(XXII, XXIII)
Measurement of basal metabolic
expenditure (BME)
using indirect calorimetry
Calculation of energy expenditure
© Department of Physiology Faculty of Medicine Masaryk University 2016
Basal metabolism
(basal energy expenditure, BEE)
• Energetic expenditure of organism established in defined
(basal) conditions:
• Thermoneutral environment
• 12-18 hours after the last meal containing proteins
• Psychological and social well-being, optimally in the morning
before leaving the bed
Examined persons
Lay down on the examination bed
(to simulate basal conditions)
Actual energy expediture
(AEE)
1) at rest
2) at standing
3) after workload
Determination of energy expediture
1) Measurement:
◦ Direct calorimetry
◦ Indirect calorimetry
2) Calculation
Direct calorimentry
 Works on presumption that
all metabolic actions are
accompanied by heat
production
 Technically demanding
 In practice, often not used
Ice calorimetr – Lavoisier and Laplace, 1782
Zdroj: http://vlp.mpiwg-berlin.mpg.de/vlpimages/images/img10417.jpg
Indirect calorimetry
• Works on presumption that consumption of
oxygen, CO2 production and nitrate
metabolites waste correspond to the
energetic output
• Open or closed cycle setup
• In practicals: closed system setup using Krogh
respirometer
Caloric (energetic) equivalent of oxygen (EE)
• amount of energy released during consumption of 1 L of
oxygen
Constant for mixed diet:
EE = 20,19 kJ/litrO2
Calculation of energy expediture
1) BEE
2) AEE
 According to Harris-Benedict equation
 kcal/day convert into kJ/day (1 kcal = 4,18 kJ)
 May be calculated based on:
◦ BEE
◦ activity factor (AF)
◦ temperature factor (TF)
◦ injury factor (IF)
Protocol
Indirect calorimetry – measurement and calculation of AEE:
1) at rest
2) at standing
3) after workload – steptest
 estimate the oxygen consumption (l/s)
 correct the measured values to 0 C and 101,325 kPa
 calculate AEE (kJ/s, kJ/day)
 explain differences in AEE observed in different conditions
Protocol
Calculation of energy expediture
 Calculate BEE according to Harris-Benedict
 Compare calculated value of BEE with measured value of
AEE at rest
 Explain differences