Supplemental oxygen is a medical treatment used when the lungs cannot absorb enough oxygen to meet the body’s needs. This lack of adequate oxygen in the blood is known as hypoxemia, a condition that can impair organ function and be life-threatening if left untreated. Oxygen is considered a prescribed medication, meaning a healthcare provider must order it and determine the correct flow rate and duration of use. The decision to use this therapy is based on specific medical criteria indicating the body cannot maintain healthy oxygen levels on its own.
Defining Low Oxygen Thresholds
The need for supplemental oxygen is determined by measuring the amount of oxygen carried in the blood, typically using two metrics. Oxygen saturation (SpO2) measures the percentage of hemoglobin carrying oxygen, usually checked with a non-invasive pulse oximeter clipped to a finger. An SpO2 reading consistently below 90% is a general indicator that supplemental oxygen may be necessary.
The second metric, partial pressure of oxygen (PaO2), is measured from an arterial blood gas sample and provides a more direct reading of oxygen dissolved in the blood. A PaO2 below 60 millimeters of mercury (mmHg) is often a definitive medical threshold for considering oxygen therapy, as this level corresponds closely to an SpO2 of 90% or less. These measurements help clinicians confirm hypoxemia and guide the decision for treatment.
Acute Conditions Requiring Temporary Oxygen
The need for supplemental oxygen is often sudden, severe, and temporary, lasting until an acute medical event is resolved. Conditions causing rapid lung inflammation or fluid buildup severely impair the lungs’ ability to transfer oxygen into the bloodstream. Examples include severe pneumonia, where infection fills the air sacs, and acute exacerbations of asthma or Chronic Obstructive Pulmonary Disease (COPD) causing severe airway constriction.
Temporary oxygen is also routinely administered following major surgery, especially when patients are recovering from anesthesia or have restricted lung function due to pain. Trauma, such as severe chest injuries, or episodes of acute heart failure can also lead to short-term hypoxemia requiring immediate support. The goal is to stabilize the patient by improving oxygen delivery until the underlying condition responds to other treatments, allowing the supplemental oxygen to be gradually weaned off.
Chronic Diseases Necessitating Long-Term Therapy
For individuals with progressive, ongoing respiratory illnesses, supplemental oxygen often becomes a necessary part of daily life, known as long-term oxygen therapy (LTOT). This therapy is typically prescribed for at least 15 hours per day when hypoxemia persists even after the underlying condition has been stabilized with medication. Severe Chronic Obstructive Pulmonary Disease (COPD) is the most common condition requiring LTOT, as damage to the airways permanently limits gas exchange.
Other progressive lung conditions, such as severe pulmonary fibrosis and advanced cystic fibrosis, also necessitate continuous oxygen support. The requirement for LTOT is established when resting PaO2 levels fall to 55 mmHg or less, or SpO2 remains at 88% or below. Long-term oxygen use improves survival rates and quality of life for people with chronic hypoxemia, especially those with COPD. This continuous supply mitigates the strain of low oxygen on the heart and other organs, helping to prevent complications like pulmonary hypertension.
Patients may also be prescribed ambulatory oxygen for use during physical activity or nocturnal oxygen for use only while sleeping. The specific prescription depends on when their oxygen levels drop below acceptable thresholds.
Safety Guidelines for Supplemental Oxygen Use
Because oxygen actively supports combustion, following strict safety guidelines is paramount when using the therapy at home. While oxygen itself is not flammable, it dramatically increases the intensity and speed at which other materials burn during a fire. Patients must never smoke or allow others to smoke near the oxygen equipment, and should post “No Smoking” signs throughout the home.
All sources of open flame, intense heat, and spark-producing electrical devices like hair dryers or electric razors must be kept at least five to six feet away from the oxygen unit and tubing. Use only water-based lotions or creams, as oil-based products like petroleum jelly can react with oxygen and increase the risk of ignition. Patients must never adjust the prescribed flow rate without a doctor’s explicit instruction. Using too much oxygen can be harmful, especially for some patients with chronic lung disease who rely on lower oxygen levels to trigger their breathing drive.