**16. Impact of respiratory failure on prognosis in cystic fibrosis**

Despite being a predictable outcome of progressive lung disease, the management of respira‐ tory failure in CF, both hypoxic (Type 1 Respiratory Failure) and hypercapnic (Type 2 Respiratory Failure), is lacking in terms of an evidence base [84]. Prescribing habits for oxygen (nocturnal, ambulatory, or resting) borrow largely from guidelines for other conditions. Hypoxia as a determinant of prognosis therefore has not been assessed, although there are suggestions that patients at higher mortality risk have an association with worsening six minute walk test results [85]. However, baseline hypercapnia has been shown to be an independent risk factor for death, even in patients with an FEV1 greater than 30% predicted [86]. There is a paucity of reliable data regarding the benefits of maintenance non-invasive bilevel positive airway pressure ventilation (BIPAP) in CF. One randomised placebo controlled trial from 2008 [87] did show significant benefits with nocturnal BIPAP in terms of symptoms (quality of life questionnaires scores, dyspnoea indices, and chest symptoms), improvements in modified shuttle walk test distances, and improved nocturnal (but not diurnal) arterial hypercapnia, but no significant improvements were shown in lung function. Data does suggest, however, that in the setting of acute respiratory failure requiring admission to intensive care units, non-invasive ventilation (NIV) was associated with significantly im‐ proved outcomes when compared to intubation and mechanical ventilation in patients with CF [88-90]. Hence, the importance of respiratory failure in predicting prognosis needs further study in CF.
