RESPIRATORY HEAT AND WATER-LOSS DURING EXERCISE IN PATIENTS WITH ASTHMA - EFFECT OF REPEATED EXERCISE CHALLENGE

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 63  (5) , 472-480
Abstract
The loss of heat and water from the airways during repeated exercise challenge was investigated. Asthmatic patients (26) performed 6-8 min exercise on a bicycle ergometer at a workload equivalent to 57-85% of their predicted maximum working capacity. Sixteen patients performed 2 exercise tests separated by 40-52 min. Exercise-induced asthma (EIA) occurred in all patients after initial challenge, but 8 had significant protection from EIA following a 2nd challenge. This protection was not associated with a reduction in heat and water loss from the airways during exercise. Another 10 patients performed 2 exercise tests 2-3 h apart. The 2nd test was preceded by the administration of 200 .mu.g salbutamol areosol. There was no significant difference between the 2 tests in loss of heat and water from the airways during exercise. EIA occurred in all patients after the initial challenge but was inhibited by the salbutamol after the 2nd challenge. The reduction in EIA as a result of a refractory period or in response to aerosol salbutamol is not due to changes in heat and water loss from the airways during exercise.