title: [Influence of sequential breath-holding on the slope of phase III (author's transl)].
abstract: Many factors contribute to the slope of phase III of the single-breath nitrogen test (SB-N2). By its effect of nitrogen concentrations, alveolar oxygen exchange may be responsible for a fraction of this slope. In fact, the slope of phase III is steeper when expiratory time is prolonged. We studied the effect of two sequential breath-holding periods of 20 seconds each with ten healthy young male volunteers, by SB-N2 and a reverse technique (SB-R). We observed a sudden increase (mean 1.27%) in the expired nitrogen concentration after each breath-holding period. Closing volume remained the same in all tests, but the slope of phase IV decreased by 44% in SB-N2A (SB-N2 with breath-holding) and increased by 55% in SB-RA. Expiratory vital capacity was significantly less after breath-holding. These data suggest that gas exchange during expiration is partly responsible for the slope of phase III.
mesh_terms: D000328:Adult; D003011:Closing Volume; D006801:Humans; D008297:Male; D009584:Nitrogen; D010100:Oxygen / Q000502:physiology; D011650:Pulmonary Alveoli / Q000503:physiopathology*; D012119:Respiration; D014797:Vital Capacity
chemical_list: D009584:Nitrogen; D010100:Oxygen
vernacular_title: L'influence d'apnées séquentielles sur le plateau alvéolaire.