Adaptive excitation signals for low frequency FOT

The low frequency Forced Oscillation Technique (FOT) has a high diagnostic potential for the detection of respiratory diseases. However, it is not yet widely accepted in clinical practice. The presence of the patient's breathing generally results in patient-unfriendly measurement protocols. These are needed to extract the important low frequency information about the patients' respiratory system.This work presents a novel technique to apply the low frequency FOT during spontaneous breathing. This is accomplished by adding an external visual stimulus to encourage the patient to approximately synchronize his/her breathing in combination with an excitation signal that is adapted to the patient's natural breathing frequency. The breathing and FOT contributions can therefore be separated. This paper contains a proof of concept of this method and proposes measurements on healthy subjects.