Oxygen Saturation

Blood Oxygen Saturation

What Is Blood Oxygen Saturation?:

Oxygen saturation refers to the amount of oxygen that’s in your bloodstream. The body requires a specific amount of oxygen in your blood to function properly. The normal range of oxygen saturation for adults is 94 to 99 percent. Anyone with an oxygen saturation level below 90 percent will likely require supplemental oxygen, which is prescribed by your primary care doctor or pulmonologist.


On a deeper level, oxygen saturation refers to the degree to which the hemoglobin in your red blood cells has bonded with oxygen molecules. Oxygen in the bloodstream comes from your lungs and is taken in when you inhale.

What Is Blood Normal Range of Blood Oxygen Saturation?:

The normal oxygen saturation level is 97–100% .

Older adults typically have lower oxygen saturation levels than younger adults. For example, someone older than 70 years of age may have an oxygen saturation level of about 95%, which is an acceptable level.


It is important to note that the oxygen saturation level varies considerably based on a person’s state of health. Thus, it is important to understand both baseline readings and underlying physiology associated with certain conditions to interpret oxygen saturation levels and changes in these levels.

What happpen if Blood Oxygen Saturation is Low?:


When your blood oxygen level goes outside the typical range, you may begin experiencing symptoms.

This includes:
  • shortness of breath
  • chest pain
  • confusion
  • headache
  • rapid heartbeat

If you continue to have low blood oxygen levels, you may show symptoms of cyanosis. The hallmark sign of this condition is a blue discoloration of your nail beds, skin, and mucus membranes.Cyanosis is considered an emergency. If you’re experiencing symptoms, you should seek immediate medical attention. Cyanosis can lead to respiratory failure, which can be life-threatening.


How to Measure Blood Oxygen Saturation: 

ABG Test Vs Pulse Oximeter

ABG Test:

An ABG test measures the amount of oxygen and carbon dioxide present in the bloodstream and can be used to help diagnose COPD. It can also determine the acidity, or pH, of your blood. When you inhale, oxygen flows into the blood and is carried via red blood cells throughout your body. Carbon dioxide, on the other hand, flows out of the blood and back into the lungs. An ABG test can reveal how effectively your lungs bring oxygen into the bloodstream and remove carbon dioxide from the bloodstream.


However ABG test is test that involves using a needle which  carries some risks, including bleeding, infection, and bruising. You might have some soreness where the needle went in.

Pulse Oximeter:

A pulse oximeter clips onto your finger and indirectly measures oxygen saturation. It shines light beams into the blood circulating in your capillaries, which reflect the amount of oxygen in the blood. Pulse oximeter readings are expressed as a percentage. As stated above, a reading of 94 to 99 percent or higher indicates normal oxygen saturation, and anything below 90 percent is considered to be low blood oxygen, also known as hypoxemia.


Howvever, pulse oximetry have disadvantage that movement artifact can be significant and the modality may provide an erroneous reading when pulsatile flow is inadequate (ie, shock with poor perfusion) or in the presence of anemia.

What cause Blood Oxygen Saturation Low?:


A variety of conditions and circumstances can interfere with the body’s ability to deliver normal levels of oxygen to the blood. Some of the most common causes of hypoxemia include:

  • Heart conditions, including heart defects
  • Lung conditions such as asthma, emphysema, and bronchitis
  • Locations of high altitudes, where oxygen in the air is lower
  • Strong pain medications or other problems that slow breathing
  • Sleep apnea (impaired breathing during sleep)
  • Inflammation or scarring of the lung tissue (as in pulmonary fibrosis)