Acute Effects of Mechanical Insufflation-Exsufflation on the Breathing Pattern in Stable Subjects With Duchenne Muscular Dystrophy

BACKGROUND: Duchenne muscular dystrophy (DMD) is characterized by progressive degeneration, wasting, and weakness of skeletal musculature, including respiratory muscles. Cough is also compromised with disease progression. Among cough-augmentation techniques, mechanical insufflation-exsufflation (MI-E) has demonstrated several clinical benefits in patients with chronic airway secretion obstruction and muscular weakness. In clinical practice, the use of MI-E in DMD patients is also suggested when they are stable with no airway infections. However, there is a paucity of studies that consider the effect of MI-E specifically on stable DMD patients who have adapted to the use of MI-E. METHODS: Twenty subjects with DMD with no active upper airway or lung infections, who used MI-E device regularly at home, were enrolled. They received a single MI-E treatment consisting of 5 cycles of 5 insufflations-exsufflations with their customary settings. Volume variations during quiet breathing, vital capacity, and cough before and after treatment were measured with optoelectronic plethysmography (OEP). RESULTS: A decrease in breathing frequency ( P = .001) and the rapid shallow breathing index emerged ( P = .007), while cough peak flow (Spirometer P = .86, OEP P = .58), vital capacity (Spirometer P = .78, OEP total chest wall P = .57), and end-expiratory volumes (Total chest wall P = .97, Ribcage P = .14, Abdomen P = .10) were not affected by the treatment. An increment of the chest wall volume variation during the expiratory cough phase was identified ( P = .001), particularly due to an increase in abdominal expansion ( P = .005). CONCLUSIONS: A single treatment of MI-E in subjects with stable DMD already adapted to the device can provide beneficial changes in breathing pattern through a significant decrease in breathing frequency and rapid shallow breathing. These findings suggest an improvement in short-term dyspnea, although there were no changes in lung-volume recruitment or unassisted cough peak flow.