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Autonomic regulation in asthmatics with gastroesophageal reflux
U Lodi1, S M Harding, H C Coghlan
1Division of Developmental and Clinical Immunology, University of Alabama at Birmingham, USA.
Study Objective:
To study the role of autonomic regulation in asthmatics with gastroesophageal reflux (GER).
Design:
Prospective study.
Setting:
Autonomic function laboratory of a 908-bed university hospital.
Participants:
Fifteen nonsmoking asthmatics with GER (six men, nine women; average age, 36 years).
Interventions:
Subjects were connected to an ECG monitor. BP was measured by sphygmomanometer at set intervals. After a resting period, each subject had heart rate and BP monitored during an 80 degrees passive tilt, Valsalva maneuver, quiet and deep breathing, handgrip, and an echo stress test of cortical arousal. Each autonomic function test was analyzed and defined as normal, hypervagal, hyperadrenergic, or mixed (a combination of hypervagal and hyperadrenergic responses) as compared with 23 age-matched normal control subjects from our laboratory (14 men, 9 women; average age, 35 years) and published normal control values. Each subject had an overall response score that was determined by the results of the tilt, Valsalva maneuver, and deep breathing maneuvers.
Results:
All asthmatics with reflux had at least one autonomic function test display a hypervagal response. Overall response scores show that eight of 15 asthmatics with GER had an overall hypervagal response, and seven had a mixed response. Of the seven asthmatics with GER who had a mixed response score, two had a hypervagal predominant response.
Conclusions:
Asthmatics with GER have evidence of autonomic dysfunction. Heightened vagal tone may be partially responsible for the heightened airway responsiveness to esophageal acidification in asthmatics with reflux.