Supplemental oxygen therapy delivers supplemental oxygen to the lungs and is used for patients with significant hypoxemia. Long-term oxygen therapy has been shown to improve survival in patients with severe resting hypoxemia.
Supplemental oxygen therapy may be used during pulmonary rehabilitation to relieve breathless in patients who desaturate during exercise during testing.
Before oxygen is administered, oxygenation should be assessed by pulse oximetry or arterial blood gas measurements (ABG). Oxygen delivery can then be titrated over time using oximetry.
Indications for Supplemental Oxygen
Some patients with chronic lung disease require short-term oxygen therapy during an acute exacerbation of their lung disease, whereas others with persistent hypoxemia (eg, patients with severe chronic obstructive pulmonary disease [COPD]), may require long-term oxygen therapy.
The primary indications for oxygen therapy in the acute setting include (1):
Acute severe hypoxemia (partial pressure of arterial oxygen [PaO2] < 55 mm Hg or oxygen saturation [SpO2] ≤ 88%)
Suspected hypoxemia with associated cardiorespiratory distress
Acute hypoxemia can occur secondary to acute hypoxemic respiratory failure (AHRF), or ventilatory failure (eg, exacerbations of asthma, COPD, infectious processes such as pneumonia). Other situations in which oxygen therapy may be required in the acute setting include:
Severe trauma
Low cardiac output with metabolic acidosis
Carbon monoxide poisoning
Indications for chronic oxygen therapy include (1):
Severe resting hypoxemia (PaO2 ≤ 55 mm Hg or SpO2 ≤ 88%)
Resting hypoxemia (PaO2 56 to 59 mm Hg or SpO2 = 89%) in cor pulmonale, pulmonary hypertension, or polycythemia
Severe exertional hypoxemia (defined as oxygen saturation measured by pulse oximetry [SpO₂] ≤ 88% during exercise) may necessitate supplemental oxygen during exertion such as pulmonary rehabilitation
The most common causes for resting hypoxemia include COPD, interstitial lung disease (eg, idiopathic pulmonary fibrosis), cystic fibrosis. and severe bronchiectasis. Chronic right-sided heart failure may also cause resting hypoxemia. For patients with longstanding, severe (but not moderate) hypoxemia, long-term oxygen therapy improves survival (2, 3), particularly when used for ≥ 15 hours per day (4). It may also reduce dyspnea and cardiac strain related to pulmonary disease and improve quality of life, pulmonary function, and exercise capacity (5).
Patients with exertional or nocturnal hypoxia may limit their oxygen use to overnight hours.
(See also Oxygen Therapy for Stable COPD and Pulmonary Rehabilitation.)
Indications for supplemental oxygen use references
1. Wemple ML, Swenson KE, Swenson ER. Oxygen Therapy Part 2 - Indications and Toxicity. NEJM Evid. 2023;2(7):EVIDra2300111. doi:10.1056/EVIDra2300111
2. Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease: a clinical trial. Nocturnal Oxygen Therapy Trial Group. Ann Intern Med. 1980;93(3):391-398. doi:10.7326/0003-4819-93-3-391
3. Long-Term Oxygen Treatment Trial Research Group, Albert RK, Au DH, et al. A Randomized Trial of Long-Term Oxygen for COPD with Moderate Desaturation. N Engl J Med. 2016;375(17):1617-1627. doi:10.1056/NEJMoa1604344
4. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Diagnosis and assessment. Global Strategy for the Prevention, Diagnosis, and Management of COPD: 2026 report.
5. Muge Q, Suriguga, Yuqing, Aronggaowa, Taojin, Chen L. A meta-analysis of the effects of long-term oxygen therapy combined with exercise rehabilitation on exercise capacity, cardiopulmonary function, and quality of life in patients with COPD. Front Med (Lausanne). 2025;12:1640084. doi:10.3389/fmed.2025.1640084
Oxygen Delivery Systems
Oxygen for long-term home use is available from 3 different delivery systems:
Oxygen concentrators
Compressed gas systems
Liquid oxygen systems
An oxygen concentrator removes nitrogen from ambient air, producing oxygen-enriched gas. Because the system draws from the room air, no oxygen tank deliveries or refills are required.
Photograph depicting a hospitalized patient receiving oxygen therapy with a concentrator with a power button, display monitor, and attachments for the oxygen tank (including both inflow and outflow tubes from the tank). The dial on the bottom left is a flow meter knob used to titrate oxygen flow (typically in liters per minute).
Galka3250/stock.adobe.com
With a compressed gas system, oxygen is stored under pressure and is released as the patient inhales.
Inside the home, compressed gas systems use large tanks to store oxygen. These tanks are periodically refilled by a home care company. Small, portable tanks of compressed oxygen or a portable oxygen concentrator may be used outside the home.
Oxygen sources should be closed tightly when not in use. Because oxygen is an oxidizer that accelerates combustion, it can cause materials that would not normally ignite in room air to burn rapidly or explode. Thus, it is important to keep tanks away from any sources of ignition.
With a liquid oxygen system, oxygen is stored in liquid form at very low temperatures in a stationary reservoir (that can be kept at home), with smaller portable canisters that are refilled directly from the reservoir for ambulatory use. The liquid oxygen vaporizes to gas before delivery to the patient and does not require electricity, but it does require periodic refilling. Liquid oxygen systems are rarely used for home use due to the high cost and higher convenience of other methods.
Oxygen Administration
Oxygen is typically administered through a nasal cannula with either continuous flow or pulsed-flow delivery. To improve efficiency and increase mobility in patients requiring high amounts of supplemental oxygen, several devices, including reservoir cannulas, can be used. When the patient exhales, a reservoir cannula stores oxygen in a small chamber, and then returns the oxygen when the patient inhales.
Demand-type systems deliver oxygen only when triggered by the machine's user (such as when the patient inhales or presses on the device). They do not deliver oxygen continuously. Some have small reservoirs.
