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Sea-level PCO2 relates to ventilatory acclimatization at 4,300 m
J T Reeves1, R E McCullough, L G Moore
1Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver 80262.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 1, 1993
Summary
Individual differences in how well people adapt to high altitude are linked to their breathing patterns at sea level. Specifically, resting ventilation and the hypoxic ventilatory response (HVR) predict acclimatization success and oxygen levels at altitude.
Area of Science:
- Physiology
- Altitude Medicine
- Respiratory Physiology
Background:
- Individual variability exists in acclimatization to altitude.
- Factors influencing this variation are not fully understood.
- Pre-ascent ventilation and hypoxic ventilatory response (HVR) are potential factors.
Purpose of the Study:
- To investigate if sea-level end-tidal PCO2 and HVR predict ventilatory acclimatization to altitude.
- To determine if these factors relate to oxygenation levels at high altitude.
Main Methods:
- 37 healthy males measured sea-level end-tidal PCO2.
- Subjects ascended to 4,300 m (Pikes Peak).
- Measurements of end-tidal PCO2 and arterial oxygen saturation (SaO2) were taken at altitude; 26 subjects had sea-level HVR measured.
Main Results:
- Sea-level end-tidal PCO2 varied widely (34-48 Torr).
- Higher sea-level end-tidal PCO2 correlated with lower SaO2 at altitude.
- Lower sea-level HVR correlated with higher end-tidal PCO2 at altitude, indicating poorer acclimatization.
Conclusions:
- Sea-level end-tidal PCO2 and HVR are significant predictors of ventilatory acclimatization to altitude.
- These baseline respiratory measures influence acclimatization extent and oxygenation levels.
- The magnitude of the hypoxic drive to breathe may affect ventilation across all altitudes.