To the Editors:
Obesity hypoventilation syndrome (OHS) is commonly defined as a combination of obesity (body mass index (BMI) >30 kg·m−2), waking arterial hypercapnia (arterial carbon dioxide tension (Pa,CO2) >6.0 kPa (45 mmHg)) and sleep-disordered breathing. Essential to the diagnosis is exclusion of other causes of alveolar hypoventilation 1. The lack of a standardised definition of OHS in general, and of OHS–obstructive sleep apnoea relationships in particular, leads to confusion.
One of the main aspects that has not been clarified is the assessment of OHS severity. This appears to be directly related to the degree of hypercapnia, the degree of hypoxaemia and the presence of complications 2, 3. Nevertheless, …
