Abstract
PURPOSE: We present a methodological overview of a respiration chamber at the Experimental and Clinical Research Center in Berlin, Germany. Since 2010, we investigated 750 healthy subjects and patients with various diseases. We routinely measure resting energy expenditure (REE), dietary-induced thermogenesis, and activity energy expenditure. METHODS: The chamber is a pull calorimeter with a total volume of 11,000 L. The majority of measurements is done with a flow rate of 120 L/min, yielding a favorable time constant of 1.53 h. The gas analysis system consists of two paramagnetic O(2) sensors and two infrared CO(2) sensors, one for incoming and one for outgoing air samples. O(2) and CO(2) sensors are calibrated simultaneously before each measurement with a 6 min calibration routine. To verify the accuracy of the whole the calorimetric system, it is validated every 2 weeks by 2 h acetone burning tests. RESULTS: Validation factors (calculated/measured) of 20 representative 2 h acetone burning tests were 1.03 ± 0.03 for [Formula: see text], 1.02 ± 0.02 for [Formula: see text], 0.99 ± 0.02 for RER, and 1.03 ± 0.03 for EE. Four repeated 60 min REE measurements of a healthy woman showed variabilities of 231.9 ± 4.8 ml/min for [Formula: see text] (CV 2.1%), 166.0 ± 6.3 ml/min for [Formula: see text] (CV 3.8%), 0.73 ± 0.03 for RER (CV 4.6%), and 4.55 ± 0.07 kJ/min for EE (CV 1.6%). CONCLUSIONS: The data presented show that our respiration chamber produces precise and valid EE measurements with an exceptionally fast responsiveness.