Obesity Hypoventilation Syndrome

Obesity Hypoventilation Syndrome (OHS) is a serious breathing problem that affects people with severe obesity. Extra body weight — particularly around the chest and abdomen — makes it physically harder to breathe deeply, leading to low oxygen and high carbon dioxide levels in the blood. People with OHS often feel tired during the day, have morning headaches, and may snore heavily because it frequently occurs alongside sleep apnoea.

Obesity Hypoventilation Syndrome is defined by the triad of obesity (BMI ≥30 kg/m²), daytime hypercapnia (PaCO₂ >45 mmHg), and sleep-disordered breathing in the absence of other causes of hypoventilation. Pathophysiology involves mechanical loading of the respiratory system by central adiposity reducing chest wall compliance, leptin resistance blunting central respiratory drive, and impaired ventilatory responses to hypercapnia and hypoxia. OHS carries significantly higher morbidity and mortality than eucapnic obesity, including increased rates of pulmonary hypertension, right heart failure, and cardiovascular events.

OHS is both underdiagnosed and treatable — weight loss is the cornerstone intervention, often combined with positive airway pressure therapy. Dr Joseph Wang at Accord Medical screens at-risk patients and coordinates multidisciplinary care, as successful weight reduction can reverse hypoventilation and dramatically improve quality of life.