Evaluation du calculateur de métabolisme Engstrom

Abstract

The Engstrom Metabolic Computer (EMC), in association with the Erica Ventilator, uses indirect calorimetry to carry out continuous on-line gas exchange measurements. A laboratory assessment of the different parts of this equipments is described. The variability of Fio 2 was less than 0.05. The accuracy and stability of the inspiratory flowmeter were only slightly modified by changes in the I/E ratio and gas flow rates. The overestimation of flow on increasing Fio 2 was taken into account by the computer. The hygrometry of inspiratory and expiratory air samples reached that of room air, with an absence of saturation during prolonged measurements. The CO 2 analyser also showed a good stability. The accuracy of the oxygen cell needed to be checked periodically. A global evaluation was carried out using Damask's method : a lung model was used into which CO 2 and N 2 were insufflated at precise rates to simulate CO 2 production and O 2 consumption. The measured respiratory quotient was also compared with the known RQ of burning methanol. The difference between measured and real values was less than 5%. Therefore, it was concluded that the EMC was reliable for indirect calorimetry measurements.