Clinical Dysautonomia in Patients with Bronchial Asthma: Study with Seven Autonomic Function Tests

Abstract

Fifty asthmatic patients and 20 healthy control subjects, carefully age- and sex-matched, were subjected to seven standardized tests to evaluate their autonomic status. Due care was taken to remove factors which could interfere with results. Of the tests concerned with the parasympathetic system, the intravenous atropine test (p>0.10) and heart rate response to standing (p>0.01) which measured the basal parasympathetic tone, did not show a significant difference. Tests requiring stimulation of the parasympathetic system, ie, deep breathing test (p<0.001), Valsalva maneuver (p<0.001), and carotid sinus massage (p<0.001) showed significantly heightened response. Postural fall of blood pressure (p>0.10) and sustained hand grip test (p>0.10), chiefly concerned with the sympathetic system, did not show a significant difference. Of the 50 asthmatic patients, nine were atopic and 41 nonatopic. When the results were compared in the two groups separately, we found that there was no alteration in the measurements except the intravenous atropine test which showed heightened response with atopic subjects (p<0.05). These results suggest that hyperresponsiveness of the parasympathetic system is an important factor in producing bronchial spasm in asthmatic patients, and atopic and nonatopic subjects do not differ much in their autonomic status. Fifty asthmatic patients and 20 healthy control subjects, carefully age- and sex-matched, were subjected to seven standardized tests to evaluate their autonomic status. Due care was taken to remove factors which could interfere with results. Of the tests concerned with the parasympathetic system, the intravenous atropine test (p>0.10) and heart rate response to standing (p>0.01) which measured the basal parasympathetic tone, did not show a significant difference. Tests requiring stimulation of the parasympathetic system, ie, deep breathing test (p<0.001), Valsalva maneuver (p<0.001), and carotid sinus massage (p<0.001) showed significantly heightened response. Postural fall of blood pressure (p>0.10) and sustained hand grip test (p>0.10), chiefly concerned with the sympathetic system, did not show a significant difference. Of the 50 asthmatic patients, nine were atopic and 41 nonatopic. When the results were compared in the two groups separately, we found that there was no alteration in the measurements except the intravenous atropine test which showed heightened response with atopic subjects (p<0.05). These results suggest that hyperresponsiveness of the parasympathetic system is an important factor in producing bronchial spasm in asthmatic patients, and atopic and nonatopic subjects do not differ much in their autonomic status.