1. in 10 patients with pulmonary fibrosis and in seven control subjects, we measured the pressure at the mouth 0.1 s after onset of an inspiration against occluded airway (P0.1), minute ventilation (VI), breathing frequency (fr), tidal volume (VT), inspiratory duration (Tl) and calculated the mean inspiratory flow (VT/Tl) and the fraction of the breath cycle devoted to inspiration (Tl/Ttot.). in the patients measurements were made at normal arterial oxygen saturations (Sao2), before and after lignocaine airway anaesthesia.
2. Efficacy of airway anaesthesia was tested by the cough response to citric acid inhalation.
3. in pulmonary fibrosis P0.1, f1 and VT/Tl were greater than in the control subjects, VT and Tl, were smaller and Tl/Ttot. and VI were not different.
4. Effective airway anaesthesia did not modify P0.1 and breathing pattern parameters observed in pulmonary fibrosis.
5. These results suggest that airway receptors do not contribute to a major extent to the control of breathing in pulmonary fibrosis.