In the back of the Trilogy Evo ventilator, you can fit a FiO₂ oxygen cell that tells you how much oxygen your patient is receiving through the circuit.

The oxygen cell does not come pre-installed into the machine. Installation involves the following steps:

1. Remove the panel at the back of the machine using a 6-point star headed screwdriver.
2. Screw the base of the oxygen cell into the housing of the machine.
3. Attach the electronic sensor cable.
4. Replace the cover and re-screw the two screws.

On installation of a new oxygen cell, the machine should be calibrated to the room air (FiO₂ 21%):

1. Turn on the device and attach one end of the tubing to the output.
2. Choose the spanner option, select ‘calibration and set-up’, and select ‘O₂ sensor calibration’.
3. Follow the instructions on the screen to start calibration.
4. After the initial step of calibration, occlude the tubing for the second step of calibration.
5. Once you get notification that the calibration has passed, the oxygen cell is ready for use and you can return to the homepage of the ventilator.