Parenteral vs. inhaled atropine: density dependence of maximal expiratory flow

Publisher Website
Google Scholar
Abstract
Using forced vital capacity maneuvers, maximal expiratory flow rates (.ovrhdot.Vmax) and static elastic recoil pressures of the lung [Pst(L)] using quasi-static maneuvers in normal nonsmoking human subjects who were breathing air and after a wash-in of 80% He-20% O2 before and after both inhaled and i.v. administered atropine sulfate. By both routes there were equivalent increases in .ovrhdot.Vmaxair but different effects on density dependence (DD) of .ovrhdot.Vmax (DD = ratio of .ovrhdot.VmaxHeO2/.ovrhdot.Vmaxair) and on Pst(L). At 30% of vital capacity, DD decreased from an average of 1.47 to 1.32 (P < 0.01, paired t test) after inhaled drug and did not change after parenteral administration [1.44 vs. 1.48 (P > 0.2)]. After inhalation Pst(L) did not change, but after parenteral administration Pst(L) significantly decreased. There is a predominantly large-airway effect with the inhalation route and a more uniform dilatation after the parenteral dose. These results contrast with .beta.-adrenergic dilatation following which small-airway effects predominate regardless of route of administration.