Supplemental medical oxygen is classified as a drug by regulatory bodies, making a prescription from a qualified healthcare provider mandatory for home use. This classification ensures it is administered only when a medical need exists and at the correct dosage. Because oxygen acts as a medication, its use is reserved for treating conditions that cause dangerously low levels of oxygen in the blood. Obtaining this prescription is a systematic process focused on establishing medical necessity through objective testing.
Establishing Medical Necessity: Required Testing and Criteria
Securing an oxygen prescription requires objective evidence that the body’s oxygen levels are consistently or intermittently too low, a condition known as hypoxemia. Healthcare providers use specific diagnostic tools and criteria to confirm this need, primarily relying on pulse oximetry and arterial blood gas (ABG) analysis. The initial screening often involves pulse oximetry, a non-invasive test that measures the oxygen saturation of the blood (SpO2) while the patient is at rest and breathing room air.
To qualify for long-term home oxygen therapy, the SpO2 level must generally be documented at 88 percent or lower. This threshold is a key indicator of significant hypoxemia and is often used by insurance providers to determine coverage. A slightly higher saturation, such as 89 percent, may still qualify the patient if they also show evidence of organ strain, such as cor pulmonale, congestive heart failure, or erythrocytemia.
For the most definitive measurement, an Arterial Blood Gas (ABG) test is performed, which directly measures the pressure of oxygen dissolved in the blood (PaO2). A patient typically qualifies for therapy if their PaO2 value is measured at 55 mmHg or less while at rest and breathing room air. Similar to the oximetry rules, a PaO2 between 56 mmHg and 59 mmHg may also qualify the patient if there is documented evidence of associated conditions like pulmonary hypertension or right-sided heart failure.
Hypoxemia does not always occur at rest, so testing may also be required during specific activities like sleep or exercise. For example, a patient may qualify for nocturnal oxygen if an overnight oximetry study shows a saturation of 88 percent or less for a cumulative period of at least five minutes. Similarly, oxygen may be prescribed for use during physical activity if a walking test demonstrates the SpO2 falls to 88 percent or lower. The application of supplemental oxygen must also prevent this desaturation during the test. These requirements ensure that the therapy is provided to treat underlying conditions such as severe Chronic Obstructive Pulmonary Disease (COPD) or pulmonary fibrosis.
Securing the Prescription: The Role of the Physician
Once medical necessity has been established through the required testing, the treating physician generates the formal prescription, which is a detailed medical order. This prescription is often written by specialists such as pulmonologists or cardiologists, or by the primary care physician managing the patient’s long-term care. The written order must contain several specific details to be considered valid for obtaining the equipment and coverage.
The physician must first document the qualifying diagnosis, such as severe COPD, along with the specific laboratory test results that confirm the hypoxemia. Crucially, the prescription must specify the exact flow rate of the oxygen, measured in liters per minute (LPM), and the duration of use (e.g., 24 hours a day, nocturnal, or only during exertion). The prescribed method of delivery, such as a nasal cannula or a mask, must also be included in the written order.
An oxygen prescription is not indefinite; it often requires periodic re-evaluation and recertification. Initial prescriptions for long-term use may be limited to a specific period, such as one year. After this period, the physician must conduct a follow-up assessment and, in some cases, repeat the blood gas testing. This process ensures the oxygen dosage remains appropriate for the patient’s current clinical status.
Logistics of Home Oxygen Therapy: Equipment and Setup
After the physician secures the prescription, the process moves to the practical logistics of providing the equipment for home use. This is primarily handled by a Durable Medical Equipment (DME) supplier, a specialized company that provides and maintains medical devices. The DME supplier works with the prescribing physician and the patient to select the most appropriate oxygen system based on the flow rate and duration of use specified in the prescription.
The most common equipment option is a stationary oxygen concentrator, which plugs into an electrical outlet and filters oxygen from the surrounding air for continuous home use. For patients who need to remain mobile, the supplier may provide a portable oxygen concentrator (POC) or small compressed gas tanks. Liquid oxygen systems are another option, storing a large volume of oxygen in a compact form, though they are less common than concentrators.
The DME supplier is responsible for the delivery and professional setup of the equipment in the patient’s home. This setup includes providing necessary accessories, such as tubing and nasal cannulas, and comprehensive training to the patient and caregivers. This training covers proper operation, routine maintenance, and safety protocols. Patients are given strict instructions regarding fire hazards, including maintaining a safe distance from heat sources and never smoking while using the equipment.