Plethysmography Procedure

Preparation

• Ensure the patient is seated in the plethysmography box.
• Attach a nose clip to the patient.
• Have the patient place their hands on their cheeks.
• Close the door of the box.
• Direct the patient to breathe normally.

Equilibrating Box Pressure

• Close the box vent, then open and close it again.
• Use the box vent control on the top left of the screen to equalize the pressure inside the box.

TGV (Thoracic Gas Volume) Test

• Ensure the patient is breathing within the green stability area on the quality control gauge.
• Select TGV on the device.
• Collect at least four stable tidal breaths.
• At the end of a breath, press the space bar to start collecting closed shutter pants.
• Guide the panting rate using the metronome on the quality graph.
• Instruct the patient to inhale and exhale maximally.
• Encourage them to keep exhaling until they feel they have completely emptied their lungs.
• Press the space bar to end the test.

Quality Control

• At the end of the test, the quality graph will display the closed panting rate.
• If in the correct range, the indicator will be green.
• Any errors will be displayed centrally.

Alternative Test: Nitrogen Washout

• Suggested if the patient cannot perform plethysmography.

Airways Resistance and Thoracic Gas Volume

• Similar setup as TGV with nose clip and hand placement.
• Use the same procedures to equilibrate the pressure in the box.

RAW (Airways Resistance) Test

• Ensure the patient is breathing within the green stability area.
• Select RAW on the device.
• Collect at least four stable tidal breaths.
• At the end of a breath, press the space bar to collect open shutter pants and guide the panting rate with the metronome.
• Collect four closed shutter pants using the metronome for guidance again.
• Press the space bar to end the test.

Performing Tests Together

• It is often challenging to get an acceptable switch when performing airways resistance and thoracic gas volume together.
• It is recommended to perform TGV separately for accuracy.

Adjustments

• Double-click on the TGV RAW graph to adjust the settings.
• Choose graph type: close for TGV, open for RAW.
• Adjust the graph's angle and position.
• Use "Show Guides" to place parallel lines on the graph.
• Use "Show Open" to display open shutter pants.
• Choose to show four superimposed breaths or four separate breaths.