The most appropriate treatment is to start long-term oxygen therapy (LTOT) for greater than 15 hours per day. The need for oxygen therapy should be evaluated in all stable patients with an FEV₁ less than 35% of predicted or in patients with clinical symptoms or signs suggestive of respiratory failure or right-sided heart failure. LTOT is indicated if patients meet the following criteria: (1) chronic respiratory failure and/or severe resting hypoxemia, defined as an arterial PO₂ less than or equal to 55 mm Hg (7.3 kPa) or oxygen saturation less than or equal to 88% breathing ambient air, with or without hypercapnia; and/or (2) if there is evidence of pulmonary hypertension, peripheral edema suggesting right-sided heart failure, or polycythemia, in combination with an arterial PO₂ less than or equal to 59 mm Hg (7.8 kPa) or oxygen saturation less than or equal to 89% breathing ambient air. This patient's examination findings (loud pulmonic component of S₂, peripheral edema) and estimated mean pulmonary artery pressure of 52 mm Hg on echocardiography indicate the presence of pulmonary hypertension. Therefore, this patient is an appropriate candidate for LTOT. The resting arterial PO₂ or oxygen saturation values should be repeated and confirmed twice over a 3-week period before a decision about LTOT is made in a stable patient.

A short course of systemic glucocorticoids is recommended in the treatment of acute exacerbations of COPD. However, long-term therapy with systemic glucocorticoids is associated with significant side effects and is not recommended in the management of COPD.

Nocturnal oximetry may be useful in diagnosing hypoxia occurring overnight in patients with COPD that might benefit from oxygen therapy while sleeping. However, this patient's indication for continuous LTOT may be established with available data; therefore, an overnight pulse oximetry study would not be needed to guide therapy.

Although pulmonary rehabilitation is helpful in improving quality of life in patients with advanced COPD, this patient has completed therapy on two occasions, and repeating pulmonary rehabilitation would not address her hypoxemia-associated pulmonary hypertension. However, after LTOT is started, entering a pulmonary rehabilitation program might be appropriate.