{'fraction_non_alphanumeric': 0.034266133637921185, 'fraction_numerical': 0.018846373500856654, 'mean_word_length': 5.0, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
P0.1 during exercise in normal subjects breathing mixtures of gas with varying densities.

BACKGROUND AND AIM
The aim of the study was to re-examine the occlusion pressure measured simultaneously in the mouth (P0.1) and the oesophagus (Poes.1) during exercise in normal subjects submitted to different gas mixtures.


METHODS
7 healthy men breathing random gas mixtures containing 21% oxygen with either by 79% helium (He-O2) or sulphur hexafluoride (SF6-O2) and room-air, were studied during a steady-state 90w exercise performed on a cyclo-ergometer. Ventilatory parameters were derived from the flow signal recorded by a pneumotachograph calibrated with the different gas mixtures. Three pressure transducers (mouth, eosophageal and gastric) were checked to have iso-time identical responses up to 4Hz. P0.1, Poes.1, deltaPoes (difference in oesophageal pressure between end-inspiratory and end-expiratory levels) and deltaPdi (variation of transdiaphragmatic pressure between end-inspiratory and end-expiratory levels) were measured.


RESULTS
Hyperventilation associated with a similar deltaPoes/deltaPdi but a lower P0.1/deltaPdi ratio was observed in He-O2 breathing compared to SF6-O2 and air. Variable time delays between oesophageal and mouth pressures were observed during air and SF6-O2. Whatever the condition involved, no change was detected in the shape of the inspiratory pressure during the occlusion manoeuvres.


CONCLUSIONS
He-O2 breathing probably induced a change in the shape of the pressure wave later on in the inspiratory phase, making P0.1 not representing the total inspiratory drive. On the contrary in air and SF6-O2 conditions, P0.1 seemed to remain a useful tool for looking at the output of the respiratory controller.