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1.  VO2 and VCO2 variabilities through indirect calorimetry instrumentation 
SpringerPlus  2013;2:688.
The aim of this paper is to understand how to measure the VO2 and VCO2 variabilities in indirect calorimetry (IC) since we believe they can explain the high variation in the resting energy expenditure (REE) estimation. We propose that variabilities should be separately measured from the VO2 and VCO2 averages to understand technological differences among metabolic monitors when they estimate the REE. To prove this hypothesis the mixing chamber (MC) and the breath-by-breath (BbB) techniques measured the VO2 and VCO2 averages and their variabilities. Variances and power spectrum energies in the 0–0.5 Hertz band were measured to establish technique differences in steady and non-steady state. A hybrid calorimeter with both IC techniques studied a population of 15 volunteers that underwent the clino-orthostatic maneuver in order to produce the two physiological stages. The results showed that inter-individual VO2 and VCO2 variabilities measured as variances were negligible using the MC while variabilities measured as spectral energies using the BbB underwent 71 and 56% (p < 0.05), increase respectively. Additionally, the energy analysis showed an unexpected cyclic rhythm at 0.025 Hertz only during the orthostatic stage, which is new physiological information, not reported previusly. The VO2 and VCO2 inter-individual averages increased to 63 and 39% by the MC (p < 0.05) and 32 and 40% using the BbB (p < 0.1), respectively, without noticeable statistical differences among techniques. The conclusions are: (a) metabolic monitors should simultaneously include the MC and the BbB techniques to correctly interpret the steady or non-steady state variabilities effect in the REE estimation, (b) the MC is the appropriate technique to compute averages since it behaves as a low-pass filter that minimizes variances, (c) the BbB is the ideal technique to measure the variabilities since it can work as a high-pass filter to generate discrete time series able to accomplish spectral analysis, and (d) the new physiological information in the VO2 and VCO2 variabilities can help to understand why metabolic monitors with dissimilar IC techniques give different results in the REE estimation.
PMCID: PMC3884081  PMID: 24422180
VO2 and VCO2 variabilities; Gas exchange variability; Variability; Open circuit hybrid calorimeter; VO2 and VCO2 power spectrum
2.  Imaging Facilities for Basic Medical Units: A Case in the State of Guerrero, Mexico 
Journal of Digital Imaging  2010;24(5):857-863.
This work presents the methodology to design a small imaging unit in a small regional hospital that takes into account the real imaging needs in the region regardless of current administrative guidelines. The situation of the imaging facilities in Mexico’s states is studied and compared with other countries, and a project plan is designed for the specific state (Guerrero) where the clinic is to be located. The proposal includes the acquisition of a basic suite of modalities that include an ultrasound system, a mammography unit, and a conventional X-ray system in addition to a CT system that is not available anywhere within the state. The system should be primarily digital and should incorporate a simple picture archiving and communications system that can be the basis of a future telemedicine unit. The conclusion of this study also proposes changes in the segmented and pyramidal structure of the Mexican health system in order to provide higher quality care at the lower level, to reduce bottlenecks, and to provide higher quality health care near the patient’s home.
PMCID: PMC3180540  PMID: 21042831
Medical imaging; Healthcare systems; Medical technology assessment; PACS; Diagnostic imaging; Digital imaging; Digital radiography; Medical economics; Health technology; Radiology department; Hospital

Results 1-2 (2)