SPECIALTIES : Pulmonology

The tremoflo® Airwave Oscillometry System (AOS) has revolutionized the Forced Oscillation Technique (FOT) by using a vibrating mesh to superimpose a gentle oscillatory pressure and flow wave onto the patient’s spontaneous breathing to measure respiratory impedance as lung resistance (R) and reactance (X). The resulting waveforms from the tremoflo® AOS provide measurements of the mechanical properties of the large central and smaller peripheral airways. This unique information is clinically valuable and complementary to Spirometry.


Obstructive pulmonary diseases such as asthma and COPD are increasingly recognized to originate in the “small airways”. Early obstructions in these peripheral airways are oft en not measurable only by spirometry and therefore risk going undetected. Oscillometry has been shown to be sensitive to changes in the small airways.

Consequently, oscillometry provides unique and valuable information regarding peripheral lung function over and above spirometry, which translates into better patient outcomes.

Optimal: combination of both:

As the study by the Scottish Centre for Respiratory Research (published in 2022) shows, it is best to combine the advantages of spirometry and oscillometry measurements. This combination allows a complete characterization of airflow limitation in moderate to severe asthma.


Tremoflo® measurements are fast & easy.
The patient just breathes quietly.
To assess respiratory function, the tremoflo® adds a gentle oscillatory wave to the patient’s regular, quiet breathing. A short measurement duration of only 20 seconds allows three manoeuvres within a couple of minutes, even in patients who have difficulty performing spirometry.


Summary of clinician interpretations per published studies 1-5
A pair of curves calculated from the raw data reflects the mechanical properties of the respiratory system in characteristic patterns. Several key outcome parameters are then derived from these curves.

Benefits at a glance

  • No active cooperation of patient required – advantages for adults and pediatrics
  • No specific manoeuvre needed – just tidal breathing
  • Reversability and provocation testing
  • Measurement of the small airways, captures the lung periphery
  • Quick and easy to perform
  • Easy daily calibration, in under 30 seconds
  • Compact, portable device

Advantages for children and elderly

Spirometry tests are often stressful and depend on patient cooperation and maximal effort. The elderly and young children in particular have difficulties in understanding and following the instructions.

As oscillometry is performed in tidal breathing, neither skilled coaching by the operator nor patient effort is required to obtain a successful test.

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