What does blood oxygen level mean?
Your blood oxygen level (oxygen saturation) is the amount of oxygen circulating in your blood.
Oxygen is vital to life, and our bodies require a certain amount of it to function properly. When you breathe, oxygen enters your body through your nose or mouth and into your bloodstream through your lungs. Once in your bloodstream, oxygen travels to cells throughout your body. All of your cells need oxygen to produce energy efficiently, and your body needs energy to complete all of its processes, such as digestion and even thinking.
Once your cells use oxygen, they produce carbon dioxide. Your blood then carries the carbon dioxide back to your lungs, and you exhale it through your mouth or nose.
Your body tightly regulates the oxygen saturation in your blood, because low blood oxygen levels (hypoxemia) can lead to many serious illnesses and cause damage to single organ systems, especially the brain and heart. Low blood oxygen levels indicate that your lungs and/or circulatory system may not be functioning properly.
What does your blood oxygen level show?
Most children and adults do not need to monitor their blood oxygen levels. In fact, many doctors won't test it either unless there are signs of a problem, such as shortness of breath or chest pain.
However, many people with chronic medical conditions need to monitor their blood oxygen levels. This includes asthma, heart disease and chronic obstructive pulmonary disease (COPD).
In these cases, monitoring your blood oxygen levels can help determine whether treatment is working or if adjustments should be made.
Read on to learn where your blood oxygen levels should be, what symptoms you might experience if your levels drop, and what to expect next.
How to measure your blood oxygen levels
arterial blood gas
To perform an ABG measurement, your doctor draws blood from an artery instead of a vein. Unlike veins, arteries have a pulse that can be felt. Additionally, the blood drawn from your arteries is oxygenated, but the blood in your veins is not.
The artery in your wrist is used because it is easier to feel than other arteries in your body.
The wrist is a sensitive area, and drawing blood there is more uncomfortable than from veins near the elbow. The arteries are also deeper than the veins, adding to the discomfort.
Test details
Who performs blood oxygen level testing?
Specialist health care providers, called respiratory therapists, often draw blood to test blood oxygen levels as part of a wrist artery blood gas test. The sample is then either processed by a respiratory therapist or quickly sent to a laboratory where a medical laboratory scientist processes the sample.
Any healthcare provider can use a pulse oximeter to check your blood oxygen saturation levels. You can also use a pulse oximeter on yourself or someone else in your home.
What happens before the blood oxygen level test?
If a respiratory therapist takes a blood sample from an artery in your wrist, they may perform a blood circulation test called an Allen test before taking the sample. The Allen test involves holding your hands in the air with clenched fists. Your provider will then apply pressure to the arteries in your wrist for a few seconds. This simple test ensures that both arteries in your wrist are open and functioning properly.
If you are receiving supplemental oxygen therapy, your provider may turn off the oxygen for about 20 minutes before drawing blood. This is called an indoor air test. Your provider will not perform this test if you cannot breathe without supplemental oxygen.
What should I expect during a blood oxygen level test?
Most blood tests take a blood sample from one of your veins. For a blood oxygen level test as part of an arterial blood gas test, the respiratory therapist will take a blood sample from one of your arteries. This is because the oxygen content in arterial blood is higher than the oxygen content in venous blood.
Respiratory therapists usually take a sample from an artery in the wrist, called the radial artery. Sometimes they may take a sample from an artery in your elbow or groin. If a newborn is being tested for blood oxygen levels, they may collect a sample from the baby's heel or umbilical cord.
Unfortunately, obtaining a blood sample from an artery is often more painful than obtaining a sample from a vein. This is because arteries are deeper than veins and are surrounded by nerves. When the respiratory therapist draws blood from your arteries, you may feel dizzy, dizzy, or nauseous.
Drawing blood for a blood oxygen level test involves the following steps:
- You will sit in a chair or lie on a medical bed, and the respiratory therapist will look for arteries - usually on the inside of your wrist. They may use ultrasound imaging to help find the artery.
- Once the artery is found, they clean and disinfect the area.
- They will then insert a small needle into your artery to take a blood sample. You may feel severe pain when the needle penetrates the artery.
- After the needle is inserted, a small amount of blood collects in the syringe.
- Once there is enough blood to test, they will remove the needle and place cotton balls or gauze in the area to stop the bleeding. If you are taking blood-thinning medications, they may apply pressure for 5 to 10 minutes or longer.
- They'll put a bandage on the wound and you're done.
Performing a blood oxygen saturation test using a pulse oximeter involves the following steps:
- Your healthcare provider will clip a small plastic electronic device called a pulse oximeter to somewhere on your body (usually your fingertips).
- The oximeter will send a special type of light called infrared light that will pass through your skin and into the blood in your capillaries. It's harmless and you won't feel anything.
- The oximeter then measures the amount of light reflected by the heme molecules in the blood. This is used to determine your blood oxygen levels.
- After a few seconds, the oximeter will provide numbers corresponding to your heart rate and oxygen levels.
You can also use a pulse oximeter at home. It is important to remember factors that may reduce the accuracy of pulse oximeter readings, including:
- Apply nail polish to the finger or toe you want to test.
- The room where the oximeter is used has high-intensity lighting.
- Use an oximeter for excessive exercise.
What should I expect after a blood oxygen level test?
If you have had your blood drawn, you may experience some bruising and/or pain at the site where the needle was injected. Your provider may advise you to avoid lifting heavy objects for 24 hours after your blood draw.
Results and follow-up actions
What do the results of a blood oxygen level test mean?
