Oxygen Saturation

Oxygen saturation is a term used to define how much oxygen your blood is carrying. An estimate of your oxygen level can be easily measured with a pulse oximeter, a non-invasive device that attaches to the end of your finger. A more accurate method of measuring oxygen levels is with an arterial blood gas (ABG) study, a blood test that is performed by taking a blood sample from an artery, usually in your wrist. When oxygen levels are measured by pulse oximetry, it’s referred to as SaO2. When they’re measured by an ABG study, it’s referred to as PaO2. Your body needs a specific balance of oxygen in the blood at all times to function properly. When that balance is disturbed, every cell, tissue and organ of your body begin to deteriorate unless balance is restored.

Understanding Normal Oxygen Saturation

Normal oxygen saturation, as measured by pulse oximetry, are 95 to 100%. Normal oxygen levels, as measured by an ABG study, are approximately 75 to 100 millimeters of mercury (mm Hg). In general, values at or below 88% or 55 mm Hg indicate the need for supplemental oxygen (oxygen therapy). There are some people whose oxygen saturation levels remain normal most of the time, but drop only during exercise or sleep. They too may benefit from oxygen therapy during these specific times.

Hypoxemia (Low Blood Oxygen Levels)

When your oxygen saturation drops below normal for an extended period of time, a condition known as hypoxemia can occur. Hypoxemia (low oxygen levels in the blood) can lead to hypoxia (low oxygen levels in the tissues). Hypoxemia is common in people with COPD and other lung conditions such as lung cancer, pneumonia, bronchitis and asthma. Hypoxemia can also be caused by anemia, certain medications that depress breathing and a sleep disorder known as sleep apnea. The most common symptom of hypoxemia is dyspnea (shortness of breath). Other symptoms include headache, confusion, restlessness and anxiety. As hypoxemia worsens, heart rate and blood pressure may increase as your circulatory system tries to compensate for the lack of oxygen in the blood. Untreated, hypoxemia can lead to severe consequences, including death. Because it responds well to oxygen therapy, the standard treatment for hypoxemia is supplemental oxygen.]

When to Call Your Doctor

If you check your oxygen saturation regularly at home with a pulse oximeter, it’s important to note that a transient drop in your oxygen level is not dangerous. When your oxygen levels drop repeatedly or continuously, however, it’s important that you contact your doctor as soon as possible. It’s also essential to see your doctor if you experience:

• Shortness of breath at rest or with a minimal amount of activity.
• Shortness of breath during exercise.
• Abrupt interruptions of sleep accompanied by shortness of breath or a feeling that you’re choking (possible symptoms of sleep apnea).

Seek emergency medical attention:

• If your shortness of breath comes on suddenly and is severe enough to affect your ability to function.
• Severe shortness of breath accompanied by a cough, rapid heartbeat and fluid retention when at altitudes above 8,000 feet. These signs and symptoms are indicative of a condition known as high-altitude pulmonary edema which can be fatal.

Managing Shortness of Breath at Home

If you have ongoing shortness of breath, certain lifestyle changes may improve your breathing. These include:

• Smoking cessation – if you have a lung condition like COPD, quitting smoking is the single most important thing you can do to improve your lung function.
• Avoiding secondhand smoke – secondhand smoke, or passive smoke, can cause further lung damage and worsen lung function. Avoid places where other people are smoking.
• Getting regular exercise – because regular exercise can improve your overall strength and endurance, it can also lessen your shortness of breath. If exercising on your own is difficult, talk to your doctor about beginning a pulmonary rehabilitation program.

For more information, read Pulse Oximetry and Oxygen Saturation: What Oxygen Therapy Users Need to Know.   _{Source: Mayo Clinic. Hypoxemia (Low Blood Oxygen). Updated December 25, 2015.}