Cough frequency and cough-receptor sensitivity are increased in man at altitude

Clin Sci (Lond). 1997 Aug;93(2):181-6. doi: 10.1042/cs0930181.

Abstract

1. Travellers to high altitude often complain of paroxysmal cough, which has not been previously investigated. We recorded overnight cough frequency and cough-receptor sensitivity to inhaled citric acid in a group of climbers travelling to 5300 m or higher. 2. Cough frequency, monitored in ten subjects, increased from a median of 0 coughs at sea level (range 0-1) to 5 coughs at 5000 m (range 0-13) and to over 60 coughs in subjects ascending to 7000 m. Citric acid cough threshold, measured in 42 subjects, was unchanged on arrival at 5300 m compared with sea level (geometric mean difference 1.26, 95% confidence intervals 0.84-1.89, P = 0.25), but was significantly reduced after 6 days, or more, at altitude compared with sea level (geometric mean difference 2.2, 95% confidence intervals 1.54-3.15, P = 0.0002). Cough threshold was not related to symptoms of acute mountain sickness, oxygen saturation, carbon dioxide tension or lung function. 3. These results indicate an increase in cough and cough-receptor sensitivity after some days at altitude. This may be due to respiratory tract damage from breathing cold dry air at increased ventilatory rates. Other explanations, such as sub-clinical pulmonary oedema or an effect on the cough centre of acclimatization to altitude, cannot be excluded.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Altitude*
  • Bronchial Provocation Tests
  • Citric Acid
  • Cough / chemically induced
  • Cough / etiology*
  • Humans
  • Nebulizers and Vaporizers
  • Sensory Receptor Cells / physiopathology
  • Sensory Thresholds / physiology

Substances

  • Citric Acid