Determination of metabolic monitor errors and precision under clinical conditions.
OBJECTIVE
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.
Melendez
J A
JA
Department of Anesthesiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York 10021, USA.
Veronesi
M
M
Barrera
R
R
Ferri
E
E
Miodownik
S
S
D002153:Calorimetry, Indirect; D002245:Carbon Dioxide / Q000032:analysis*; D003422:Critical Care; D006801:Humans; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D010100:Oxygen / Q000032:analysis*; D010101:Oxygen Consumption; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012122:Ventilators, Mechanical
D002245:Carbon Dioxide; D010100:Oxygen