Respiratory adjuncts to NIV in neuromuscular disease

Muscle weakness is an intrinsic feature of neuromuscular diseases (NMD). When the respiratory muscles are involved, the ability to take a deep breath is compromised, leading to reduced lung volumes and a restrictive ventilatory impairment. Inspiratory, expiratory and bulbar muscle weakness can also impair cough, which may impede secretion clearance. Non-invasive ventilation (NIV) is an established and indispensable therapy to manage hypoventilation and respiratory failure. The role of other therapies that support respiratory health is less clearly defined, and the evidence of efficacy is also harder to summarize as the underlying data are of a lesser quality. This narrative review appraises the evidence for respiratory therapies in adults with NMD and respiratory system involvement. Techniques that assist lung inflation and augment cough, such as lung volume recruitment (LVR) and mechanical insufflation-exsufflation (MI-E), are a particular focus of this review. The evidence suggests that LVR, MI-E and various combinations thereof have clinical utility generally, but important methodological limitations limit the strength of clinical recommendations and hamper the integration of evidence into practice. Future trials should prospectively assess the long-term impact of LVR and cough augmentation on clinical outcomes and burden of care in addition to lung mechanics, as well as determine clear predictors of benefit from these techniques.