Respiratory modulation in response to high-frequency airway occlusion delivered during inspiration or expiration

To investigate whether 30 breaths performed against a high-frequency airway occlusion stimulus modulates ventilatory control both within-phase (within the phase of breathing that the stimulus was presented) and opposite-phase (in the opposite-phase of breathing to that in which the stimulus was presented) of the respiratory cycle. Ten healthy subjects (3 female, 7 male; 22-44 years old) completed 30 breaths prior to and following 30 inspirations or expirations against a high-frequency occlusion stimulus (youbreathe, Exoscience Ltd., London, UK), pressure-matched resistive loading or resting tidal breathing (no load) presented in a random order. The major findings from this study were that inspiratory-only high-frequency occlusion caused a significant augmentation in peak inspiratory airflow and shortening of expiratory time not observed during corresponding resistance. There were no residual effects of any intervention upon any measured ventilatory variables. High-frequency airway occlusion modulates ventilation both within-phase and in the opposite-phase, effects which are absent following resistive loaded breathing.