Time-course of ventilation, arterial and pulmonary CO2 tension during CO2 increase in humans

Abstract

A change of ventilation (VE), PaCO 2 (arterial CO 2 tension) and PvCO 2 (pulmonary arterial CO 2 tension) with time was not evaluated precisely during exercise or CO 2 rebreathing in humans. In this study, changes of these variables with time were fitted to exponential curves {y = Exp (x/ T + A) + k} and compared. When exercise pulmonary hemodynamics was examined in 15 cardiac patients to decide therapies, we asked the patients to undergo CO 2 rebreathing using air with supplementation of consumed O 2 . Arterial and pulmonary blood was drawn every minute. During exercise, T was 28.2 ± 8.4 and 26.8 ± 12.4, and A was 0.80 ± 0.50 and 0.50 ± 0.90 in VE and PvCO 2, respectively, with no statistical differences. During CO 2 rebreathing, T was 18.6 ± 5.8, 41.8 ± 38.0 and 21.6 ± 9.7 and A was 0.39 ± 0.67, 1.64 ± 1.35 and 0.17 ± 0.83 in VE, PaCO 2 and PvCO 2, respectively, with statistical difference of PaCO 2 from other variables, suggesting that VE and PvCO 2 showed same mode of change according to time but PaCO 2 did not. © Springer Science+Business Media Dordrecht 2012.