Pursed lips breathing improves ventilation in myotonic muscular dystrophy

Objective: To determine the effects of pursed lips breathing on ventilation , chest wall mechanics, and abdominal muscle recruitment in myotonic muscul ar dystrophy (MMD). Design: Before-after trial. Setting: University hospital pulmonary function laboratory. Participants: Eleven subjects with MMD and 13 normal controls. Intervention: Pursed lips breathing. Outcome Measures: Electromyographic (EMG) activity of the transversus abdom inis, external oblique, internal oblique, and rectus abdominis was recorded with simultaneous measures of gastric pressure, abdominal plethysmography, and oxygen saturation. Self-reported sensations of dyspnea, respiratory ef fort, and fatigue were recorded at the end of each trial. Results: Pursed Lips breathing and deep breathing led to increased tidal vo lume, increased minute ventilation, increased oxygen saturation, reduced re spiratory rate, and reduced end-expiratory lung volume. Dyspnea, respirator y effort, and fatigue increased slightly with pursed lips breathing. EMG ac tivity of the transversus abdominis and internal oblique muscles increased in MMD only and was associated with an increase in gastric pressure. Conclusions: Pursed lips breathing and deep breathing are effective and eas ily employed strategies that significantly improve tidal volume and oxygen saturation in subjects with MMD. Abdominal muscle recruitment does not expl ain the ventilatory improvements, but reduced end-expiratory lung volume ma y increase the elastic recoil of the chest wall. Further clinical studies a re needed to ascertain if the ventilatory improvements with pursed lips bre athing and deep breathing improve pulmonary outcomes in MMD.