While running a spirometry test in Medikro Spirometry, an issue can occur where an expiration maneuver shows as an inspiration on the graph, or an inspiration maneuver shows as an expiration on the graph (the results appear inverted/inverse).
You may observe the behaviour when blowing in the mouthpiece. The expected behaviour is that an expiration registers a positive flow value on the y-axis of the graph, and an inspiration registers a negative value on the y-axis of the graph.
Press the Show Flow-Volume Curves button to show the entire unfiltered data recorded in the test, and will make it easier to confirm if the results are inverted.
This image shows an inverted result, where the exhale has shown a negative value.
Check that there is no moisture build up inside the mouthpiece. Heavy condensation iside the mouthpiece has been known to gather inside the mouthpiece which partially blocks the tiny holes where the pressure inside the mouthpiece is transferred to the pressure tube.
Location of tiny holes, when covered in mousture the result may invert until wiped/dried.
If this occurs, a tissue can be used to wipe the inside of the mouthpiece, or if very damp, a new moutpiece connected and the old one discarded. Please be sure to follow the usual infection control/health and safety protocols when doing this.
Another 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.
Pressure tube seated in the mouthpiece connector
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.
