Acute effects of assisted cough technique on cardiac autonomic function in patients with Duchenne muscular dystrophy

Abstract

Objective: This study investigated the effects of mechanical insufflation-exsufflation (MI-E) for cough assistance in Duchenne’s muscular dystrophy (DMD) patients and healthy controls and the association of cardiac autonomic function with pulmonary function and body composition. Methods: This cross-sectional study enrolled 28 subjects with DMD (15.8±4.0 years) and 10 age-matched healthy subjects (13.1±3.6 years) that were subjected to three intervention phases: pre-intervention, during the MI-E, and post-intervention. Electrocardiograms of short (5 minutes) were made at each stage. Pulmonary function testing (spirometry, respiratory
muscle strength, thoracic mobility, peak cough flow) and analysis of body composition (anthropometry, bioimpedance) were also performed. Results: Significant multivariate main effects were observed for HRV parameters for the group (Wilk lambda = 0.528, F (13,75) = 5.149, P <0.001, η2 = 1.000) and intervention phase (lambda = Wilk 0.474, F (26,150) = 2.609, P <0.001, η2 = 1.000), but no significant interaction effect. Ventilatory parameters of spirometry were also significantly reduced in DMD patients (p = 0.002 or less). Body anthropometry showed a significant reduction of total body mass, body height and IMC (P<0.050 or less) in patients with DMD. LF was significantly associated with almost all variables of pulmonary function and body composition (0,383 - 0,618). HF was significantly associated with PImax (-0,323) and body fat percentage (0,382). The LF / HF was also associated with lung function (0,323 - 0,370), but not the body composition. Conclusion: The sympathetic and vagal activity is reduced transiently during MI-E in both DMD patients and as in healthy controls. Cardiac autonomic function is associated with pulmonary function and body composition testing. These results suggest that ME can be considered safe for patients with DMD, further studies evaluating the long-term effects on autonomic function of the heart is important.