Comparison of ventilatory response between dead space and CO2 breathing in humans.

Abstract

Ventilatory response during external dead space (tube) breathing and C02 inhalation for given increase in PETco2 were compared at different levels of PETo2 (hyperoxia, normoxia, and hypoxia) in human subjects. At all the PETo2 levels studied, magnitude of increment in minute ventilation (VE) and tidal volume were larger in the dead space breathing than in the C02 inhalation. The slope of C02-ventilation response line was significantly steeper in the dead space breathing only in the hypoxic condition. There was no significant difference in frequency response to C02 between the two methods. These results suggested that augmented ventilatory response to C02 in the dead space breathing occurs in the condition of peripheral chemoreceptor activation.

Circulatory and Respiratory Response to Exercise With Added Respiratory Dead Space

“…6). It follows that VT increases by 1.5 times from 0 cm 3 to 1600 cm 3 . the changes in the rf/Vt ratio are presented in table 6.…”

“…The volume of dead space was increased from 200 cm 3 (in exercise test no. 2) to 1600 cm 3 (in exercise test no.…”

“…The distribution of significant differences is shown in Table 2. VT tends to increase proportionally to the volume of added dead space, from 1.62 ± 0.29 (at 0 cm 3 ) to 2.43 ± 0.24 l (at 1600 cm 3 ). Vt/Vt 0cm 3 at 1600 cm 3 equals 1.5 (Tab.…”

“…Most studies have focused on three aspects: increase in pulmonary ventilation (O'Donnell et al [1], takahashi et al [2]), respiratory airway resistance (Maruyama et al [3], Poon [4,5]) and arterial carbon dioxide pressure (Koppers et al [6], toklu et al [7]). these reactions are caused by the application of added dead space by means of a tube.…”

“…It has been proved that at the same values of end-tidal carbon dioxide partial pressure (PetcO 2 ) breathing through the tube always causes * corresponding author. a greater increase in ventilation than inhaling hypercapnic gas without a tube (Maruyama et al [3], Poon [4,5]). …”