Factors influencing severity of obesity hypoventilation syndrome: a proposal for classification based on disease control
| Controlled | Partly controlled | Uncontrolled | |
| Pa,CO2 mmHg | Normal | 46–60 | >60 |
| Pa,O2 mmHg | Normal | Normal | <60 |
| Tolerance of NIV | Yes | Partial | No |
| Symptoms | No | No, or only nocturnal | Yes |
Pa,CO2: arterial carbon dioxide tension; Pa,O2: arterial oxygen tension; NIV: noninvasive ventilation. 1 mmHg = 0.133 kPa.