Blood test reports, including blood oxygen level test reports, usually provide the following information:
- The name of a blood test or what is measured in the blood.
- The number or measurement of your blood test results.
- Normal measurement range for this test.
- Information that indicates whether your results are normal or abnormal, high or low.
If your blood test results for blood oxygen levels are abnormal, it may mean that you:
- Not getting enough oxygen.
- Not enough carbon dioxide is eliminated.
- Blood pH imbalance (too acidic or too alkaline).
Blood oxygen level tests cannot diagnose specific conditions. If your results are abnormal, your healthcare provider will have you have more tests to confirm or rule out the diagnosis.
pulse oximeter
A pulse oximeter is a non-invasive device that estimates the amount of oxygen in your blood. It measures how much light is reflected by a gas by sending infrared light into capillaries in your fingers, toes or earlobes.
The reading indicates the percentage of saturation your blood has, called the SpO2 level. This test has a margin of error of 2%. This means the reading may be 2% higher or lower than your actual blood oxygen level.
This test may not be very accurate, but it's easy for doctors to perform. Therefore, doctors rely on it for quick readings.
Factors such as dark nail polish or cold extremities can cause pulse readings to be lower than normal. Your doctor may remove any polish from your nails before using the machine or if your readings are unusually low.
Since pulse oximeters are non-invasive, you can perform this test yourself. You can buy it at most health product stores or online. Talk to your doctor before using a home device so you know how to interpret the results.
Where should your blood oxygen levels drop?
Normal: Normal ABG oxygen levels in healthy lungs are between 80 and 100 millimeters of mercury (mm Hg). If the Pulse Ox measures your blood oxygen level (SpO2), a normal reading is usually between 95% and 100%.
However, in COPD or other lung diseases, these ranges may not apply. Your doctor can tell you what is normal for your specific situation. For example, patients with severe COPD maintain pulse oximetry (SpO2) between 88% and 92%.
Lower than normal: Blood oxygen levels lower than normal are called hypoxemia. Hypoxemia is often a cause for concern. The lower the oxygen level, the more severe the hypoxemia. This can lead to complications in body tissues and organs.
Generally, a PaO2 reading below 80 mmHg or a pulse oxygen (SpO2) below 95% is considered low. It's important to know what's normal for you, especially if you have chronic lung disease.
Your doctor can provide advice on the range of oxygen levels you can tolerate.
Higher than normal: If your breathing isn't helped, it's difficult for your oxygen levels to get too high. In most cases, people who use supplemental oxygen will experience high oxygen levels. This can be detected on the ABG.
What happens if your oxygen levels are too low
This includes:
- Shortness of breath
- chest pain
- Puzzled
- Headache
- Heartbeat
If your blood oxygen levels remain low, you may develop symptoms of cyanosis. The condition is marked by bluish discoloration of the nail beds, skin, and mucous membranes.
Cyanosis is considered an emergency. If you develop symptoms, seek medical attention immediately. Cyanosis can lead to respiratory failure, which can be life-threatening.
What causes low blood oxygen levels
- COPD, including chronic bronchitis and emphysema
- acute respiratory distress syndrome
- asthma
- Collapse of lung
- anemia
- congenital heart defects
- heart disease
- pulmonary embolism
These conditions may prevent your lungs from adequately taking in oxygenated air and exhaling carbon dioxide. Likewise, blood disorders and circulatory problems may prevent the blood from absorbing oxygen and carrying it throughout the body.
Any of these problems or disorders may cause oxygen saturation levels to drop. As your oxygen levels drop, you may begin to experience symptoms of hypoxemia.
People who smoke may have inaccurate readings. Smoking causes carbon monoxide to build up in your blood. Pulse cows can't tell the difference between this other type of gas and oxygen.
If you smoke and need to know your blood oxygen levels, an ABG may be the only way to get an accurate reading.
How to increase blood oxygen levels?
There are some ways to naturally increase the amount of oxygen in your blood, including:
- Breathe fresh air: Opening a window or taking a walk outside can increase the amount of oxygen your body takes in, thereby improving overall blood oxygen levels.
- Quit smoking: Your circulation may improve significantly in just two to three weeks after quitting smoking. After one to nine months, your breathing difficulty should lessen. Both of these aspects contribute to your body's ability to absorb more oxygen.
- Practice breathing exercises: Simple breathing exercises, such as pursed-lip breathing and deep abdominal breathing, can open your airways and increase the amount of oxygen in your blood.
You can use a pulse oximeter at home to check your blood oxygen levels to see if these natural ways to increase your oxygen intake are right for you.
However, it's important to note that if you have an underlying condition, especially a serious illness like pneumonia or carbon monoxide poisoning, these natural treatments may not be enough to increase your blood oxygen to acceptable levels.
If you develop signs of hypoxemia, get to the nearest hospital as soon as possible.
How to adjust blood oxygen levels
Home supplemental oxygen is considered a medication and must be prescribed by your doctor. It is important to follow your doctor's specific recommendations on how to use home oxygen to avoid complications.
Are low blood oxygen levels a sign of COVID-19?
COVID-19 affects people in different ways. Infected people experience a wide range of symptoms—from mild symptoms to severe illness. Some, but not all, people infected with COVID-19 develop low blood oxygen levels. If you have other symptoms, having normal blood oxygen levels does not mean you do not have COVID-19. Likewise, you may have low blood oxygen levels but not have COVID-19.
The only way to know for sure if you have COVID-19 is to get tested. While a home pulse oximeter can be helpful in some situations, it has limitations and can only show a small part of your health. Do not rely on an oximeter to confirm a COVID-19 diagnosis.
