A study of autonomic status and its effect on ventilatory functions in bronchial asthma.

The present study was undertaken to evaluate the autonomic nervous function in patients with bronchial asthma after indirect autonomic stimulation by seven different manoeuvres. A total of 30 cases of bronchial asthma and 20 healthy matched controls were studied after excluding all other diseases and drugs which could have a modulating effect on autonomic function. The tests used were: heart rate responses to the Valsalva manoeuvre, deep breathing, intravenous atropine, carotid sinus massage and standing from the supine position, and, the blood pressure responses to sustained handgrip and to standing from the supine position, the former five being tests of parasympathetic function and the latter two of sympathetic function. A significant difference in responses was observed in asthmatics who showed heightened cardiovascular responses to tests of parasympathetic function as compared to controls. Ventilatory function parameters (FVC and PEFR) also showed a parallel enhanced response (marked decrease) to parasympathetic stimulation by Valsalva manoeuvre, deep breathing and carotid sinus massage in asthmatics compared to controls. This aspect of differences in ventilatory response has not been previously reported in literature. No significant differences were found in the blood pressure responses to sustained handgrip and to standing from the supine position. Correlations between the autonomic status of the asthmatics with the clinical characteristics of the patients were analysed.