From: Respiratory mechanics and ventilatory control in overlap syndrome and obesity hypoventilation
Overlap | Obesity hypoventilation syndrome | |
---|---|---|
Coexistent OSA | No causal relationship | Causal relationship in 90% of the cases |
Hypoventilation (PaCO 2 ≥ 45 mmHg) | Occasionally | Always (by definition) |
Obesity (BMI ≥ 30 kg/m 2 ) | Often (but not obligatory) | Always (by definition) |
Coexistent COPD | Always (by definition) | Never (exclusion by definition) |
Coexistent restrictive pulmonary disease | Occasionally mixed pattern | Often present |
FRC | Decreased | Decreased |
Chemosensitivity (HCVR) | Normal, enhanced or decreased | Decreased |
Leptine resistance | Present | Present |
Hypoxemia pattern | Intermittent (intermittent and chronic in severe cases) | Intermittent and chronic (90%), or chronic (10%) |
Level of hypoxemia | Absent to very severe disturbance | Moderate to very severe disturbance |
Prevalence in general population | 1-4% | 0.37% |
Prevalence in OSA | 10% | 14% |
Pulmonary hypertension | + to ++ | ++ to +++ |
Health care consumption | Increased | Increased |
Mortality | 80% in 12 years | 23% in 1.5 years |
90% in 8 years in LTOT |