Understanding Oxygen saturation


Oxygen saturation, or” O2 saturation, ” indicates the amount of oxygen that travels through your body along with red blood cells. Normal oxygen saturation is usually 95% to 100% for most healthy adults.

Any level below this is worrisome and needs immediate medical attention, as it means your organs, tissues and cells do not receive the oxygen they need to function properly.

This article discusses several conditions that affect the amount of oxygen in your blood and the complications that can result from low oxygen saturation. He will also talk about measuring blood oxygen levels, as well as treatments for low levels.

Learn about Medications / Laura porter

How The Blood Is Oxygenated

Understanding how blood is oxygenated begins with alveoli. or airbags. There are millions of those microscopic air sacs in the lungs. They play an important role: they allow the exchange of oxygen and carbon dioxide molecules in and out of the bloodstream.

When oxygen molecules pass through the alveoli, they bind to hemoglobin – the substance in the blood.

As hemoglobin circulates, oxygen essentially stops and enters the body’s tissues. In doing so, hemoglobin extracts carbon dioxide from the tissues and transports it back to the alveoli so that the cycle can begin again.

The level of oxygen in your blood depends on several key factors:

  • How much oxygen you inhale
  • How well the alveoli exchange carbon dioxide for oxygen
  • How much hemoglobin is concentrated in red blood cells
  • How well hemoglobin attracts oxygen

Most of the time, hemoglobin contains enough oxygen to meet the body’s needs. But some diseases reduce their ability to bind to oxygen.

Each of your blood cells contains approximately 270 million molecules of hemoglobin. but any condition that limits your body’s ability to make red blood cells can lead to low hemoglobin levels, which limits the amount of oxygen that can saturate your blood.

Conditions Affecting Oxygen Saturation

Circulatory disorders, circulatory problems, and lung problems can prevent your body from absorbing or transporting enough oxygen. In turn, this can reduce your level of oxygen saturation in your blood.

Examples of conditions that can affect your oxygen saturation include:

  • Respiratory infections (e.g., colds, flu, COVID-19), as they can affect your breathing and therefore your oxygen consumption
  • Chronic obstructive disease lung (COPD): a group of chronic lung diseases that make breathing difficult.
  • Asthma– chronic lung disease that causes narrowing of the airways .
  • Pneumothorax: partial or total lung collapse
  • Anemia: lack of healthy red blood cells
  • Heart disease– a group of conditions that affect how the heart works .
  • Thromboembolism pulmonary artery: when a blood clot causes a blockage in the pulmonary artery
  • Congenital heart defects: structural heart disease that is present at birth .

Measuring Your Levels

Oxygen saturation is usually measured in one of two ways: arterial blood gas analysis (ABG or Sa02) and pulse oximetry (Sp02).

ABH is usually only performed in a hospital setting, while pulse oximetry is performed in a variety of healthcare settings, including your treating physician’s office.


The ABG value refers to the levels of oxygen and carbon dioxide in the blood that flows through your veins.

A nurse or lab assistant draws blood from an artery, such as radial artery on the wrist or femoral artery in the groin. The sample is analyzed immediately by the machine or in the laboratory.

An ABG value can give your doctor an idea of how effectively hemoglobin exchanges oxygen and carbon dioxide.


Similarly, pulse oximetry readings reflect the percentage of oxygen in arterial blood.

Unlike the ABG test, invasive pulsoksimetriya. The test uses a Sensor to Read the wavelengths reflected in the blood. This probe simply attaches to your finger, earlobe, or other place on your body. The results will appear on the screen in a matter of seconds.

People can monitor oxygen saturation levels with portable pulse oximetry devices; some watches even have this feature. You can buy a pulse oximetry device at your local pharmacy or online.

Oxygen Saturation Levels
Read ABG Level The Sat Result
Below Standard < 80 mmHg Art.  < 95%
Normal > 80 mmHgArt. 95% to 100%

Reduced Oxygen Saturation

Reducing oxygen saturation in the blood is called hypoxaemia. Possible causes of hypoxemia include:

  • Less oxygen in the air you breathe-for example, while flying in an airplane
  • Conditions that affect breathing, such as asthma and COPD
  • Conditions that affect oxygen absorption, such as pneumonia
  • Anemia causing lower hemoglobin level
  • Inhalation of another substance, such as carbon monoxide or cyanide, that binds more strongly to hemoglobin than to oxygen

Complications of low oxygen saturation

Low oxygen saturation in the blood can affect the concentration of oxygen in the body’s tissues, including organs and muscles. This condition is called hypoxia.

Your cells can adapt to a lack of oxygen when the deficiency is small. However, with great deficiencies, cell damage can occur followed by cell death.

Hypoxia is often caused by hypoxemia, but it can also occur when:

  • There are not enough red blood cells to carry oxygen to the tissues. Possible causes include heavy bleeding due to injury or sickle cell anemia.
  • There’s insufficient blood flow. For example, a stroke occurs when there is low blood flow to an area of the brain, while a heart attack occurs when there is low blood flow to the heart muscles. Both lead to cell and tissue death.
  • Tissues require even more oxygenated blood than can be given. Serious infections that lead to sepsis. they can lead to hypoxemia and eventually organ failure.


Generally speaking, an oxygen saturation level below 95% is considered abnormal, and anything below 90% is an emergency.

When this happens, it is necessary oxygen therapy – sometimes it’s urgent. The brain is the organ most susceptible to hypoxia, and brain cells can begin to die within five minutes of lack of oxygen. If hypoxia lasts longer, coma, seizures, and brain death may occur.

It is very important to determine the cause of the low oxygen saturation to eliminate the problem. In chronic diseases such as COPD and asthma, the main cause is often low airflow in the lungs and alveoli. In addition to oxygen therapy, steroids or bronchodilators (rescue inhalers).

In diseases of the circulatory system, such as heart disease, insufficient blood flow can reduce the oxygen supply. Medicines that improve heart function, such as beta blockers in heart failure or prescriptions for treating cardiac arrhythmias. it can help improve oxygen saturation.

In anemia, the blood supply to the tissues is reduced because healthy red blood cells with hemoglobin are not enough to carry oxygen. Sometimes, red blood cell transfusion is needed to increase healthy red blood cell levels.


For people with chronic diseases that affect their lungs, blood, or circulation, it is important to regularly monitor oxygen saturation. Keep in mind that O2 sat levels below 95% tend to be abnormal and require urgent medical attention. If not treated in a timely manner, the drop in oxygen saturation will cause cell and tissue death.

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