If the Expiratory Flow has accidentally been recorded to be a positive flow, you will not get correctly calculated Metabolic Parameters in the Metabolic Module, as the Metabolic Module is looking for a negative deflection by default. There are 2 ways to correct this issue post-recording:
1. If only interested in the parameters calculated by the Metabolic Module, you can correct the calculation by going to:
Metabolic | Metabolic Settings | Environment, and change the Measuring section from Expired to Inspired.
2. You can use Arithmetic to invert the signal and values to give a negative deflection. To do this, use a spare Channel in LabChart and use the following Arithmetic calculation:
ChX*-1
Where X is the Channel containing the original Spirometry Flow Data. It's important to also ensure you change the units to L/s, as the Arithmetic Calculation will default to Volts:
This approach is ideal if you need to export the raw data to a 3rd party Metabolic Analysis program.
For further technical assistance with this or any other issue, please contact ADInstruments Technical Support by clicking HERE.