Analysis of gaseous exchange in open-circuit indirect calorimetry

  • D. Brown
  • T. J. Cole
  • M. J. Dauncey
  • R. W. Marrs
  • P. R. Murgatroyd
Article

Abstract

A method is described for determining rapid changes in gaseous exchange between a subject and the environment, while living in a whole body opencircuit calorimeter. The formulae which must be applied to standard estimates of oxygen consumption are derived the computation of rates of change of gas concentration is discussed the sensitivity of estimated heat production to errors in gas concentration is determined and heat production shown to be largely independent of CO2 measurements; and examples of veritication of the method for known rates of gas injection, and of its use with human subjects, are given. The method is of particular value in assessing the rapid changes in metabolic rate which occur as a result of changes in activity, nutritional state, environmental temperature and the administration of drugs. Such changes are monitored in an unrestrained subject living in a whole-body calorimeter rather than in a subject living with the restrictions imposed by a face-mask or ventilated hood.

Keywords

Fast-response calorimeter Heat production Metabolic rate Oxygen consumption 

List of symbols

E

evaporative heat loss kJ min−1

F

flow rate l min−1 prevailing

f

fractional concentration dimensionless —

H

rate of heat production kJ min−1

P

absolute pressure mm Hg —

R

rate of gas production l min−1 STP

r

calorific value of gas kJl−1 STP

t

time min —

T

absolute temperature Kelvin —

V

volume of calorimeter l —

Ψ

conversion factor to dry STP conditions dimensionless

CO2

carbon dioxide

G

anv gas

i

ingoing

CH4

methane

N2

nitrogen and inert gases

O2

oxygen

o

outgoing

w

water vapour

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References

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Copyright information

© IFMBE 1984

Authors and Affiliations

  • D. Brown
    • 1
  • T. J. Cole
    • 2
  • M. J. Dauncey
    • 3
  • R. W. Marrs
    • 4
  • P. R. Murgatroyd
    • 5
  1. 1.ARC Statistics Group, Department of Applied BrologyUniversity of CambridgeCambridgeEngland
  2. 2.MRC Dunn Nutritional LaboratoryCambridgeEngland
  3. 3.Department of Applied BiologyARC Institute of Animal PhysiologyCambridgeEngland
  4. 4.ARC Statistics Group, Department of Applied BiologyUniversity of CambridgeCambridgeEngland
  5. 5.MRC Dunn Clinical Nutrition CentreCambridgeEngland

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