We welcome the opportunity to respond to Drs Pellegrino and Brusasco.1 We are concerned primarily with their statement that “the acute response to bronchodilators is relatively easy to interpret when changes in FEV1 or FVC exceed the thresholds of their natural intraday variability (ie, 12% of baseline and 200 mL), thus, unequivocally indicating bronchodilation.”1
To test this statement with real data,2 we identified the most severe 44 of 316 patients with their initial highest FEV1 < 1.00 L (Table 1). We sorted them into three categories depending on their response to nebulized albuterol. Importantly, both the preaerolized and postaerosolized albuterol variability of these patients’ FEV1 values were low (the postdrug variabilities are not presented). Considering the highest and lowest predrug FEV1 values of each patient with an FEV1 < 1.00 L, the range of predrug highest and lowest individual values was between 10 and 200 mL with a mean ± SD of 56 ± 40 mL. All these results were from a retrospective analysis of patients routinely studied in a clinical laboratory; thus, we believe that this population is highly relevant to the topic.