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62/148 REF C04717-02-91 Q-NRG User Manual, Edition 4.2
Chapter 3 - Q-NRG Operation COSMED srl
Recommendations During Testing
You can achieve the maximal reliability and accuracy of measurements following the rules described below:
• Have the device properly calibrated according to instructions.
• Have the device regularly maintained according to instructions.
• Have residual battery capacity adequate to complete a test.
• Position the Q-NRG correctly to avoid reading of possibly contaminated air.
Q-NRG Placement
The Q-NRG has an air intake on the back of the device for air cooling and automatic calibration purpose; the
following recommendations are common among all test modalities. When installing, make sure there is adequate
clearance area of air intake to ensure optimal performance of the unit; The Q-NRG shall NOT be positioned anyway
allowing potential accumulation of diluted or ventilator exhausted gas (e.g. exhaust port of ventilator), a minimum
25 cm around the unit and air intake should be clear.
>25 cm /10”
>25 cm /10”
VENTILATOR Mode
• To avoid unnecessary patient discomfort or aerosol spreading when acting on patient circuit, consider
performing the measurement whenever the patient filter is changed according to your ICU policy.
•
Avoid changing FiO2 settings on ventilator during a measurement.
• FiO2 during the selected averaging interval shall be constant.
• Some ventilator may provide significant unstable FiO2 profile during inhalation, affecting the accuracy of
measurements. A simple measure that decreases fluctuation is to place the FiO2 adapter at the outlet of
the humidifier (if present) or after the inspiratory filter placed at the inspiratory port of the ventilator.
• Ventilator modality must guarantee that measured inspiratory and expiratory volumes match patient’s
inhaled and exhaled volumes (e.g. face mask with controlled leaks are not compatible with measurements)
• Any additional dead space (i.e. in addition to the parts recommended by COSMED) placed between the
connection for sampling line on the filter and the patient circuit Y-connector (or similar) slightly affect
results accuracy. It is estimated that an additional dead space of 15 mL can generate an underestimation of
approximately 3% on the REE measurement (the error increases with increasing dead space and respiratory
frequency). Any dead space must be primarily addressed in terms of patient safety and/or ventilatory
management (see also “Precautions/Contraindications”).