RESPONSE OF ASTHMATICS TO METHACHOLINE AND SUGGESTION

Abstract

Effects of diluent, methacholine and [psychological] suggestion on pulmonary function were studied in 9 asthmatic subjects. On day 1, flavored diluent was given as a control preparation. On day 2 increasing concentrations of similarly flavored methacholine were administered. On day 3 the effect of flavored diluent plus suggestion was studied. Although all vegetbles were affected, the dose-response relationships for methacholine were most pronounced for specific airway conductance and airway resistance, in contrast to maximal mid-expiratory flow, forced expiratory volume in 1 s and forced vital capacity. Suggestion toward bronchoconstriction significantly affected only the plethysmographic parameters, specific airway conductance and airway resistance, and not the spirometric variables. Both airway resistance and 1-s forced expiratory volume showed slight, but significant, changes as a result of bronchodilator suggestion, which was used to overcome the suggestion toward bronchoconstriction. Because suggestion had a greater effect on large airways than peripheral airways, a role for the vagus is implied. Any protocol using body plethysmography must consider a possible effect of suggestion on results.