Cold air and exercise challenge -- influence of minute ventilation

Exercises testing and cold air challenges are frequently used to assess airway hyperresponsiveness (AHR), but different goals are set for the two tests. We, therefore, wished to determine whether cold air and exercise challenge testing yielded similar responses and if any differences were due to differences in the maximum minute ventilation achieved. Twenty asthmatic subjects each performed a cold air (CACh) and an exercise (EXCh) challenge. Baseline forced expiratory volume in one second (FEV(1)) was recorded immediately pre-challenge and then serially for at least 10 minutes post-challenge. The maximum minute ventilation achieved was recorded. In the subjects who had at least a decrease in FEV(1) of 15% in response to the first CACh, a second CACh was performed, but at the maximum minute ventilation achieved during EXCh. Eleven subjects after CACh and four after EXCh had a greater than 15% decrease in FEV(1) (p = 0.05). The median decrease in FEV(1) was greater following the CACh (16.7%[25th to 75th percentile 10.4 to 19.9]) than the EXCh (6.9%[25th to 75th percentile 4.3 to 14.6]); (p = 0.0004). The median maximum minute ventilation achieved was greater with the CACh (89[66-141] L/min) than with the EXCh (61(40 to 102)L/min); (p < 0.0001). Only one of seven subjects who had previously responded to the CACh had a 15% decrease in FEV(1) when the CACh was repeated at the same maximum minute ventilation achieved during EXCh (p = 0.007). In conclusion, cold air and exercise challenges do not produce the same response. Our results highlight than an explanation is the differences in the maximum-minimum ventilation achieved.