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Original article
Effects of high altitude and cold air exposure on airway inflammation in patients with asthma
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  1. Sven F Seys1,2,
  2. Marc Daenen3,
  3. Ellen Dilissen1,
  4. Ruud Van Thienen4,
  5. Dominique M A Bullens5,
  6. Peter Hespel4,
  7. Lieven J Dupont2,6
  1. 1Department of Immunology and Microbiology, Laboratory of Clinical Immunology, KU Leuven, Leuven, Belgium
  2. 2Department of Clinical and Experimental Medicine, Laboratory of Pneumology, KU Leuven, Leuven, Belgium
  3. 3Department of Respiratory Medicine, Hospital of Oost-Limburg, Leuven, Belgium
  4. 4Department of Kinesiology, Exercise Physiology Research Group, KU Leuven, Leuven, Belgium
  5. 5Department of Immunology and Microbiology, Laboratory of Pediatric Immunology, KU Leuven, Leuven, Belgium
  6. 6Department of Respiratory Diseases, University Hospitals Leuven, KU Leuven, Leuven, Belgium
  1. Correspondence to Professor Lieven Dupont, Department of Respiratory Medicine, University Hospitals Leuven, KU Leuven, 49 Herestraat, Leuven B-3000, Belgium; lieven.dupont{at}uzleuven.be

Abstract

Aims Eighteen patients with asthma were evaluated during preparation to climb to extreme altitude in order to study the effects of low fractional inspired oxygen (FiO2), prolonged exposure to cold air and high altitude on lung function, asthma control and airway inflammation.

Methods Spirometry and airway inflammation (fractional exhaled nitric oxide (FeNO) and induced sputum) were studied under different test conditions: hypoxic (FiO2=11%) exercise test, 24-hour cold exposure (−5°C) and before, during and after an expedition that involved climbing the Aconcagua mountain (6965 m).

Results Forced expiratory volume in 1 s (FEV1) and FeNO values were slightly lower (p<0.04) after 1 h of normobaric hypoxia. FEV1 decreased (p=0.009) after 24-hour cold exposure, accompanied by increased sputum neutrophilia (p<0.01). During the expedition FEV1 and forced vital capacity decreased (maximum FEV1 decrease of 12.3% at 4300 m) and asthma symptoms slightly increased. After the expedition the Asthma Control Test score and prebronchodilator FEV1 were reduced (p<0.02), sputum neutrophil count was increased (p=0.04) and sputum myeloperoxidase levels, sputum interleukin 17 mRNA, serum and sputum vascular endothelial growth factor A levels were significantly higher compared with baseline. Patients with asthma with the lowest oxygen saturation during the hypoxic exercise test were more prone to develop acute mountain sickness.

Conclusions Exposure to environmental conditions at high altitude (hypoxia, exercise, cold) was associated with a moderate loss of asthma control, increased airway obstruction and neutrophilic airway inflammation. The cold temperature is probably the most important contributing factor as 24-hour cold exposure by itself induced similar effects.

  • Asthma
  • Cytokine Biology
  • Exercise
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