Abstract
The measurement of whole body heat loss in humans and the performance characteristics of a modified Snellen whole body air calorimeter are described. Modifications included the location of the calorimeter in a pressurized room, control of operating temperature over a range of − 15 to + 35°C, control of ambient relative humidity over a range of 20–65%, incorporation of an air mass flow measuring system to provide real time measurement of air mass flow through the calorimeter, incorporation of a constant load ‘eddy current’ resistance ergometer and an open circuit, expired gas analysis calorimetry system. The performance of the calorimeter is a function of the sensitivity, precision, accuracy and response time characteristics of the fundamental measurement systems including: air mass flow; thermometry and hygrometry. Calibration experiments included a calibration of the air mass flow sensor, the response of the thermometric measurement system for dry heat loss and the response of the hygrometric measurement system for evaporative heat loss. The air mass flow system was evaluated using standard differential temperature procedures to demonstrate linearity and sensitivity of the device. A novel procedure based on differential hygrometry was developed to ascertain the absolute calibration of air mass flow by resolving the unique system coefficient K. The results of the hygrometric calibration demonstrate the air mass flow response of the system is linear over the range of air mass flows from 6 to 15 kg min−1. R 2 was 0.995. The average half response time (tR50) was 14.5 ± 2.1 s. Similarly the results of the thermometric calibration demonstrate that the response of the apparatus is linear over the range of power input measured (coefficient of linearity R 2 = 0.9997) with a precision of 0.72 W and an accuracy to within 0.36 W. The average (tR50) over all conditions was 6.0 ± 1.9 min. In summary, modifications brought to the Snellen calorimeter have significantly improved the precision, accuracy and response time characteristics of the previous system while extending its operating range.
References
Dauncey MJ, Murgatroyd PR, Cole TJ (1978) A human calorimeter for the direct and indirect measurement of 24 h energy expenditure. Br J Nutr 39:557–566
DuBois D, DuBois EF (1916) A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 17:863–871
Jacobsen S, Johansen O, Garby L (1985) A 24-m3 direct heat-sink calorimeter with on-line data acquisition, processing, and control. Am J Physiol 249:E416–E432
Seale JL, Rumpler WV, Moe PW (1991) Description of a direct–indirect room-sized calorimeter. Am J Physiol 260:E306–E320
Snellen JW, Chang KS, Smith W (1983) Technical description and performance characteristics of a human whole-body calorimeter. Med Biol Eng Comput 21:9–20
Spinnler G, Jequier E, Favre R, Dolivo M, Vannotti A (1973) Human calorimeter with a new type of gradient layer. J Appl Physiol 35:158–165
Vallerand AL, Savourey G, Hanniquet AM, Bittel JH (1992) How should body heat storage be determined in humans: by thermometry or calorimetry? Eur J Appl Physiol Occup Physiol 65:286–294
Visser J, Hodgson T (1960) The design of a human calorimeter for the determination of body heat storage. S Afr Mech Eng 9:243–260
Webb P (1985) Human calorimeters. Praeger, New York
Webster JD, Welsh G, Pacy P, Garrow JS (1986) Description of a human direct calorimeter, with a note on the energy cost of clerical work. Br J Nutr 55:1–6
Widner AE, Fehlmann R, Rehwald W (1982) A calibration system for calorimetric mass flow devices. J Phys E Sci Instrum 15:213–220
Acknowledgments
This research was supported by the US Army Medical Research Program, Military Relevant Disease Management (funding support held by Dr. G.P. Kenny).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Reardon, F.D., Leppik, K.E., Wegmann, R. et al. The Snellen human calorimeter revisited, re-engineered and upgraded: design and performance characteristics. Med Bio Eng Comput 44, 721–728 (2006). https://doi.org/10.1007/s11517-006-0086-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11517-006-0086-5