Non-invasive ventilation (NIV) has been one of the major advances in respiratory medicine in the last decade. In particular it has found widespread application in the management of patients with COPD. There is a robust evidence base for its use in acute exacerbations of COPD. The evidence that it is effective in chronic COPD is much less strong but despite this COPD is one of the major reasons for long-term home mechanical ventilation. This chapter focuses mainly on non-invasive ventilation in acute exacerbations of COPD, but also reviews the evidence in chronic ventilatory failure due to COPD.
For ventilation to be effective the respiratory muscle pump must have the capacity to sustain ventilation against a given load, with sufficient drive from the central nervous system. In patients with COPD the primary abnormality leading to the development of ventilatory failure is that of increased load, due to airways obstruction. However the capacity of the respiratory muscle pump may also be reduced, either because the respiratory muscles are working at a mechanical disadvantage as a consequence of hyperinflation1 or because of intrinsic