Oscillometry System
Test pulmonary function with minimal patient effort

Airwave oscillometry*

The tremoflo® Airwave Oscillometry System (AOS) is a portable medical device intended to monitor lung function and assess human respiratory diseases such as asthma and COPD in adults and children.

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.

* Legal manufacturer: THORASYS Thoracic Medical Systems Inc.

Tremoflo Oscillometry

Just tidal breathing

No artificial breathing manoeuvre needed, no rough impulses applied, measuring with natural tidal breathing

Easy to use & very fast

Intelligent software, little instruction time needed, calibration verified for many measurements per day

Reversability & provocation testing

Templates for provocation and reversibility testing are excellent for identifying pre/post changes when using AOS

Suitable for geriatric and pediatric use

The method works with minimal active patient cooperation. Allowing to measure in a wide spectrum of patients, from pre-school children to elderly population

Semi-automatic calibration verification

Daily verification (30 s) of device ensures accurate measurements and long-term stability

Compact and portable

Not only suitable for stationary, but also light enough for mobile use

Spirometry and oscillometry

Spirometer and Oscillometer with PFT

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 airfl ow 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.

Characteristic patterns

Benefits at a glance

Advantages for children and elderly

Child uses tremoflo

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.

1 Hirsh et al., AAAAI 2011   2 Usmani et al., RESPIRATORY MEDICINE 2016   3 Al-Alwan et al., AJRCCM 2014   4 Galant et al., AAAAI 2017    5 Johnson et al., THORAX 2007