Daily pattern of breathing in healthy young men.

Daily changes in the pulmonary function indices were examined in 30 healthy young men. The breathing pattern technique (Lungtest system, MES, Cracow) was used to measure daily changes in basic ventilatory parameters every 3 hours during a 24-hour period. The results revealed significant daily variables in VT (tidal volume), MV (minute ventilation), VT/TI (mean inspiratory flow), and the ratios of MV/P0. 1, (minute ventilation/mouth occlusion pressure) and P0.1/VT/TI. There was lack of significant variations in the other variables. The daily minima in the variables occurred during the usual sleep period at 2:00, 5:00 and also at 8:00 hours. The results of this study demonstrate that healthy adults have small, but significant, daily variations in some of the breathing parameters, although, overall, the breathing pattern remains relatively stable around the clock.