Obesity Hypoventilation Syndrome

Obesity Hypoventilation Syndrome is a condition that affects breathing in people who are significantly overweight. It involves the lungs and the body's ability to get rid of carbon dioxide and take in oxygen properly. People with this condition breathe too shallowly or slowly during sleep and sometimes even when awake, leading to low oxygen levels and high carbon dioxide levels in the blood. This can cause symptoms like daytime sleepiness, headaches, and difficulty concentrating. The extra weight on the chest and abdomen makes it harder for the lungs to expand fully, which worsens breathing problems. Over time, this can strain the heart and lead to serious health issues. Managing this condition is important to improve breathing and overall health.

Obesity Hypoventilation Syndrome (OHS) is defined by chronic daytime hypercapnia (arterial CO2 >45 mmHg) in obese individuals (BMI >30 kg/m2) without other causes of hypoventilation. The core pathology is alveolar hypoventilation due to impaired respiratory mechanics from excess adipose tissue, leading to reduced chest wall compliance and increased work of breathing. This results in chronic hypoxemia and hypercapnia, often accompanied by sleep-disordered breathing such as obstructive sleep apnea. The syndrome is clinically significant because it causes pulmonary hypertension, right heart failure, and increased mortality if untreated. The pathophysiology involves blunted ventilatory drive and respiratory muscle inefficiency. Diagnosis requires exclusion of other causes of hypoventilation such as neuromuscular disease or severe lung disease.