32nd Annual International Conference of the IEEE EMBS Buenos Aires, Argentina, August 31 - September 4, 2010
Active Metabolic Weight Estimation Using Bioimpedance, Indirect Calorimetry and the Clino-Ortho Maneuver Miguel Cadena, Joaquín Azpiroz, Gisella Borja, Humberto Medel, Héctor Sandoval, Fausto Rodriguez, Francisco Flores and Pedro Flores +
Abstract— The resting energy expenditure (REE) and substrate utilization are computed by indirect calorimetry technique (ICT). The REE represents 80-85% of the total energy expenditure (TEE) but only accounts for the 7% of the actual body weight (ABW). The TEE is produced by the organs plus muscles, whereas the REE accounts only for the main organs. An important problem comes up when the REE is computed throughout the fat free mass (FFM) computation or anthropometric measurements because they do not explain the tremendous catabolic variability by ICT when subjects show the same body composition. Therefore, the aim of this work is to develop a method to compute the metabolic active weight (MAW) as a new form that may help to understand the catabolic activity of the body composition. The premise was the clino-ortho maneuver can split the ABW in two parts: one in which the MAW reflects the FFM catabolism while the second part was not considered since there is not energy requirement in it. The experiment design studied 37 young volunteers undergoing the clino-ortho maneuver during fast and postprandial conditions. The results showed REE increments of 21% during phase I (fast), while in phase II (postprandial) only 14% was achieved in ortho-postprandial. Therefore, the computed MAWs were 65.5Kg and 58Kg, respectively, when the ABW average was 70 Kg and the FFM was 50 Kg. One first conclusion was that the 15.5 Kg of the MAW above the FFM could explain a catabolic equivalence which can be exclusively related to the fast-ortho position which can help to classify exclusively the dynamic over activity of the FFM.
I. INTRODUCTION
M
etabolic active weight (MAW) is a new functional parameter to estimate the body composition in humans through out changes in the energy expenditure (EE). The estimation of body composition is important to determine the effects of physiological and pathological process on body morphology and structure of tissues and organs [1]. The standard utilization of the EE is through out the estimation of total energy expenditure (TEE) in order to estimate the energy balance in the field of clinical dietary. Then, TEE is computed using the resting energy expenditure Manuscript received on April 23, 2010. This work was supported by Universidad Autónoma Metropolitana- Iztapalapa. M. Cadena, J. Azpiroz , G. Borja H. Medel, H. Sandoval, F. Rodríguez, and F. Flores are with Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Ingeniería Eléctrica, México D.F. 09340, Phone: +52-558502-4569, (e-mail:
[email protected]). P. Flores are with Instituto Nacional de Cardiología Ignacio Chávez. Juan Badiando No.1 Tlalpan, Mexico DF (e-mail:
[email protected]).
978-1-4244-4124-2/10/$25.00 ©2010 IEEE
(REE) measurement, which it is considered as the 80-85 % of it, depending of the subject’s physical activity level. Then, the REE represents the energy requirement by the main 5 body organs (hart, lung, liver, kidney and brain) plus the energy used for termogenesis purpose. It is important to observe that 70 % of the REE is consumed by the main organs, which represent only 7 % of the actual body weight (ABW). The contrast is found in fat, muscle and other body parts, which represent 21, 32, and 40 % of the ABW, respectively [2]. On the other hand, the ABW can be modeled by two simple compartments. One section can be directly related to the MAW and the other can be considered as the fat mass (FM) compartment, which in theory does not require energy expenditure because it is considered as not metabolic active tissue. Therefore, one main goal is to compute the MAW using indirect calorimetry to quantify the body composition. This can be considered important when dietary plans are devote to patients with extreme body mass index (1830 Kg/m2) as a consequence of obesity, malnourish or caquexia [3-4]. The indirect calorimetry technique (ICT) is carried out performing a single 15 to 20 minute measurement test period of the oxygen consumption (VO2) and dioxide production (VCO2), where patient conditions are managed in order to assume steady state and thus the energy-mass balance equations are used to compute the metabolic substrate utilization and the REE. Then, VO2 and VCO2 are computed as if they were random variables with stationary averages and variances, so the REE measurement is extrapolated to 24 hours to provide predicted values for daily resting energy losses and TEE. Thus, the principal use of the ICT has been to generate nutritional strategies to control excess weight or to manage rapid metabolism changes due to under or over feeding intakes in critical patients close to risky situations. The ICT is considered to be the golden standard that non-invasively measures the metabolism, easy to use with ample clinical applications [5]. However, REE presents important measurement problems like the VO2 and VCO2 variability due to minimal steady state changes in the patients. In addition, it has been studied in one same population, with apparently the same body composition, the reasons why is obtained different REE measurement. These reasons can be age, gender, genetics, stress factors, dietary customs, etc. Thus, a major problem is
