Role of airway receptors in altitude-induced dyspnea

Purpose: The purpose of Us study was to examine the role of airway receptor s in respiratory-related sensations after ascent to altitude. Methods: Rati ngs of respiratory-related sensations, perceived exertion and acute mountai n sickness, heart rate, and peripheral oxygen saturation were recorded at r est and exercise in male and female subjects who had inhaled either aerosol ized saline or saline with tetracaine after acute ascent to an altitude of 3500 m and after prolonged acclimatization of 18 d at altitudes between 400 0 and 5000 m. Results: Tetracaine had no effect on respiratory-related sens ations at altitude either at rest or during exercise, and male and female s ubjects experienced similar respiratory-related sensations. Sensations of r apid breathing were experienced at rest after acute exposure to 3500 ra as compared with sea level, but not after acclimatization to 5000 m. Sensation s of rapid breathing, air hunger, and heavy breathing were experienced duri ng exercise after acute and prolonged altitude exposure as compared with se a level, with a sensation of chest tightness experienced at 3500 m and a se nsation of gasping experienced at 5000 m. Conclusion: These results suggest that airway afferents play no role in the respiratory-related sensations e xperienced by male and female subjects either during acute ascent to altitu de or after prolonged acclimatization at altitude.