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Reliability of, and Agreement Between, two Breath‐by‐Breath Indirect Calorimeters at Varying Levels of Inspiratory Oxygen
Author(s) -
Poulsen Mathias Krogh,
Thomsen Lars Pilegaard,
Kjærgaard Søren,
Rees Stephen Edward,
Karbing Dan Stieper
Publication year - 2019
Publication title -
nutrition in clinical practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 71
eISSN - 1941-2452
pISSN - 0884-5336
DOI - 10.1002/ncp.10250
Subject(s) - medicine , anesthesia , limits of agreement , oxygen , reliability (semiconductor) , nuclear medicine , power (physics) , chemistry , physics , organic chemistry , quantum mechanics
Background Indirect calorimetry (IC) is considered the accurate way of measuring energy expenditure (EE). IC devices often apply the Haldane transformation, introducing errors at inspiratory oxygen fraction (FiO 2 ) >60%. The aim was to assess measurement reliability and agreement between an unevaluated IC (device 2) (Beacon Caresystem, Mermaid Care A/S, Noerresundby, Denmark) not using Haldane transformation and an IC that does (device 1) (Ecovx, GE, Helsinki, Finland) at varying FiO 2 . Methods Twenty healthy male subjects participated, with 16 completing the study (33 ± 9 years, 83.3 ± 16 kg, 1.83 ± 0.08 m). Subjects were mechanically ventilated in pressure support (3cmH 2 O; positive end‐expiratory pressure: 3cmH 2 O) at FiO 2 of 21%, 50%, 85%, and 21% for 15 minutes at each FiO 2 . Mean EE, oxygen consumption (VO 2 ), and CO 2 production (VCO 2 ) were compared within and between devices across FiO 2 levels. Results Device 2 showed within‐device EE significant differences at 21% vs 50% FiO 2 and device 1 for VCO 2 at 50% vs. 85% FiO 2 . For all variables, both devices showed reliable measurements at 21% and 50% FiO 2 , but at 85%, FiO 2 bias and limits of agreement increased. Between devices, there were significant differences for EE at both 21% and 85% FiO 2 for VO 2 and for VCO 2 at 85% FiO 2 . Conclusion Both systems measured EE, VO 2 , and VCO 2 at 21%–85% FiO 2 reliably but with bias at 85% FiO 2 . The devices were in agreement at 21% and 50% FiO 2 , but further studies need to confirm accuracy at high FiO 2 .