Alveolar PCO2 oscillations and ventilation at sea level and at high altitude
| Autor: | C. J. Collier, H. J. A. van Ruiten, Avijit Datta, C. B. Wolff, Erik R. Swenson, Annabel H. Nickol, James S. Milledge, David Collier |
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| Rok vydání: | 2007 |
| Předmět: |
medicine.medical_specialty
Periodicity Time Factors Meteorology Physiology Acclimatization Biology pCO2 Hypercapnia Physiology (medical) Internal medicine Respiration Administration Inhalation medicine Humans Respiratory cycle Respiratory system Hypoxia Exercise Sea level Altitude Effects of high altitude on humans Carbon Dioxide Chemoreceptor Cells Bicycling Mountaineering Acetazolamide Oxygen Pulmonary Alveoli Inhalation Acute Disease Chronic Disease Cardiology Breathing Ventilatory drive Pulmonary Ventilation |
| Zdroj: | Journal of applied physiology (Bethesda, Md. : 1985). 104(2) |
| ISSN: | 8750-7587 |
| Popis: | This study examines the potential for a ventilatory drive, independent of mean Pco2, but depending instead on changes in Pco2 that occur during the respiratory cycle. This responsiveness is referred to here as “dynamic ventilatory sensitivity.” The normal, spontaneous, respiratory oscillations in alveolar Pco2 have been modified with inspiratory pulses approximating alveolar Pco2 concentrations, both at sea level and at high altitude (5,000 m, 16,400 ft.). All tests were conducted with subjects exercising on a cycle ergometer at 60 W. The pulses last about half the inspiratory duration and are timed to arrive in the alveoli during early or late inspiration. Differences in ventilation, which then occur in the face of similar end-tidal Pco2 values, are taken to result from dynamic ventilatory sensitivity. Highly significant ventilatory responses (early pulse response greater than late) occurred in hypoxia and normoxia at sea level and after more than 4 days at 5,000 m. The response at high altitude was eliminated by normalizing Po2 and was reduced or eliminated with acetazolamide. No response was present soon after arrival (2 oscillations provide a feedback signal for respiratory control, independent of changes in mean Pco2, suggesting that natural Pco2 oscillations drive breathing in exercise. |
| Databáze: | OpenAIRE |
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