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Nasal peak inspiratory flow at altitude
P W Barry1, N P Mason, J P Richalet
1Dept of Child Health, University of Leicester, UK.
The European Respiratory Journal
|February 15, 2002
Summary
Nasal peak inspiratory flow (NPIF) increases with altitude, but less than oral flow. This suggests nasal flow limitation, not caused by cold, dry air, may occur at high altitudes.
Area of Science:
- Environmental Physiology
- Respiratory Physiology
Background:
- Hypobaric hypoxia presents challenges to respiratory function.
- Nasal airflow dynamics at altitude are not fully understood.
- Previous hypotheses linked nasal blockage to cold, dry air at altitude.
Purpose of the Study:
- To investigate changes in nasal peak inspiratory flow (NPIF) under controlled hypobaric hypoxia.
- To compare NPIF changes with oral peak inspiratory flow (OPIF) and expiratory flow (OPEF).
- To test the hypothesis that nasal blockage at altitude is due to cold, dry air.
Main Methods:
- Eight subjects participated in Operation Everest III (COMEX '97), ascending to a simulated 8,848 m altitude.
- Nasal peak inspiratory flow (NPIF) and oral peak inspiratory and expiratory flow (OPIF, OPEF) were measured at 0 m, 5,000 m, and 8,000 m.
- Environmental conditions (temperature, humidity) were strictly controlled.
Main Results:
- NPIF increased by 16% from sea level to 8,000 m.
- OPIF increased significantly more (47%) than NPIF.
- The rise in NPIF with altitude was less than predicted by air density changes and significantly lower than OPIF/OPEF increases.
Conclusions:
- Nasal peak inspiratory flow increases with ascent to altitude.
- The observed rise in NPIF is less than that of oral flows and air density predictions, suggesting nasal flow limitation.
- Findings refute the cold, dry air hypothesis for nasal blockage at altitude, indicating a need for further research into nasal blockage's impact on activity.