While running a spirometry test in Medikro Spirometry, an error can occur where an exhale maneuver shows as an inhale on the graph, or an inhale maneuver shows as an exhale on the graph. The results are inverted.
You may observe the behaviour when blowing in the mouthpiece. The expected behaviour is that an exhale registers a positive flow value on the y-axis of the graph, and an inhale registers a negative value on the y-axis of the graph. When this error occurs, the results will be flipped.
Once you have recorded a test, it may be difficult to see the full flow-volume curve. Medikro filters the data depending on the test type. So if you perform an FVC test, only the exhale data is shown.
Press the Show Flow-Volume Curves button to show the entire data for the test session. This will allow you to see the unfiltered data recorded in the test, and will make it easier to confirm if the results are inverted.
The likely cause of inverted results is that the pressure tube has been flipped at the mouthpiece connector. To fix the inverted results, we must reseat the pressure tube in the correct orientation as it is likely around the wrong way.
1. Gently disconnect the pressure tube from the mouthpiece connector.
2. Note that the pressure tube has two holes in it. Observe the nozzle on the mouthpiece connector; take note of the side of the pressure tube the nozzle was connected to.
3. Flip the pressure tube and seat the opposite hole in the tube onto the nozzle on the mouthpiece connector.
4. Connect the complete tube assembly to the Medikro spirometer and a mouthpiece. Do a test in the software to confirm that an exhale maneuver registers a positive flow value, and an inhale maneuver registers a negative flow value.
If you are still experiencing odd results, confirm that the tube is properly seated on the Medikro spirometer. The connector orientation must be correct when sliding the connector onto the device so that the holes and tabs line up properly.