Q:Which patients with chronic obstructive pulmonary disease (COPD) benefit most from long-term oxygen therapy?
A:Long-term oxygen therapy (LTOT) improves both the length and quality of life of hypoxemic patients with COPD.1,2 It is the only therapy that clearly increases survival for selected patients with advanced stable COPD.1
LTOT is prescribed both for patients with exacerbations of COPD and for those with advanced disease.
Exacerbations of COPD. LTOT may be prescribed for hypoxemic patients at discharge from the hospital following an acute exacerbation. Hypoxemia is defined as a resting arterial oxygen saturation (SaO2) of 88% or less, which corresponds to a partial pressure of arterial oxygen (PaO2) of 55 mm Hg or less. Many hypoxemic patients recover sufficient lung function so as not to need oxygen for physiologic indications. After about 60 to 90 days of LTOT, retest these patients once they have not received oxygen for 20 minutes to determine if significant hypoxemia is still present. In many patients, LTOT can be discontinued if normoxia is found with pulse oximetry or, better yet, arterial blood gas analysis.
Advanced disease. The second group of candidates for LTOT are those with stable advanced COPD characterized by compelling symptoms, such as dyspnea on exertion, evidence of right-sided heart failure, or morning headache. 3,4 These patients are typically being treated with a maintenance regimen of inhaled bronchodilators (anticholinergics, β-agonists, or both); theophylline(Drug information on theophylline) when appropriate; and, often, inhaled corticosteroids.
Patients with an SaO2 of 88% or less and a PaO2 of 55 mm Hg or less qualify for third-party reimbursement (Table). Reimbursement is also allowed for an SaO2 as high as 89% if a patient has secondary polycythemia with a hematocrit of 55% or more or clinical signs of cor pulmonale (verified on chest radiography and ECG).
Once a patient with chronic stable COPD requires oxygen, he or she will need it for life. There is no need to retest for hypoxemia after LTOT has been administered for months. Because oxygen is a potent bronchodilator and vasodilator, it has a restorative effect in some patients. Thus, if LTOT improves ventilation/perfusion matching, room-air PaO2 may rise. It is as inappropriate to withhold oxygen from patients with this successful outcome as it would be to withhold insulin from a patient with diabetes after blood glucose is controlled or to withhold systemic antihypertensives after serious hypertension is controlled.