title: Influence of ventilatory settings on indirect calorimetry in mechanically ventilated patients.
abstract: With the aim to assess metabolic monitor's suitability to the use in mechanically ventilated patients, a method, based on the comparison between the measurements performed by the monitor and the ventilator, is here described. In particular, the effects of positive end-expiratory pressure and oxygen inspiratory fraction (FiO(2)) on the metabolic measurements in presence of bias flow are investigated. In this study a metabolic monitor is used to estimate the energy expenditure of 10 mechanically ventilated cardiosurgical patients at different positive end-expiratory pressure, FiO(2) and two different modes of ventilation, with bias flow. The influence of the ventilatory settings on the parameters measured by the monitor is here quantified: a slight decrease of respiratory quotient and a slight increase of resting energy expenditure are observed with the increase of FiO(2). This study shows a good agreement between the measurements of the two devices: FiO(2), expiratory volume (mean difference lower than 3%), and respiratory frequency (mean difference lower than 1%). This also demonstrates the capability of the metabolic monitor to reject the effect of the bias flow.
authors.affiliation: Unit of Measurements and Biomedical Instrumentation, Center for Integrated Research, Università Campus Bio-Medico di Roma, 200128 Rome, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cecchini
authors.forename: E
authors.initials: E
authors.lastname: Schena
authors.forename: R
authors.initials: R
authors.lastname: Cuttone
authors.forename: M
authors.initials: M
authors.lastname: Carassiti
authors.forename: S
authors.initials: S
authors.lastname: Silvestri
mesh_terms: D001944:Breath Tests / Q000295:instrumentation*; D002151:Calorimetry / Q000295:instrumentation* / Q000379:methods; D017076:Computer-Aided Design; D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008168:Lung / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D011175:Positive-Pressure Respiration / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology*; D012680:Sensitivity and Specificity