Retention of ventilatory pattern learning in normal subjects.

Two procedures for training normal subjects to increase inspiratory duration (TI) were compared. In the first procedure (feedback), a visual signal informed subjects of their TI value just after the end of each inspiration; subjects were instructed to maintain TI for a set interval previously established by the experimenter. The second procedure (pacing) consisted of delivering a periodic signal to subjects and instructing them to adjust their respiratory frequency to this signal. All subjects participated in two identical sessions, 24 h apart. Comparison of performances between the two sessions provides evidence for a retention effect in feedback subjects only, suggesting the superiority of this method. Voluntary increase of TI during training induced a spontaneous increase of tidal volume, independent of any instruction. This increase in breathing amplitude cannot be explained in terms of chemical control of breathing.

[Analysis of the dependence of respiratory data during spontaneous ventilation at rest]. / Analyse de la dépendance des données respiratoires au cours de la ventilation spontanée de repos.

Inspiratory duration (TI), cycle duration (TTOT), and tidal volume (VT) were continuously measured in 11 normal subjects during 400 respiratory cycles. Small breath to breath changes in these variables were separately analyzed. For each of these variables, successive observations are not statistically independent; "large" values tend to be followed by "large" values. A respiratory feedback may be involved in this sequential dependence. In that case, any known system of respiratory control could be associated with it, even those with time constant or delay longer than one cycle duration.