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how to develop a technique using the REE or in general the EE to differentiate only the fat free mass (FFM). One possible strategy is to use indirect calorimetry in conjunction with a physiological maneuver in which the EE acceleration measurement is directly related to the FFM [5-9]. To proof this hypothesis, this work presents a simple experiment where the active clino-ortho maneuver was applied to a volunteer subjects population. The ICT was implemented to measure the EE changes during two phases. First, during fast period the clino-ortho positions was applied, then during a second phase a controlled intake was provided to apply again the clino-ortho maneuver. Finally the MAW was computed as a fraction of the ABW using a derivative index as a function of the EE changes. The FFM was estimated by bioimpedance in order to obtain a correlation analysis. II. METHODOLGY
Phase II (subjects in postprandial): this phase started with a controlled intake of 500 Kcal after the phase I was finished. Then, 30 minutes after subjects were placed again in supine position with the half mask connected. Subjects were asked to stay in calm for another 5 minutes before gas collections started. In this phase II the ICT last about 15 minutes too. Then the subjects went to the ortho position holding 3 Kg hand weights so that the ICT last 15 minutes again. C. Rejection criteria • •
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A. The Model The MAW was considered divided in two parts inside the ABW. The first part was considered as a manner of a static section derived directly from the FFM %. The second part was considered in a dynamic way and computed from the difference between the EE expenditure at ortho position and the REE in clino position. Both parts were merged as in equation (1). EE − REE FFM % + REE % MAW ( Kg ) = ABW ( Kg ) 100
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Subjects out of control because of flu, fever, academia stress, or women in menstrual period. Consumption of any type of medical prescription, alcohol, coffee or tea during the last 12 hours before the experiment commences. To show up glucose measurement above 115 mg/dL or symptom of intolerance to the clino-ortho maneuver like dizziness or temporary faint. Intolerance to support 3 Kg hand weights during the ortho maneuver during phase I and phase II. Variation coefficient (VC) for the VO2 and VCO2 greather than 10% during REE measurement in phase I as a criteria of the subject’s physiological steady state
D. Intrumentation
(1)
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B. Experiment Design
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Studies using the ICT, bioimpedance and anthropological measurement were achieved in a student volunteer population of 37 subjects (15 women and 22 men) with ages between 20 and 40 years. The subjects were selected with BMI grater than 18 and less than 40 (Kg/m2), without chronic diseases or metabolic disorders, and with sedentary life style. The experimental conditions were subjects in fast condition (Phase I), then subjects were given a controlled intake of 500 Kcal (juice and ensure can) to produce a 30 minutes postprandial condition (Phase II). The experiment was performed during the early morning hours at 2400 meters above de the sea level (Mexico City) with ambient temperature between 20 and 23 ºC. Phase I (subjects in fast): the experiment started with glucose measurement, then subjects were placed in supine position with half mask connected, to collect expired gases, to the calorimeter using 22 mm tubing. Subjects were asked to stay in calm for 5 minutes before gas collections started. In this phase I the ICT last about 15 minutes to assure steady state measurements. Then the subjects went to the ortho position holding 3 Kg hand weights in each hand. Again, the ICT last 15 minutes starting after 3 minutes when subjects were placed in the ortho position.
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Research Indirect Calorimeter (Utah Medical Products Inc, model MGM-2) with mixing chamber. Commercial Bioimpidance equipment (Inbody 720, Biospace Inc) with weight scale included. Commercial glucometer and height (Medisense Inc).
E. Data Analysis Data groups were conformed from the 37 subject’s measurements in order to perform statistical analysis. The groups were divided by the VC in paired and non-paired groups as follow: Group 1: VC
