Everything you Need to Know About Blood Oxygen Levels

Blood oxygen levels indicate how much oxygen is circulating in the blood at a given time. So, how does oxygen get from our lungs to the rest of the body? When we breathe, air enters the lungs, and available oxygen binds to circulating red blood cells which carry it throughout the body. Oxygen is then delivered to the organs, tissues, and cells and used as fuel to perform their intended function. After the tissue uses the available oxygen, it gets converted into carbon dioxide. The red blood cells then attach to carbon dioxide molecules and carry them back to the lungs to be exhaled. A few factors are necessary to supply the tissues with an adequate amount of oxygen and enable this process to function appropriately are:

  1. Having enough available oxygen in the air.
  2. The lungs’ ability to operate efficiently by supplying circulating red blood cells with enough oxygen and riding the body of carbon dioxide.
  3. Red blood cells’ ability to attach and carry oxygen.
  4. The circulatory system’s ability to circulate blood throughout the body.

Having enough oxygen available to the organs is essential for our bodies to work correctly. If there is not enough oxygen being delivered to our organs, due to a discrepancy in any of the factors listed above, it can lead to symptoms such as shortness of breath, dizziness, confusion, headache, and fast heartbeat. Having low levels of oxygen in the blood is defined as hypoxemia. Some conditions that can lead to hypoxemia include COPD, asthma, cystic fibrosis, heart diseases, high altitude, sleep apnea, and anemia. If hypoxemia is left untreated, it can lead to hypoxia. Hypoxia is a condition in which the organs are depleted of oxygen and cannot perform their normal functions, which can cause damage to vital organs, particularly the heart and brain.

How is Blood Oxygen Level Measured?

There are two ways to test the oxygenation of the blood. The first, most accurate test is a blood draw called an arterial blood gas test or ABG. Blood is taken from the radial artery in the wrist and sent to a lab and analyzed. The results of this test disclose the pH, oxygen content, and content of other gases in the blood. Arterial blood gas test results are given in millimeters of mercury (mmHg) and are very accurate, but because blood is taken from an artery rather than a vein, it can be painful.

The second way to measure blood oxygen level is with a pulse oximeter. A pulse oximeter is a device that is most commonly placed on a finger but can also clip onto a toe or earlobe and measures the percentage of blood saturated with oxygen, or SpO2. The device emits an infrared light into the capillaries of the finger and measures how much light reflects off the gases in the blood. The reading is given as a percentage. This test is slightly less accurate, with a 2% margin of error, but it is quick, non-invasive, and easy to perform by either you or your physician.

What is a Normal Oxygen Level?

According to Mayo Clinic, ABG readings between 75 and 100 mmHg and SpO2 readings between 95-100% are considered normal. Anything under 75 mmHg and 90% is low, and values below 60 mmHg indicate the need for immediate medical treatment. Although these are the guidelines, it is important to consult with your physician to determine your body’s normal oxygen levels. It is vital that anyone with a chronic health condition, such as sleep apnea or COPD, monitor their blood oxygen levels regularly to ensure their current treatments are sufficient or if they need to be adjusted.

Increasing Oxygenation of the Blood

Typically, the body regulates blood oxygen levels on its own, and even healthy individuals can occasionally experience low oxygen levels caused by intense exercise or even a trip to the mountains. In these cases, the body will adjust, and intervention is not usually needed. However, if hypoxemia is severe due to chronic illnesses, such as heart or lung diseases, supplemental oxygen therapy is necessary. Oxygen is supplied through a nasal cannula or a mask worn over the nose and mouth. In addition to treating hypoxemia, it is imperative to identify any underlying conditions that could be causing it to find the best course of treatment.