American Board of Internal Medicine (ABIM) Certification Practice Exam

Under what conditions is long-term oxygen therapy indicated for patients with COPD?

1. Severe resting hypercapnia

2. Moderate dyspnea without hypoxemia

3. Chronic respiratory failure and/or severe hypoxemia

4. Frequent acute exacerbations

The correct answer is: Chronic respiratory failure and/or severe hypoxemia

Long-term oxygen therapy is indicated for patients with Chronic Obstructive Pulmonary Disease (COPD) primarily under conditions of chronic respiratory failure and/or severe hypoxemia. Patients with COPD may develop low oxygen levels in the blood (hypoxemia) due to progressive lung damage. When the oxygen saturation is significantly low (usually a partial pressure of oxygen in arterial blood less than 55 mmHg or oxygen saturation below 88% at rest), it can lead to important physiological changes, including increased pulmonary hypertension, right heart failure, and increased morbidity and mortality. Long-term oxygen therapy helps to improve survival rates in these patients, enhances their quality of life, and can reduce hospitalizations due to exacerbations. The therapy is typically administered for a minimum of 15 hours daily, including overnight, to maintain adequate oxygen levels and minimize complications associated with persistent hypoxemia. While conditions such as severe resting hypercapnia can complicate the management of COPD, the primary driver for oxygen therapy is the need to correct hypoxemia. Moderate dyspnea without hypoxemia and frequent acute exacerbations indicate issues with disease severity or management but do not automatically necessitate long-term oxygen therapy unless they are associated with hypoxemia. Thus, the combination of