Cardio-respiratory responses to hypoxia combined with CO2inhalation during maximal exercise.
We measured the effects of adding CO2to an inhaled hypoxic gas mixture on cardio-respiratory parameters during maximal exercise. Eight young males performed four incremental maximal exercise tests on cycle under ambient air, hypoxia (FIO20.125), inhaled CO2(FICO20.045), and combination of hypoxia and inhaled CO2. The highest ventilation (VE) and VE/CO2output were recorded in CO2inhalation and combined treatments. Arterial O2partial pressure was higher in combined than in hypoxia treatment, but the difference between the treatments narrowed from rest to end-exercise, at least partly because the magnitude of the increase in VE (%) at exercise was smaller in combined treatment than in hypoxia. Arterial O2content was higher in combined treatment than in hypoxia at rest, but no more at maximal exercise. Cardiac output was higher and O2extraction lower when breathing O2-poor gas mixtures than under the two other treatments. For a given oxygen consumption, hypoxia and combined treatment showed similar cardiac output and O2extraction.
Service de Physiologie et d'Explorations Fonctionnelles, Pôle de Pathologie Thoracique, Hôpitaux Universitaires de Strasbourg, France; Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France.
Stéphane
S
Doutreleau
Service de Physiologie et d'Explorations Fonctionnelles, Pôle de Pathologie Thoracique, Hôpitaux Universitaires de Strasbourg, France; Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France.
Irina
I
Enache
Service de Physiologie et d'Explorations Fonctionnelles, Pôle de Pathologie Thoracique, Hôpitaux Universitaires de Strasbourg, France; Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France.
Cristina
C
Pistea
Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France.
Fabrice
F
Favret
Service de Physiologie et d'Explorations Fonctionnelles, Pôle de Pathologie Thoracique, Hôpitaux Universitaires de Strasbourg, France; Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France.
Evelyne
E
Lonsdorfer
Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France.
Stéphane
S
Dufour
Service de Physiologie et d'Explorations Fonctionnelles, Pôle de Pathologie Thoracique, Hôpitaux Universitaires de Strasbourg, France; Equipe d'Accueil 3072, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, France. Electronic address: Anne.Charloux@chru-strasbourg.fr.
Anne
A
Charloux
D001642:Bicycling / Q000502:physiology; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism*; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D012119:Respiration; D013147:Spirometry; D055815:Young Adult
D002245:Carbon Dioxide; D010100:Oxygen
Blood gases; CO(2) inhalation; Hypoxia; Maximal exercise; Ventilation