Long-term Continuous Oxygen Treatment in COPD
Long-term Continuous Oxygen Treatment in COPD
Purpose of Review: Long-term oxygen treatment is one of the few interventions that improve survival in chronic obstructive pulmonary disease and it is widely used even though published evidence supporting the use of this treatment in chronic obstructive pulmonary disease is scanty. In addition, some studies do not demonstrate a mortality benefit for long-term oxygen treatment in this disease. It is important that long-term oxygen treatment be administered only to those patients who will benefit and in a manner that maximizes its efficacy. New studies are urgently needed to address these questions.
Recent Findings: The published evidence for and against the use of long-term oxygen treatment in chronic obstructive pulmonary disease is summarized and problems with current guidelines and important areas for future research are discussed.
Summary: Future research will address the optimal timing and duration of oxygen therapy during rest, exercise and sleep, ways of identifying chronic obstructive pulmonary disease patients who are most likely to benefit and ways of improving patient compliance, all of which may have a profound effect on clinical practice.
Chronic obstructive pulmonary disease (COPD) kills approximately 120 000 Americans per year and is expected to be the third leading cause of death worldwide by 2020. Pharmacotherapy for COPD, such as inhaled bronchodilators and corticosteroids, improves symptoms in randomized controlled trials but has not been demonstrated to prolong survival. Some interventions, however, have been identified that likely prolong the survival of patients with COPD. Retrospective studies suggest that pneumococcal and influenza vaccinations reduce mortality in patients with COPD, but prospective studies are lacking. Intensive management of patients hospitalized for acute exacerbations of COPD, including the use of noninvasive positive pressure ventilation for respiratory failure, probably improves survival. Lung volume reduction surgery has been demonstrated to improve survival in selected patients with severe emphysema. Finally, long-term oxygen treatment (LTOT) has been demonstrated to significantly reduce mortality in patients with COPD and severe, resting arterial hypoxemia. Of all these interventions, LTOT has the greatest proven impact on public health.
There is a clear biological rationale for the use of LTOT in severe COPD. Enhancing blood oxygenation by increasing the concentration of inspired oxygen compensates for a major physiological consequence of COPD with hypoxemia. The benefits of this treatment may exceed the simple, metabolic effects of increased oxygen delivery, however. Oxygen modifies many physiological and molecular processes throughout the body. COPD patients with severe hypoxemia who receive chronic oxygen treatment demonstrate reduced alveolar-arterial oxygen gradients and pulmonary artery pressures, suggesting that oxygen may affect remodeling or repair of the lung. Some studies have suggested improvements with chronic oxygen treatment in other outcome measures in patients with COPD, including depression, cognitive function, quality of life, exercise capability and frequency of hospitalizations. These provide additional important reasons for the use of LTOT.
Purpose of Review: Long-term oxygen treatment is one of the few interventions that improve survival in chronic obstructive pulmonary disease and it is widely used even though published evidence supporting the use of this treatment in chronic obstructive pulmonary disease is scanty. In addition, some studies do not demonstrate a mortality benefit for long-term oxygen treatment in this disease. It is important that long-term oxygen treatment be administered only to those patients who will benefit and in a manner that maximizes its efficacy. New studies are urgently needed to address these questions.
Recent Findings: The published evidence for and against the use of long-term oxygen treatment in chronic obstructive pulmonary disease is summarized and problems with current guidelines and important areas for future research are discussed.
Summary: Future research will address the optimal timing and duration of oxygen therapy during rest, exercise and sleep, ways of identifying chronic obstructive pulmonary disease patients who are most likely to benefit and ways of improving patient compliance, all of which may have a profound effect on clinical practice.
Chronic obstructive pulmonary disease (COPD) kills approximately 120 000 Americans per year and is expected to be the third leading cause of death worldwide by 2020. Pharmacotherapy for COPD, such as inhaled bronchodilators and corticosteroids, improves symptoms in randomized controlled trials but has not been demonstrated to prolong survival. Some interventions, however, have been identified that likely prolong the survival of patients with COPD. Retrospective studies suggest that pneumococcal and influenza vaccinations reduce mortality in patients with COPD, but prospective studies are lacking. Intensive management of patients hospitalized for acute exacerbations of COPD, including the use of noninvasive positive pressure ventilation for respiratory failure, probably improves survival. Lung volume reduction surgery has been demonstrated to improve survival in selected patients with severe emphysema. Finally, long-term oxygen treatment (LTOT) has been demonstrated to significantly reduce mortality in patients with COPD and severe, resting arterial hypoxemia. Of all these interventions, LTOT has the greatest proven impact on public health.
There is a clear biological rationale for the use of LTOT in severe COPD. Enhancing blood oxygenation by increasing the concentration of inspired oxygen compensates for a major physiological consequence of COPD with hypoxemia. The benefits of this treatment may exceed the simple, metabolic effects of increased oxygen delivery, however. Oxygen modifies many physiological and molecular processes throughout the body. COPD patients with severe hypoxemia who receive chronic oxygen treatment demonstrate reduced alveolar-arterial oxygen gradients and pulmonary artery pressures, suggesting that oxygen may affect remodeling or repair of the lung. Some studies have suggested improvements with chronic oxygen treatment in other outcome measures in patients with COPD, including depression, cognitive function, quality of life, exercise capability and frequency of hospitalizations. These provide additional important reasons for the use of LTOT.