Acute effects of mechanical insufflation-exsufflation on the breathing pattern in stable subjects with duchenne muscular dystrophy

Abstract

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.