Effects of five nights of normobaric hypoxia on the ventilatory responses to acute hypoxia and hypercapnia.
This study examined the effects of five nights of normobaric hypoxia on ventilatory responses to acute isocapnic hypoxia (AHVR) and hyperoxic hypercapnia (AHCVR). Twelve male subjects (26.6 +/- 4.1 years, standard deviation (S.D.)) slept 8-9 h per day overnight for 5 consecutive days at a simulated altitude of 4,300 m (FiO2= approximately 13.8%). Using the technique of dynamic end-tidal forcing, the AHVR and AHCVR were assessed twice prior to, immediately after, and 5 days following the hypoxic exposure. Immediately following the exposure, AHVR was increased by 1.6 +/- 1.3 L min(-1) %(-1) (P<0.01) when compared with control values. Likewise, after the exposure, ventilation in hyperoxia was increased (P<0.001) and was associated with both an increase in the slope (1.5 +/- 1.4 L min(-1) Torr(-1); P<0.05) and decrease in the intercept (-2.7 +/- 4.3 Torr; P<0.05) of the AHCVR. These results show that five nights of hypoxia can elicit similar perturbations, in both AHVR and AHCVR, as have been reported during more chronic altitude exposures.
Ainslie
Philip N
PN
Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Heritage Medical Research Building Room 209, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
Kolb
Jon C
JC
Ide
Kojiro
K
Poulin
Marc J
MJ
D000328:Adult; D000531:Altitude; D000704:Analysis of Variance; D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000378:metabolism; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology*; D013997:Time Factors; D014691:Ventilation / Q000379:methods
D002245:Carbon Dioxide; D010100:Oxygen