Resting Metabolic Rate (RMR) is computed using VO2and VCO2short time 15-minute window measurement with Indirect Calorimetry (IC) instruments designed with mixing chamber. Steady state condition using a 10% variation coefficient criteria is the main objective to achieve metabolic long time prediction reliability. This study address how susceptible is the steady state VO2, VCO2measurement condition to the clino-orthostatic physiological maneuver. 30 young healthy subjects were analyzed. Only 18 passed the 10% variation coefficient inclusive criteria. They were exposed to 10 minutes clino-stage and 10 minutes orthostage. The hypothesis tests show not statistical significance (p< 0.1) in the average and variance analysis. It is concluded that the steady state is not influenced by the patient position IC test, probably because IC mixing chamber instruments are insensitive to detect a mayor physiological dynamics changes that can modify the steady state definition.

Abstruct-Several evaluation methods exist to search the link between the Metabolic System (MS) and the Autonomic Nervous System (ANS). Most of them are invasive and they are unable to follow fast adaptable mechanism of the MS and ANS response. In this work we explore a different non-invasive method using Indirect Calorimetry (IC) and Heart Rate Variability (HRV). We used the clino-orthostatism maneuver as ANS oriented stimulus on 7 subjects to see the metabolic response and the set up sensitivity to the experiment. The results agree with the physiology knowledge and with our hypothesis on the stimulus-response paradigm. However, the population, the instrumentation and some physiological hypothesis used in this experiement are still under questioning.

This paper proposes a discrete random time series modeling for the VO2 and VCO2 measurement in the indirect calorimetry technique (ICT). Mathematical equations are developed in order to establish clear differences between the breath-by-breath and mixing chamber measurement based calorimeters. This simple model offers not only a physiological ICT definition approach but also defines the idea of VO2 and VCO2 short-term variability information for research. The preliminary results show a new physiological information when a computer oriented algorithm model implementation was applied to a data acquisition system in order to obtain the power spectrum analysis from a typical observation subject submitted to the clino-ortho maneuver.

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HD and HDF as hemodialytic therapies normally alter patient's haemodynamic stability, due to the inflammatory response to extracorporeal blood circuit, producing increment of the core temperature (+1.0 degrees C). However, such increase in temperature could be controlled by lowering dialysate's temperature using two main modalities techniques (isothermic and thermoneural) with different patient's thermal balance consequences, not yet well studied. In this work, energy expenditure (EE) was measured by indirect calorimetry in a group of 12 patients waiting kidney transplant. In each patient, EE was assessed (as a power generation) during isothermic and thermoneutral modalities as a manner of cross and prospective study (a) at before therapy, (b) during therapy and (c) at the end of the HDF therapy. Wheraeas, power extraction was measured by a BTM (Blood Temperature Monitor from Fresenius Inc) in order to determine power balance in a thermodynamic model of the extracorporeal circuit. The results showed significant differences in the power balance when EE at during therapy was subtracted from the EE at before therapy. Then, EE increments were 32 Kcal/4-hours during isothermic and 3.6 Kcal/4-hours during thermoneutral HDF sessions (p<0.05). While, BTM totals power extraction was 91 and 16.1 Kcal/4-hours (p<0.05), respectively. Additionally, it was estimated a 12% of EE/day increment during HDF-isothermic at during therapy stage compared with none significative EE increment during thermoneutral modality. The statistical evidence confirmed the expected hypothesis that both modalities affect in different manner the patient's EE. Also, we conclude there is no satisfactory data interpretation when the thermodynamic model was applied expecting null balance between EE increment and BTM power extraction. Therefore, these findings force to think there is need of different BTM design and measurement setting with ability to follow dynamic patient's EE changes with the purpose to achieve a better power balance.