Pulmonary edema is associated with peribronchial cuffing, so that the outer diameter of the airways increases. This implies a shorter distance to be covered by alveolar attachments, and hence a decrease in the distending pressure to which intrapulmonary airways are subjected. Furthermore, intrabronchial edema and vascular engorgement will diminish the internal airway diameter. The smaller distending pressure is associated with a diminished afterload against which smooth muscles contract; the submucosal swelling is associated with a percentage-wise greater increase in airways resistance for the same muscle shortening compared to a normal initial calibre. Maximal airway narrowing will be enhanced on both accounts.