Defining obesity hypoventilation syndrome

The definition of obesity hypoventilation syndrome (OHS) proposed by Hart et al 1 raises two questions that we have tried to answer briefly in this letter. First, previous definitions of OHS included obstructive sleep apnoea (OSA); Hart et al have excluded it. Why? OSA is present in most patients with OHS and is partly responsible for the hypercapnia.2 We believe that it is …