ABSTRACT
Chronic obstructive pulmonary disease (COPD) is the most common cause of respiratory failure worldwide and is associated with considerable morbidity and mortality (1,2). The aim of pharmacologic therapy is to alleviate symptoms by reversing correctable abnormalities, but in many patients the changes are largely irreversible. In time, patients develop respiratory failure, pulmonary hypertension, and cor pulmonale. Once peripheral edema supervenes, the prognosis is very poor with a 5-yr mortality of between 70 and 100% (3). Therefore various therapeutic strategies have been developed to treat the consequences of chronic airway obstruction in an attempt to improve survival and reduce symptoms. These include long-term oxygen therapy (LTOT), respiratory stimulant drugs, and mechanically assisted ventilation.
