Study objectives: To evaluate patients for vocal cord dysfunction (VCD) in a military population presenting with symptoms of exertional dyspnea.
Design: Cross-sectional, controlled study.
Setting: Pulmonary disease clinic at an army tertiary care center.
Patients: Forty military patients with complaints of exertional dyspnea and 12 military asymptomatic control subjects.
Intervention: Patients underwent direct visualization of vocal cords with flexible laryngoscopy before and after exercise to evaluate for presence of inspiratory vocal cord adduction.
Measurements and results: Complete evaluation for all patients consisted of spirometry with flow-volume loops, lung volumes, diffusing capacity, and maximum voluntary ventilation at rest; chest radiograph; methacholine bronchoprovocation testing; and a maximal cardiopulmonary exercise test with expiratory gas analysis. Fifteen percent of patients studied prospectively were found to have VCD, whereas all control subjects were negative for VCD. There was minimal difference in pulmonary function testing between VCD-positive and VCD-negative patients, whereas control subjects had higher spirometric values. Twenty percent of VCD-positive patients had abnormal flow-volume loops compared with 14% of patients without VCD, but after methacholine, 60% of VCD-positive patients developed abnormal flow-volume loops. In the VCD-positive group, 60% had a positive methacholine response, but there was less decrease in FEV(1)/FVC ratio compared with either VCD-negative patients or control subjects.
Conclusions: Paradoxical inspiratory vocal cord closure is a frequent occurrence in patients with symptoms of exertional dyspnea and should be strongly considered in their evaluation.