Reliability of, and Agreement Between, two Breath‐by‐Breath Indirect Calorimeters at Varying Levels of Inspiratory Oxygen

Abstract

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 (FiO2) >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 FiO2. 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 (3cmH2O; positive end‐expiratory pressure: 3cmH2O) at FiO2 of 21%, 50%, 85%, and 21% for 15 minutes at each FiO2. Mean EE, oxygen consumption (VO2), and CO2 production (VCO2) were compared within and between devices across FiO2 levels. Results Device 2 showed within‐device EE significant differences at 21% vs 50% FiO2 and device 1 for VCO2 at 50% vs. 85% FiO2. For all variables, both devices showed reliable measurements at 21% and 50% FiO2, but at 85%, FiO2 bias and limits of agreement increased. Between devices, there were significant differences for EE at both 21% and 85% FiO2 for VO2 and for VCO2 at 85% FiO2. Conclusion Both systems measured EE, VO2, and VCO2 at 21%–85% FiO2 reliably but with bias at 85% FiO2. The devices were in agreement at 21% and 50% FiO2, but further studies need to confirm accuracy at high FiO2.

Comparison of the Beacon and Quark indirect calorimetry devices to measure resting energy expenditure in ventilated ICU patients

“…Poulsen et al compared the Beacon device with another breath-by-breath indirect calorimeter (Ecovx) in healthy subjects (2019). They demonstrated that the Beacon device measured VO 2 , and VCO 2 (and calculated REE) at 21%e85% FiO 2 reliably, but with increasing bias at FiO 2 levels of !85% [25]. We could extend this to the population of critically ill mechanically ventilated patients.…”

“…This Beacon Care system (Mermaid Care Company, Denmark; hereafter called: Beacon) works with any ICU ventilator and requires no installation but only a virtual training of 1 h to use the system [24]. Until now, only one study has been published evaluating reliability and agreement between the Beacon and another indirect calorimetry device, i.e., Ecovx (GE Healthcare, Helsinki, Finland) [25]. It was concluded that Beacon measurements were within-day reliable up to FiO 2 fractions of 0.85.…”

“…Secondary data analysis included the performance of eight frequently used predictive equations compared Beacon and Quark indirect calorimetry. The FAO/WHO/UNU, Harris-Benedict, 25 Predictive equations were adjusted for under-and overweight patients with a Body Mass Index (BMI) of <18.5 or >27 kg/m 2 , respectively. In these cases, weight was adjusted to ideal body weight at a BMI of 18.5 or 27 kg/m 2 .…”

“…Repeating this study in healthy persons will allow evaluating accuracy, bias, and reliability without measuring confounders by disease and sedation. Moreover, as already suggested by Poulsen et al, further studies need to evaluate accuracy, bias and precision at high levels of FiO 2 (!85%) [25]. Finally, validation against next generation indirect calorimeters (Q-NRG) which are currently considered gold standard, is necessary [34].…”

Paramètres dérivés du CO2 pour évaluer l’état hémodynamique chez le malade de réanimation

“…Cependant, la concordance entre les variations de VO 2 par calorimétrie indirecte et celles obtenues par méthode de Fick grâce à un cathéter vasculaire n'est pas bonne [45][46][47]. De plus, la précision de la calorimétrie indirecte est mauvaise chez des patients avec fraction inspirée en oxygène élevée (situation fréquente chez malades les plus graves) [48,49] et invalide en cas de fuite de gaz (trachéotomie, drain thoracique, etc.). La calorimétrie indirecte peut avoir un intérêt hémodynamique grâce aux mesures répétées du QR, permettant éventuellement d'évaluer l'état d'hypoxie tissulaire, comme lors de la titration d'un support inotrope [50].…”