Steady-State And Duration Of The Indirect Calorimetry Measurement In Healthy Subjects

Abstract

Provide an optimized nutrition is important goal for clinical area. Increasing evidence indicates that energy imbalances that occur as a result of inaccurate resting energy prediction equations put patients at risk for underfeeding and overfeeding and can lead to unexpected results. Longer periods of measurements have been recommended for metabolically unstable patients to identify the steady state (SS) of the resting energy expenditure (REE) using indirect calorimetry (IC). Thus, there is still no consensus about the shortest SS and duration using IC measurement with healthy. PURPOSE: i) to identify the shortest SS of the REE during 30 min (REE30) using IC measurement in healthy subjects; ii) to suggest a short duration of IC measurement in healthy subjects. METHODS: Thirty-nine healthy subjects (27 men and 12 women) aged 18 to 31 years were recruited for the study. The subjects were assessed in fasting and in the morning. REE was obtained by continuous gas-exchange measurements during REE30 by IC. Coefficient of variation (CV%) was performed to identify the SS in each 5-min partial time (REE5) of the total REE30. Friedman and Wilcoxon paired test were used to compare each REE5 and Bland-Altman test to verify the agreement between the shortest duration with REE30 of IC measurement. RESULTS: The CV% of the 1st/REE5 (15.5 [3.4 to 46.5%) was significantly higher (p < 0.001) than all others REE5 (2nd/REE5: 6.3 [1.9 to 15.7%]; 3rd/REE5: 6.3 [2.8 to 30.9%]; 4th/REE5: 6.3 [0.8 to 17.2%]; 5th/REE5: 6.3 [1.7 to 32.4%] and 6th/REE5: 7.1 [2.8 to 20.4%]). The 2nd/REE5 explained 91% of the total measurement during REE30 by IC and Bland-Altman shown -114.128 to 139.974 kcal/day of limits of agreement (95%) and 12.92 ± 64.82 kcal/day of bias. CONCLUSION: The shortest SS was identified in the 2nd/REE5 and can be used to obtain the REE (kcal/day) explaining 91% of the total REE30 measurement by IC. The study suggests a duration of 10-min of IC measurement discarding the 1st/REE5 and using the REE average of the 2nd/REE5.