Airway reactivity in subjects with viral upper respiratory tract infections: the effects of exercise and cold air.

To define airway hyperreactivity further in symptomatic upper respiratory tract infection (URI), we compared in the setting of viral URI the respiratory effects of inhaling histamine to that of exercising with room air (993 +/- 300 kpm/min; 22 degrees +/- 2 degrees C), cold air breathing (-8 +/- 2 degrees C), and exercising with cold air (993 +/- 300 kpm/min; -8 degrees +/- 2 degrees C). Thirteen previously healthy, nonsmoking, nonatopic adults with URI were evaluated at the time of presentation and 1, 3, and 6 wk thereafter. At the initial presentation there was a 28 +/- 14% decrease in mean airway conductance (SGaw) after inhalation of histamine (p > 0.001). By 6 wk, airway reactivity to histamine decreased in 9 of 13 subjects. After exercise with cold air, there was a 12.5 +/- 7.5% decrease in mean SGaw (p < 0.001). By 6 wk, exercise with cold air no longer produced a decrease in SGaw (p > 0.05). In 5 additional subjects this airway reactivity to exercise with cold air was blocked by previous administration of atropine and by oropharyngeal anesthesia. We conclude that during viral URI there occurs transient airway hyperreactivity ot the combination of exercise with cold, dry air and that the upper airway and parasympathetic nervous system have important roles in these responses.