This case is an example of combined oxygenation and ventilatory failure in a patient with severe chronic obstructive pulmonary disease (COPD). COPD encompasses the conditions chronic bronchitis and emphysema and is almost always caused by long-term cigarette smoking. In this case, the patient had emphysema. In emphysema, the pathologic destruction of the alveolar-capillary units results in larger air spaces that are not adequately perfused, resulting in an increase in physiologic dead space. As the disease progresses, the patient is unable to maintain alveolar ventilation, resulting in hypercapnia, hypoxemia, and widened alveolar-arterial (A-a) gradient. The loss of radial traction forces causes airways to close early in patients with emphysema. The patients can breathe air in but have difficulty breathing air out. Their forced expiratory volume in 1 s decreases to less than 35% of predicted. Patients use pursed-lip breathing to increase airway pressure and prevent dynamic compression of airways. Bronchodilator therapy is used to reduce airway resistance and enhance breathing.