Accuracy of Oxygen Consumption and Carbon Dioxide Elimination Measurements in 2 Breath-by-Breath Devices

Respir Care. 2017 Apr;62(4):475-480. doi: 10.4187/respcare.05115. Epub 2017 Jan 17.

Abstract

Background: Although accurate quantification of oxygen consumption (V̇O2 ) and carbon dioxide elimination (V̇CO2 ) provides important insights into a patient's nutritional and hemodynamic status, few devices exist to accurately measure these parameters in children. Therefore, we assessed the accuracy and agreement of 2 devices currently on the market using a pediatric in vitro model of gas exchange.

Methods: We utilized a Huszczuk simulation model, which simulates oxygen consumption and carbon dioxide production using gas dilution, to examine the accuracy of two FDA-cleared respiratory modules (E-COVX and E-sCAiOVX-00). V̇O2 and V̇CO2 were set at 20, 40, 60, and 100 mL/min, ranges typical for infant and pediatric patients. Bland-Altman analysis was used to calculate the bias and limits of agreement of each device relative to simulated values for V̇O2 and V̇CO2 .

Results: The E-COVX mean percentage bias (limits of agreement) was -26.3% (-36.1 to -16.6%) and -39.3% (-47.5 to -31.1%) for V̇O2 and V̇CO2 , respectively. The mean bias (limits of agreement) for the E-aCAiOVX-00 was -0.5% (-13.3 to 12.3%) and -6.0% (-13.8 to 1.7%) for V̇O2 and V̇CO2 , respectively.

Conclusions: The E-COVX demonstrated bias and limits of agreement that were not clinically acceptable; therefore, application of this module to pediatric patients would not be recommended. The new module, E-sCAiOVX, demonstrated acceptable bias and limits of agreement for the V̇O2 and V̇CO2 in the range 40-100 mL/min (which corresponds to patients in the range of ∼5-16 kg).

Keywords: accuracy; carbon dioxide elimination; gas exchange; indirect calorimetry; oxygen consumption.

Publication types

  • Comparative Study

MeSH terms

  • Breath Tests / instrumentation*
  • Capnography / instrumentation*
  • Carbon Dioxide / analysis*
  • Child
  • Computer Simulation
  • Humans
  • Infant
  • Oxygen Consumption*
  • Reproducibility of Results
  • Respiration, Artificial / instrumentation*

Substances

  • Carbon Dioxide