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Asthma in medium altitude – exercise‐induced bronchoconstriction in hypobaric environment in subjects with asthma
Author(s) -
Berntsen S.,
Stensrud T.,
Ingjer F.,
Vilberg A.,
Carlsen K.H.
Publication year - 2005
Publication title -
allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.363
H-Index - 173
eISSN - 1398-9995
pISSN - 0105-4538
DOI - 10.1111/j.1398-9995.2005.00914.x
Subject(s) - bronchoconstriction , medicine , asthma , salbutamol , inhalation , respiratory minute volume , hypobaric chamber , heart rate , anesthesia , tidal volume , respiratory rate , ventilation (architecture) , effects of high altitude on humans , pulmonary function testing , cardiology , respiratory system , blood pressure , mechanical engineering , engineering , anatomy
Background: Hypoxic gas inhalation has been reported to enhance airway responsiveness and results in bronchoconstriction in animal models and in humans with asthma. However, the data have so far been conflicting. The aim of the present study was to examine the effect of reduced barometric pressure on exercise‐induced bronchoconstriction (EIB) in subjects with asthma. Methods: Twenty subjects (10–45 years old, ♂/♀ = 13/7) with asthma (at least 10% reduction in forced expiratory volume in 1‐second postexercise) participated in exercise testing in barometric pressure corresponding to altitudes of 200 (normobaric) and 2500 (hypobaric) m above sea level in random order on separate days. Lung function was measured before and after exercise, as well as after inhalation of salbutamol. Heart rate, oxygen uptake (), arterial oxygen saturation (S p O 2 ), respiratory gas exchange ratio (RER) and minute ventilation () were measured during exercise. Results: There was no difference in lung function after exercise. The and HR peak during exercise did not differ. The RER peak was higher ( P = 0.04) in hypobaric environment. The decreased 10.1% (7.2–13.0) [mean (95% confidence intervals)] ( P < 0.001) from normobaric to hypobaric environment. At the same time, S p O 2 at decreased from 94.4 (92.2–96.6) to 85.6% (82.8–88.4) ( P < 0.001). Conclusions: A barometric pressure corresponding to altitude of 2500 m did not increase EIB in subjects with asthma. The reduction in is most probably due to the lower S p O 2 in hypobaric environment.