The Bronchial Response, but not the Pulmonary Response to Inhaled Methacholine Is Dependent on the Aerosol Deposition Pattern: Discussion
The responses also tended to be more protracted than after the central airway deposition of methacholine, and in contrast to the findings after central airway deposition, the decrement of sGaw relative to baseline remained statistically significant (p<0.05) 30 min after the challenge. The three patients who had subnormal sGaw at baseline tended to have a more long-standing bronchoconstriction than the others; sGaw remained at 41 ±11 percent of baseline 30 min after the challenge, while sGaw partially reversed within the same time in the remaining patients (76 ±13 percent of the baseline values). canadianfamilypharmacy
Similar to the response after the deposition of methacholine in trachea and main bronchi, log SDQ increased significantly relative to the baseline immediately after the challenge, peaked at the 30-min measurement, and remained abnormal in the rest of the experiment. Bimodal distributions of the perfusion were recorded in seven patients, and the abnormalities remained 2 h after the challenge in those patients. The maximal decrement in arterial P02 was reached immediately after the challenge, and returned to baseline within 120 min (Table 1), and there was no significant change in arterial PCO2. Thus, the abnormalities in data obtained from the inert gas elimination test and from the measurements of arterial P02 tended to have similar magnitude and time courses in the two separate experiments, with different airway deposition patterns of methacholine.
Transient bronchoconstriction was attained in the two separate experiments, and the constriction, as assessed by the maximal change in sGaw from baseline, was more pronounced after a central airway deposition of methacholine than after the peripheral airway deposition. Since changes in sGaw mainly reflect changes in larger- or medium-sized bronchial tone, the present study indicates dose-dependent responses to inhaled nebulized methacholine in the central airways in accordance with previously published reports.