Measuring energy expenditure in the intensive care unit: a comparison of indirect calorimetry by E-sCOVX and Quark RMR with Deltatrac II in mechanically ventilated critically ill patients

Abstract

BackgroundIndirect calorimetry allows the determination of energy expenditure in critically ill patients by measuring oxygen consumption (VO2) and carbon dioxide production (VCO2). Recent studies have demonstrated variable performance of “breath-by-breath” instruments compared to mixing chamber technology. The aim of this study was to validate two modern devices (E-sCOVX and Quark RMR) against a reference method (Deltatrac II).MethodMeasurements of VO2/VCO2 with the test and reference devices were performed simultaneously over a 20-min period in mechanically ventilated adult intensive care unit patients. Accuracy and precision of instruments were analyzed using Bland-Altman plots.ResultsForty-eight measurements in 22 patients were included for analysis. Both E-sCOVX and Quark RMR overestimated VO2 and VCO2 compared to Deltatrac II, corresponding to a 10 % higher mean resting energy expenditure. Limits of agreement of resting energy expenditure within ±2 standard deviations were ±461 kcal/24 h (±21 % expressed as percentage error) for ΔE-sCOVX–Deltatrac II and ±465 kcal/24 h (±22 %) for ΔQuark RMR–Deltatrac II.ConclusionBoth test devices overestimate VO2 and VCO2 compared to Deltatrac II. The observed limits of agreement are comparable to those commonly accepted in evaluations of circulatory monitoring, and significantly less than results from predictive equations. We hypothesize that the discrepancy between methods is due to patient/ventilator-related factors that affect the synchronization of gas and spirometry waveforms.Trial registrationAustralian New Zealand Clinical Trials Registry, Trial ID ACTRN12615000205538. Date registered 3 March 2015.

Can calculation of energy expenditure based on CO2 measurements replace indirect calorimetry?

“…However, indirect calorimetry is not conducted routinely in most intensive care units (ICU) mainly due to the lack of a reliable indirect calorimeter, and manpower with appropriate expertise to conduct and analyze the results [7]. Recent studies comparing currently available calorimeters have demonstrated that the measured EE is variable from one calorimeter to another [8, 9], although they are still more consistent than the EE calculated from predictive equations [10]. …”

Targeted Full Energy and Protein Delivery in Critically Ill Patients: A Pilot Randomized Controlled Trial (FEED Trial)

“…Body weight, nutrition status, mid upper arm circumference and plasma albumin levels were repeated at discharge from ICU or day 15, whichever came first. In addition, measured energy expenditure (MEE) was assessed by indirect calorimetry using the E‐sCOVX (GE, Helsinki, Finland) monitor . The measurements were carried out within the first 5 days after enrolment, if a trained operator was available, and patients were excluded if they were receiving continuous renal replacement therapy, attached to extracorporeal circulation, had an intercostal catheter with an air leak, or were receiving a fraction of inspired oxygen >0.6 .…”

Assessment of Metabolic and Nutritional Imbalance in Mechanically Ventilated Multiple Trauma Patients: From Molecular to Clinical Outcomes

“…Nevertheless, studies have shown that these equations sometimes give inaccurate answers despite the age, gender, or weight [80] (Table 1). On the one hand, for example, in a study performed to validate the results produced by the two methods, indirect calorimetry was found to have a ±10% degree of error for measured energy expenditure.…”