The effects of a fluctuating Fio2 on metabolic measurements in mechanically ventilated patients

An in vitro validation of a commercially available metabolic cart using pediatric ventilator volumes

“…Fluctuation of the F i,O 2 from the blender within the ventilator or breathto-breath variation may further adversely affect results. 7 Because of the variability of results that were encountered with small tidal volumes, increased F i,O 2 , and elevated PEEP, the manufacturer of the equipment was contacted and the equipment was examined to determine if it was functioning properly. Testing done by a company representative revealed that the voltmeter for the mass flow anemometer never returned to zero at the end of a 50-mL V t .…”

“…5 Regardless of the application, gas exchange measurements may be difficult to perform accurately, particularly in the mechanically ventilated patient. Leaks in the collection system or around the endotracheal tube, 6 instability of inspired O 2 , 7 and failure to maintain a resting state may prevent accurate measurement of oxygen consumption (VЈ O 2 ) and carbon dioxide production (VЈ CO 2 ). When these variables are controlled in the mechanically ventilated patient, the metabolic monitoring device must be highly accurate over a wide range of ventilator settings to provide valid, and therefore meaningful, results.…”

Different dosages of dobutamine in septic shock patients: determining oxygen consumption with a metabolic monitor integrated in a ventilator

“…These results were confirmed under clinical conditions [14,15]. In critically ill patients requiring mechanical ventilation, this method has some limitations: results can be affected by changes of the inspired oxygen fraction (FIO 2 ), by changes of pressure or by gas leaks in the ventilatory system [16,17]. A high FIO 2 may lead to errors due to the limited ability of O 2 sensors to discriminate high O 2 concentrations [15,18].…”

Comparison between the Datex-Ohmeda M-COVX metabolic monitor and the Deltatrac II in mechanically ventilated patients

“…Clinical applications vary from the assessment of energy expenditure to the comprehensive analysis of ventilation and oxygen transport in critically ill patients. The accurate measurement of respiratory gas exchange in the critically ill mechanically ventilated patient poses several problems that include high-inspired oxygen concentrations, leaks resulting from positive airway pressures, and humidity [2,3,4,5,6,7].…”