Attenuation of induced bronchoconstriction in healthy subjects: effects of breathing depth.

Autor: Salerno, Francesco G., Pellegrino, Riccardo, Trocchio, Gianluca, Spanevello, Antonio, Brusasco, Vito, Crimi, Emanuele
Předmět:
Zdroj: Journal of Applied Physiology; Mar2005, Vol. 98 Issue 3, p817-821, 5p
Abstrakt: The effects of breathing depth in attenuating induced bronchoconstriction were studied in 12 healthy subjects. On four separate, randomized occasions, the depth of a series of five breaths taken soon (∼1 min) after methacholine (MCh) inhalation was varied from spontaneous tidal volume to lung volumes terminating at ∼80, ∼90, and 100% of total lung capacity (TLC). Partial forced expiratory flow at 40% of control forced vital capacity (Vpart) and residual volume (RV) were measured at control and again at 2, 7, and 11 min after MCh. The decrease in &Vdot;part and the increase in RV were significantly less when the depth of the five-breath series was progressively increased (P < 0.001), with a linear relationship. The attenuating effects of deep breaths of any amplitude were significantly greater on RV than &Vdot;part (P < 0.01) and lasted as long as 11 min, despite a slight decrease with time when the end-inspiratory lung volume was 100% of TLC. In conclusion, in healthy subjects exposed to MCh, a series of breaths of different depth up to TLC caused a progressive and sustained attenuation of bronchoconstriction. The effects of the depth of the five-breath series were more evident on the RV than on &Vdot;part, likely due to the different mechanisms that regulate airway closure and expiratory flow limitation. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index