Acute bronchodilating effect of transcutaneous nerve stimulation in asthma. A peripheral reflex or psychogenic...

The acute effect of electric transcutaneous nerve stimulation (TNS) on bronchomotor tone was studied in 20 asthmatics. The stimulation was applied to four classical acupuncture points on the chest and back, and bronchomotor response was determined by measuring peak expiratory flow (PEF). The experiments consisted of an adaptation period, placebo "stimulation", TNS, and an isoprenaline inhalation test, in that order. In 11 patients PEF increased significantly (greater than 15%) after placebo "stimulation"; the mean change in all 20 patients after that period was + 12% (P less than 0.01). TNS, however, did not change PEF significantly in any patient in spite of the fact that marked residual bronchoconstriction was shown in all patients demonstrated by an increase in PEF after inhalation of two isoprenaline puffs at the end of the experiment. The results suggest that the acute bronchodilatation obtainable with TNS is probably psychogenic; no cutaneous-bronchial reflex could be demonstrated. The same kind of psychogenic reaction may also be involved in the bronchodilator response to needle acupuncture in asthma.