Chronic Obstructive Pulmonary Disease (COPD) encompasses progressive lung conditions that make breathing increasingly difficult. These conditions, primarily emphysema and chronic bronchitis, cause irreversible damage to the airways and air sacs within the lungs, leading to airflow obstruction. This damage can involve a loss of elasticity in the air sacs, inflammation and narrowing of airways, or excessive mucus production. Understanding when supplemental oxygen therapy becomes a necessary part of managing COPD is important.
How COPD Severity is Measured
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) provides a standardized system for classifying COPD severity. This system relies on spirometry, a lung function test measuring how much air a person can exhale and how quickly. A key measurement is the forced expiratory volume in one second (FEV1), the amount of air exhaled in the first second of a forced breath, and the forced vital capacity (FVC), the total air exhaled. A post-bronchodilator FEV1/FVC ratio below 0.7 confirms airflow limitation, diagnostic for COPD.
COPD severity is further categorized into GOLD stages 1 through 4 based on the FEV1 percentage of the predicted value. GOLD 1 indicates mild disease with an FEV1 of 80% or more, while GOLD 4 signifies very severe COPD, where FEV1 is less than 30% of the predicted value. Beyond spirometry, the GOLD system also considers a patient’s symptoms and history of exacerbations, or flare-ups, for a comprehensive assessment. While these stages indicate the degree of airflow limitation, the need for oxygen therapy is determined by specific physiological criteria rather than solely by a particular GOLD stage.
When Oxygen Therapy Becomes Necessary
The decision to prescribe supplemental oxygen therapy for COPD patients hinges on specific medical criteria. Healthcare providers assess these levels using arterial blood gas (ABG) measurements and pulse oximetry. ABG tests measure the partial pressure of oxygen in arterial blood (PaO2), while pulse oximetry estimates oxygen saturation (SpO2) in the blood.
Long-term oxygen therapy (LTOT) is typically considered when a patient’s PaO2 falls to 55 millimeters of mercury (mmHg) or lower, or their SpO2 is consistently at or below 88% while breathing room air. In some cases, oxygen may be indicated at a slightly higher PaO2 of 56-59 mmHg or SpO2 of 89% if there are additional signs of tissue oxygen deprivation. These signs can include right-sided heart failure (cor pulmonale), an increased red blood cell count (polycythemia), or peripheral edema (swelling).
Oxygen therapy may also be necessary if oxygen levels drop significantly during sleep or with physical exertion. A doctor’s assessment, including comprehensive testing, determines the need for oxygen. Oxygen is a treatment for hypoxemia, or low blood oxygen, and not merely for the symptom of breathlessness. Reassessment of oxygen needs after 60 to 90 days is often recommended, especially if oxygen was initiated following a COPD exacerbation.
The Purpose of Supplemental Oxygen
Supplemental oxygen’s purpose is to provide the body with adequate oxygen to support organ function and improve overall well-being. It helps alleviate the strain on the heart, particularly in preventing or managing cor pulmonale, a condition where the right side of the heart is affected by lung disease. This therapy reduces the heart’s workload and enhances its function by improving oxygen levels.
Patients often experience improved shortness of breath and an increased ability to perform daily activities. This can lead to better exercise tolerance and an improved quality of life. Adequate oxygenation can contribute to better sleep patterns and improved cognitive function. While oxygen therapy significantly manages symptoms and improves outcomes for those who qualify, it does not cure COPD.