Of the many fluids that play an important role in the human body, none compare to the fluid that is most abundant: blood.
As a vital substance that circulates throughout the entire body, blood serves three primary functions that all contribute to personal health: transportation, protection, and regulation. Yet of the many roles that blood can fill, perhaps it’s most important role is to transport oxygen to your cells while removing carbon dioxide, which is considered waste, to be released through the lungs upon exhale.
Maintaining those oxygen levels within the blood is no easy task. If low blood oxygen levels are present, problems can arise that spell impending health complications or even death.
High blood oxygen levels, on the other hand, are rare and often only occur when using supplemental oxygen. A harmful outcome that may transpire as a result of elevated blood oxygen levels (hyperoxia) is central nervous system toxicity — a condition in which seizures, disorientation, respiratory problems, and even death can occur.
While most children and healthy adults don’t need to monitor their blood oxygen level, those with chronic health conditions such as asthma, chronic obstructive pulmonary disease (COPD), and heart disease must do so on a regular basis.
Here we’ll break down the basics of blood oxygen levels, discuss how they’re measured, and give you a better understanding of the benefits of knowing your blood oxygen saturation levels.
What Is the Blood Oxygen Level?
Blood is composed of three primary ingredients that all contribute to its various responsibilities throughout the body. These three ingredients include a liquid substance referred to as plasma, and solids referred to as white blood cells and red blood cells.
Plasma is the most abundant substance in our blood (over 50% of blood is composed of plasma), which is made up of water, salts, and proteins. White blood cells are the cells of the immune system that protect the body against infection and disease. And red blood cells are the cells that carry oxygen throughout the body.
Given this information, blood oxygen level is simply a measure of how much oxygen is being carried by red blood cells in the body. The body will closely monitor blood oxygen levels to keep them within a specific range, ensuring that every single cell receives the oxygen it requires to function properly. This information is measured in millimeters of mercury, or mm Hg for short.
Now that we know what our blood oxygen level is, let’s discuss how it’s properly measured with the technology we have available today.
How Is Blood Oxygen Level Measured?
Of the two different ways that we can measure and monitor blood oxygen levels, the most efficient way is by an arterial blood gas, or ABG for short. To perform this test, a certified phlebotomist or licensed practitioner takes a blood sample from an artery in the body (often times the radial artery in the wrist) because unlike veins, which carry deoxygenated blood, arteries only carry oxygenated blood to cells.
The sample of blood acquired by the healthcare provider undergoes processing to determine levels of oxygen and carbon dioxide in the body. Though this process is efficient and accurate, it is also invasive and potentially painful, making it a less common choice compared to using a pulse oximeter.
A pulse oximeter, or pulse ox, is a small device that attaches to the fingertip and sends a beam of infrared light into the capillaries beneath the skin. From there, it measures how much light is reflected off the gases in the blood and provides a reading that accurately estimates what percentage of the blood is saturated with oxygen.
This measurement is often referred to simply as SpO2. While using pulse oximetry is slightly less accurate, it is extremely easy and non-invasive, making it the go-to measurement option amongst medical institutions around the world.
Unlike measuring ABG through a major artery, a pulse oximeter can be attached to the fingertip, toe, or earlobe with ease. Such equipment is often for sale through local pharmacy chain stores, so patients can even monitor their blood oxygen level at home. And while research once suggested that nail polish or acrylic nails could affect a pulse oximeter reading, new research now suggests otherwise.
High, Normal, and Low Blood Oxygen Levels
A measurement of oxygen levels in the blood is called oxygen saturation. Use the guidelines below to help understand what an oxygen saturation reading might mean.
High Blood Oxygen Levels
It is uncommon for oxygen saturation levels to be high if breathing is unassisted. That being said, supplemental oxygen may be required to heighten oxygen levels or bring them back to normal under certain conditions.
For instance, mountaineers who experience high altitudes may not receive enough oxygen from the surrounding air (this is because oxygen concentration levels in the atmosphere decrease as altitude increases). Alternatively, medical conditions may impair the amount of oxygen one can absorb into the blood.
In both cases, supplemental oxygen may be utilized to maintain healthy oxygen levels in the blood, and that supplemental oxygen can lead to high blood oxygen levels. As we mentioned above, excessive and consistent high levels of oxygen in the blood may lead to complications as a result of oxygen poisoning.
Normal Blood Oxygen Levels
Normal blood oxygen levels will fall between 80 and 100 mm Hg (millimeters of Mercury). And if a pulse oximeter is used to measure blood oxygen levels, a normal reading will fall between 95-100% saturation.
Low Blood Oxygen Levels
A reading below 80 mm Hg or 95% saturation is considered low, and we refer to this abnormally low concentration of oxygen in the blood as hypoxemia. Such low levels may be the result of a lung disease such as severe COPD that inhibits oxygen flow, or it could indicate there is carbon monoxide in the air, which the body will mistakenly use to replace oxygen.
To determine what factors are causing low blood oxygen levels, speak to a healthcare provider. Low blood oxygen levels can be an indication of serious complications within the body, and should therefore be addressed as soon as possible after detection.
Symptoms of Low Blood Oxygen Levels
Many symptoms may arise as a result of low oxygen levels in the blood. These include:
- Shortness of breath
- Chest pain
- Increased heart rate during simple activities or during sleep
- Visual disorders
- Lack of coordination
- Increased pulse rate
- Low blood pressure
Causes of Low Blood Oxygen Levels
Hypoxemia, or low oxygen blood levels, may be caused by the following primary complications. Additionally, medical conditions or environmental factors can contribute to the primary causes listed below.
- A low level of oxygen concentration in the air like you would experience at high altitude
- Poor lung conditions that cause a failure to inhale fully and send oxygen to cells and tissues, frequently caused by pneumonia, COPD, acute respiratory distress syndrome (ARDS), or sleep apnea
- Inability of the circulatory system to send blood through the lungs where it can collect oxygen, frequently associated with anemia, heart disease, certain medications
Treatment for Low Blood Oxygen
Treatment for low oxygen levels involves receiving supplemental oxygen to maintain normal oxygen levels. This form of intervention can be performed at home and is referred to as home oxygen therapy, or HOT for short.
Home supplemental oxygen is considered a medication and must, therefore, be prescribed by a doctor. As always, be sure to follow medical advice and consult a medical professional before utilizing any treatment options.
Additionally, lifestyle changes may positively benefit oxygen levels if levels happen to be low. For instance, consistent exercise and a healthy diet play an integral role in combating heart disease, which in-turn affects oxygen saturation levels in the body.
Monitoring Your Blood Oxygen Levels
While most people don’t need to monitor their blood oxygen saturation levels, those with health problems that cause low states of oxygen saturation would be wise to check their levels consistently. Doing so only requires a pulse oximeter, which can often be purchased at the nearest drug store.
Combating low oxygen levels through lifestyle changes, like adopting a healthier diet, starting a new exercise routine, or understanding your sleep habits can take to improve quality of life. When the lungs are happy and oxygen can circulate throughout the body, countless health benefits are in store.