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Determination of metabolic monitor errors and precision under clinical conditions
J A Melendez1, M Veronesi, R Barrera
1Department of Anesthesiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York 10021, USA.
Background & Aims:
Metabolic monitoring devices used in the critical care setting are subject to a range of conditions that may compromise their accuracy. We sought to investigate the error and precision of the Deltatrac metabolic monitor under these conditions.
Methods:
A modified version of the funnel burner, described by Miodownik et al. (8), was ventilated by a mechanical ventilator. This was used to examine the performance of the Deltatrac metabolic monitor over a wide range of inspired oxygen concentrations, minute ventilation, and positive end expiratory pressure at different levels of oxygen consumption and carbon dioxide production.
Results:
The Deltatrac measured V(O(2)) with a mean error+/-precision of 9.4%+/-19.5% (range, 9.3%+/-1.9%-72.6%+/-13.6%). The mean V(CO(2)) error+/-precision was 1.2%+/-3.1% (range-2.0%+/-1.2%-5.4%+/-3.1%). Error was significantly affected by oxygen concentration and minute ventilation but was largely independent of positive and expiratory pressure.
Conclusions:
The methodology of Miodownik et al. permits the expression of metabolic device errors over a wide range of simulated clinical conditions.