[Initial clinical experiences with the S & W Kaloximet, a device for measuring oxygen consumption in anesthesia and...

The system is based on the principle of indirect calorimetry in the closed-circuit rebreathing system with CO2 absorber. The decrease in circulating gas volume (i.e. O2 uptake) is measured by an ultrasonic technique and a microprocessor controls the replenishment of the system with oxygen from an external O2 supply. The Kaloximet can be used to measure the O2 uptake of both spontaneously breathing and mechanically ventilated patients. In ventilator patients, the system works according to the bag-in-bottle principle. The O2 consumption is measured as the average of at least 50 breaths and then this value is used to calculate the resting energy expenditure. The estimated value of the respiratory quotient is entered on the keyboard, either before or after measurement. We tested the accuracy of the system in 48 measurements of O2 consumption using the Kaloximet and the Fick principle (cardiac output x arteriovenous O2-content difference) simultaneously. We found a mean difference of 5.6% and a positive correlation (r = 0.97). Our results indicate that the Kaloximet is suitable for measurements of O2-consumption, especially in ICU patients. Intraoperatively, it can be used only in the absence of inhalation anesthetics.