Non-specific airway responsiveness to hyperventilation of low doses of sulfur dioxide and cold air of non-smoking healthy volunteers of different ages.

We examined the effect of hyperventilation (HV) of sulfur dioxide (SO2)-air and cold air for 5 minutes on airway responsiveness of 37 (12 females and 25 males) healthy non-smoking volunteers of different ages. Body-plethysmographic measurements of airway resistance (Raw) and intrathoracic gas volume (ITGV) were performed before, 3, 10 and 20 mins. after the end of HV of SO2-air or cold air. Specific airway resistance (sRaw), product of Raw x ITGV, was used to evaluate the airway responsiveness. The mean (standard error) of percent changes of sRaw (delta %sRaw) were 121 (22), 45 (8) and 25 (4) at 3, 10 and 20 mins. after the end of HV of SO2-air. The corresponding values were 52 (8), 25 (5) and 19 (3) after HV of cold air. The differences in delta %sRaw between HV of SO2 and cold air were statistically significant (two sided t-test) for the 3 (p < 0.01) and 10 (p < 0.05) mins. values. Hyperventilation of SO2 and cold air produced delta sRaw above 100% in 14 (37.8%) and 5 (13.5%) volunteers, respectively. The difference in frequencies of delta sRaw above 100% between the HV of SO2 and cold air was statistically significant (p < 0.05, chi 2-Test). We observed a decreasing order of airway responsiveness with increasing age following HV of SO2 but not after cold air. We conclude that airway responsiveness to SO2 is poorly related to the response to cold air.