Forced Oscillation Technique


In pre-school children with Asthma, cystic fibrosis (CF) and other respiratory problems clinical teams struggle to
measure the progression of their lung disease objectively. Identifying damage early may allow the clinicians to
treat individual patients appropriately and hopefully prevent deterioration.

The forced oscillation technique (FOT) is a non-invasive method to measure the mechanical properties of the lung
and airways during normal tidal breathing. In addition to measuring total impedance (resistance and reactance) the
Resmon Pro can measure limitation to airflow during expiration which is a hallmark of airway obstruction.  This
technology allows for evaluating severity of expiratory flow limitation (EFL) during quiet breathing.  Using FOT,
presence, severity and reversibility can be studied.  It can be used to test patients before and after treatment to check
the effectiveness of the drugs being administered.

How does it differ from existing equipment?

Almost all respiratory physicians, nurses and physiologists will use a spirometer to measure airflow obstruction and
vital capacity. These devices, however, require a large effort on the part of the patient and a high degree of cooperation.
In contrast, the Resmon Pro makes its measurements from ten normal breaths without any coordination. This means
that very young children and those too unwell to do a spirometry test can usually manage to breathe ten breaths into
the Resmon Pro. It is also sensitive enough to measure patients whose asthma might only occur during exercise and
might not be detected by a spirometry test.  These parameters are becoming standard in other centres of paediatric
respiratory excellence (such as the Guy’s Hospital), and this equipment would allow us to measure these in children
with chronic lung diseases for the first time in Hull and East Yorkshire. It would enable us participate in clinical trials
if we wish to which bring in new treatments and change children’s lives for the better.

The main advantages of the device from the clinical stand point are as follows:

  1. These measurements are known to correlate with quality of life
  2. The measurements are sensitive to changes in treatment – so can be used to monitor response to therapy.
  3. It provides useful additional information to spirometry on mechanical properties of the respiratory system
    that may not be readily available with standard pulmonary function testing.
  4. Standard spirometry can mask the effectiveness of a bronchodilator while the tidal breathing manoeuvre of
    FOT can reveal the effectiveness of a bronchodilator
  5. It allows for degree of obstruction to be measured during the breath cycle, not possible in any other form of testing.

The testing is not reliant on any coordination or effort and  requires minimal subject cooperation which
is a significant advantage with young children or critically ill patients