, an independent sample of 38 subjects performed the MG in its normal position (sitting) and holding the MG in a supine position. REE by the MG in the sitting position (1475 +/- 350 kcal/d) was significantly (p < 0.05) higher than the MG in the supine position (1419 +/- 286 kcal/d). The mean difference in REE between MG and DT was relatively small (103 kcal/d) but significant; however, a portion of this difference may have been related to differences in subject positioning. These preliminary data indicate that the MG shows promise as a valid tool in the assessment of REE in children.

Comparison of Two Systems of Measuring Energy Expenditure

Health care professionals typically use resting metabolic rate (RMR) via indirect calorimetry to determine a person's energy expenditure. Traditional indirect calorimetry measurements involve an expensive, cumbersome piece of equipment that requires careful calibration. The recent development of a handheld indirect calorimeter makes it easier to measure RMR. The purpose of this study was to compare simultaneous measurements of RMR with handheld and traditional indirect calorimeters. Healthy, free-living subjects (n = 50) age 18 years and older were tested simultaneously with both indirect calorimeters. All subjects breathed through the handheld device using a mouthpiece while wearing noseclips to prevent leaks. The handheld indirect calorimetry device was placed inside a canopy. The exhaled gas from the handheld was positioned directly over the inlet to the port delivering gases to the traditional device's mixing chamber. The canopy facilitated the simultaneous collection of all expired gases into the traditional device. During the measurement, oxygen consumption and RMR were continuously recorded on a personal computer. Mean oxygen consumption and RMR did not significantly differ between the two devices, with a mean difference of 0.58 +/- 15.33 mL/min (p = .790) and 4.66 +/- 113.39 kcal/day (p = .773) and an absolute difference of 12.3 +/- 8.99 mL/min and 86.58 +/- 72.32 kcal/day, respectively. Correlation coefficients for oxygen consumption and RMR were 0.945 and 0.941, respectively. No significant difference was found between the measurements of indirect calorimetry with the MedGem (HealtheTech, Golden, CO) device compared with the DeltaTrac device (Datex-Ohmeda, Madison, WI). These findings suggest that the handheld indirect calorimeter may provide an accurate measure of oxygen consumption and RMR measurements for spontaneously breathing subjects.

Effects of Home Parenteral Nutrition on Resting Metabolic Rate: A Case Study

Resting metabolic rate (RMR) measurement by indirect calorimetry is often used in acute care; however, indirect calorimetry is rarely performed on patients treated at home with complex therapies such as home parenteral nutrition (HPN). A new hand-held indirect calorimeter is now available to measure RMR and oxygen consumption (VO2). This is a case study of a 35-year-old female who had her RMR and VO2 measured at rest while receiving cyclic HPN and while off of HPN over a period of 8 days. Results indicate that her RMR was higher while receiving HPN. Measuring RMR in patients receiving HPN may be very beneficial to avoid underfeeding and overfeeding. It will be important for the clinician to note if the patient is receiving HPN at the time of the measurement because RMR may be affected by HPN infusion.

Validation of the BodyGem hand-held calorimeter.

To assess the validity and reliability of a hand-held indirect calorimeter. Resting metabolic rate (RMR) was measured on two separate mornings. A heterogeneous sample of 41 healthy adults. RMR using both a metabolic cart (Sensormedics 2900, SM-2900) and a hand-held indirect calorimeter (BodyGem, BG). There were no trial-to-trial differences in RMR measured by the BG (6756+/-163 vs 6697+/-163 kJ/day) or the SM-2900 (6400+/-163 vs 6396+/-167 kJ/day). RMR measured by the BG was significantly higher than that measured by the SM-2900 during both trials. In a sample of 10 subjects, the energy cost of holding the BG in position was determined to be (0.17+/-0.04 kJ/min, or 255+/-84 kJ/day). After applying this adjustment, the differences between systems were no longer significant during trial 1 (mean difference=101+/-67 kJ/day) or trial 2 (46+/-75 kJ/day). In overweight and obese individuals, RMR measured by the BodyGem was more accurate than that estimated by the Harris-Benedict equations. The BodyGem provides valid and reliable measurements of RMR. The BodyGem produces significantly higher values than the Sensor Medics 2900 indirect calorimeter, with the increase largely due to an increased energy demand required to hold the BG in position.