Respiratory complications of obesity: from early changes to respiratory failure.

Obesity is a significant and increasingly common cause of respiratory compromise. It causes a decrease in static and dynamic pulmonary volumes. The expiratory reserve volume is one of the first to be affected. Obesity is associated with reduced airflow, increased airway hyperresponsiveness, and an increased risk of developing pulmonary hypertension, pulmonary embolism, respiratory tract infections, obstructive sleep apnoea and obesity hypoventilation syndrome. The physiological changes caused by obesity will eventually lead to hypoxic or hypercapnic respiratory failure. The pathophysiology of these changes includes a physical load of adipose tissue on the respiratory system and a systemic inflammatory state. Weight loss has clear, well-defined benefits in improving respiratory and airway physiology in obese individuals.