The following is the abstract of the article discussed in the subsequent letter:

Verbanck, S., D. Schuermans, A. Van Muylem, M. Paiva, M. Noppen, and W. Vincken. Ventilation distribution during histamine provocation. J. Appl. Physiol. 83(6):1907-1916, 1997.We investigated ventilation inhomogeneity during provocation with inhaled histamine in 20 asymptomatic nonsmoking subjects. We used N₂ multiple-breath washout (MBW) to derive parameters S_cond and S_acin as a measurement of ventilation inhomogeneity in conductive and acinar zones of the lungs, respectively. A 20% decrease of forced expiratory volume in 1 s (FEV₁) was used to distinguish responders from nonresponders. In the responder group, average FEV₁ decreased by 26%, whereas S_cond increased by 390% with no significant change in S_acin. In the nonresponder group, FEV₁ decreased by 11%, whereas S_cond increased by 198% with no significant S_acin change. Despite the absence of change in S_acin during provocation, baseline S_acin was significantly larger in the responder vs. the nonresponder group. The main findings of our study are that during provocation large ventilation inhomogeneities occur, that the small airways affected by the provocation process are situated proximal to the acinar zone where the diffusion front stands, and that, in addition to overall decrease in airway caliber, there is inhomogeneous narrowing of parallel airways.