Forced oscillation technique (FOT) is a reliable method in assessing bronchial hyperresponsiveness and both its sensitivity and minimal patient effort makes it an ideal lung function test for epidemiological and field studies, according to the ERJ.[1]

For a better understanding of the technology and its role in assessing pulmonary function, RT spoke with Roberto “Roby” Perissin, vice president of FOT and Asthma Diagnostics Business Development, MGC Diagnostics.

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RT: Why is forced oscillation technique a reliable method in assessing bronchial hyperresponsiveness?

Perissin: FOT, a widely validated method since the 1950s that, besides other advantages, has proven to be more sensitive than forced spirometry especially with respect to small airways obstruction.

The FOT test, being based on simple tidal breathing and not requiring a deep inhalation, also proven to affect bronchial tone and therefore adding a “bias” in bronchial hyperresponsiveness, makes the test simple and repeatable during a pre-post bronchodilator but also on bronchial challenge testing, tedious and difficult test for the patient and the operator, that can be performed in less time and easier for the patient. It’s been also demonstrated  that with FOT “lower concentrations of methacholine were needed for a positive test.”

RT: What FOT product does MGC offer?

Perissin: MGCD has integrated in its full PFT line a unique new product based on the traditional, established FOT method  but with 2018’ technology and algorithms, the Resmon Pro Full, the result of more than 15 years of research conducted by a premier medical bioengineering team at the Politecnico di Milano University in cooperation with European, US and Australian clinical and research laboratories. It is an FDA cleared and CE approved product now sold worldwide, with extensive bibliography of publications, used in children to adults, even severely obstructed.

Resmon Pro is the only FOT device featuring a choice of FOT measurement modes including the single frequency mode suitable for very young children and very obstructed patients.

Using a “Within Breath” analysis of breathing patterns at a fast sampling frequency, with a validated real-time “accepted breaths” algorithm and reject of bad, non-physiological breaths, the Resmon Pro Full allows one operator only, to focus on the patient during the test. The subject has simply to breathe normally, all the non-acceptable breaths automatically are discarded, once the test reaches the desired, set number of accepted breaths (ie 10 or 15 or more) the measurement stops and the results are calculated and displayed.

Because of this feature, Resmon Pro Full FOT testing is now even less patient and operator dependent than in the past, it is used in asthma, COPD and evaluation of airways clearance techniques.

Among several unique features and in addition to the “within breath” measurement of all the INSP, EXP and TOTAL parameters, Resmon Pro features a Breath-by-breath detection of tidal Expiratory Flow Limitation (or EFL, patented) with an index that can be used during pre and post bronchodilator testing or airways clearance evaluation sessions but also during COPD therapy evaluation and CF treatment.

RT: are there things that can improve and make the testing even more seamless?

Perissin: Test evaluation. Resmon Pro Full with its new approach to FOT and unique useful features has been contributing to make FOT testing, for the first time, accessible to many more than in the past in daily clinical applications with a novel easy pathway of “test evaluation” that all the clinical personnel understand and now can use in the evaluation of presence and localization of obstruction but also determination of tidal EFL (Expiratory Flow Limitation), a very actual and serious issue in respiratory diseases management.

Use in COPD exacerbation prediction. A novel product, based on Resmon Pro (validation study just published on the AJRCCM) marketed only in Europe and not available in the US, provides now a “service” at home for COPD patients that can predict exacerbations with savings on re-hospitalization costs and frequency with results monitored by the hospital lab. This proved the accuracy in early detection of exacerbations but also patient independency of this FOT test, performed at home by the unattended patient.

FOT to help quantify the disease’ degree. FOT testing will be further improved in its use when there will be the possibility to “quantify” the degree of the obstruction (mild, moderate and severe) through FOT parameters, as it is done with the FEV1/FVC of forced spirometry, currently the “gold standard”. MGCD is patiently working with several world class centers in different international clinical studies to collect data on normal subjects but also on different degree of obstructive diseases, studies that may add in the near future data and understanding of the disease categorization so that the Resmon FOT could be used in conjunction with forced spirometry but in many cases instead, in the future.

New applications in asthma management: FOT (obstruction)  and FeNO (inflammation). Integrating results of FOT with other pulmonary tests is also something that will complete the picture of respiratory diseases evaluation, such as combining FOT with FeNO (exhaled nitric oxide) in Asthma management as MGCD is doing internationally with another nonavailable in the US “combo” system that is gaining acceptance outside the US. RT