LAUSR

Introduction: Individuals with idiopathic persistent exertional dyspnoea are often labelled as having dysfunctional breathing (DB). Pathophysiological mechanisms underpinning DB are poorly understood. Patients with DB appear to have abnormal periodic ventilatory irregularities that manifest during cardiopulmonary exercise testing (CPEX). We sought to describe and characterise these irregularities. Methods: Retrospective case-control study on 183 consecutive patients attending a specialist “unexplained breathlessness” clinic from 2013-16. An independent physiologist reviewed the CPEX data. Physiological data were compared between the groups based on ventilatory pattern (Figure 1). Results: 55 subjects were included with mean (SD) age 48 (15) yrs, 69% female and mean (SD) BMI 28 (5) kgm-2. Regular oscillatory ventilatory alterations were apparent in 32 (58%) of whom were 65% female. Of these 32 patients 9 (28%) fulfilled the criteria for exercise oscillatory ventilation (EOV). No significant differences between characteristics of patients demonstrating oscillatory abnormalities. Conclusion: In DB, there appears to be a high prevalence of oscillatory ventilatory abnormalities and one fifth of patients fulfil the accepted criteria for EOV. Further study evaluating the factors controlling modulation of ventilatory oscillation is important. Figure1.Ventilatory patterns during CPEX;a.Normal; b. Abnormal periodic ventilation; c.+EOV.