• ABCA3
• Non invasive ventilation

Home non-invasive ventilation (NIV) has been used to manage chronic respiratory failure since the polio epidemics of the 1940s; however, the support for many of the indications remains based on small non-randomised or uncontrolled studies. Obesity hypoventilation syndrome (OHS) is an increasingly common cause of chronic respiratory failure and indication for home mechanical ventilation; unsurprisingly as the diagnosis remains frequently missed, significant variation exists across Europe.1 ,2 The majority of patients with OHS have significant obstructive sleep apnoea (OSA) and recent data have demonstrated the benefits of NIV in a randomised controlled trial.3 ,4 However, it has been increasingly clear that the clinical description which was first reported over 60 years ago5 is in fact made up of distinct clinical phenotypes, most frequently divided by the nature of the sleep-disordered breathing, which is driving respiratory failure.6 In fact, the broad definition is being challenged further with suggestions to incorporate base excess rather than arterial carbon dioxide in the diagnostic criteria and to consider daytime normocapnic subjects with a base excess ≥2 mmol/L as having an early obesity-related nocturnal hypoventilation.7 Analogous to the phenotypes being increasingly advocated in COPD,8 the subdivisions of OHS may have different risk profiles and require differing treatment strategies.

Masa et al9 present data in this edition of Thorax on …