Effects of changes in respiratory pattern on physiological dead space

E$ects of changes in resfiiratory pattern on physiological dead space. J. A ppl. Physiol. 3 l(3) : 478-483. 197 1.-The effects on pulmonary physi-ological dead space (VD) of changes in end-inspiratory lung vol-ume, tidal volume, and respiratory frequency were studied in normal young men, young women, and elderly men. In the young men at rest breathing at a normal tidal volume (mean 0.73 liter) and normal respiratory rate (mean 13 /min) VD increased 2.7 ml / 100 ml increase in end-inspiratory lung volume (EILV) at lung volumes greater than 50y0 total lung capacity. VD was greater in the older subjects than in the younger for any EILV. A 3- to 4-fold increase in respiratory rate alone or an increase in tidal volume to 1.67 liters (mean) caused a moderate increase in VD, but when both were increased together there was a marked increase in VD (often to more than 500 ml) for any EILV. The range of values for VD was very narrow for the young subjects breathing at