Effect of hypobaria on ventilatory and CO2 responses to short-term hypoxic exposure in cats.
The effect of hypobaria on the ventilatory response to short-term hypoxia was studied by comparing the respiratory mechanical and inspired CO2 ventilatory responses to hypobaric hypoxia (438 mmHg) with normobaric hypoxia (11.8% FIO2). Fifteen spontaneously breathing, anesthetized cats were divided into three groups of five: time control, normobaric hypoxia and hypobaric hypoxia. Measurements of ventilation, gas exchange, and responses to intermittent CO2 rebreathing were collected over a 4 h period. PaO2 fell to 44.5 +/- 2.7 mmHg, PaCO2 fell to 24.8 +/- 0.9, and pH rose to 7.49 +/- 0.01 in both hypoxic groups. Tidal volume did not change with respect to time or condition, but frequency and ventilation were significantly increased in the hypobaric hypoxic group. The slope of the CO2 response was unchanged over time or by condition. These results suggest that hypobaric hypoxia may alter the pattern of breathing responses to hypoxia but not the CO2-response. If metabolic rate remained constant, these results could be explained by a difference in dead space between hypoxic conditions.
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- Pulmonary Ventilation
- Physiology
- Partial Pressure
- Oxygen
- Male
- Hypoxia
- Female
- Chemoreceptor Cells
- Cats
- Carbon Dioxide
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Pulmonary Ventilation
- Physiology
- Partial Pressure
- Oxygen
- Male
- Hypoxia
- Female
- Chemoreceptor Cells
- Cats
- Carbon Dioxide