Importance of Biochemistry

What do oxygen levels in blood express?

Oxygen levels in blood?

What do oxygen levels in the blood express?

The levels of oxygen in the blood show the amount of oxygen carried by the red blood cells.

As the body regulates the levels of oxygen in the blood accurately, and it is necessary to maintain an accurate balance of the blood saturated with oxygen for health in general.

Most children and adults do not need to check blood oxygen levels, and a doctor does not usually order this test, unless there are signs of a problem such as difficulty breathing and chest pain.

But people with chronic diseases should check their oxygen levels, such as those with heart disease, asthma and COPD.

In these cases, the doctor uses the levels of oxygen in the blood to evaluate whether or not treatment is effective.

How are blood oxygen levels measured?

It is measured in two ways:

Arterial blood gas examination:

It is a blood test that measures oxygen levels in the blood, and detects levels of other gases in the blood, in addition to measuring the acidity of the blood, which is an accurate, non-invasive test.

For this procedure, the doctor draws blood from an artery, not from a vein. Arteries, unlike veins, have a palpable pulse, and blood drawn from arteries is oxygenated blood, unlike venous blood.

The artery in the wrist is used because it is easier to palpate than other areas of the body, however it may be difficult to draw blood from this area compared to a vein near the elbow.

Because the arteries are deeper than the veins, the patient may be upset because the wrist is a sensitive area.

The normal oxygen level in the blood - the amount of oxygen carried by the red blood cells - an accurate balanced ratio of the blood saturated with oxygen - the venous blood - the oxygen levels

Pulse oximeter:

It is a non-invasive device that assesses the amount of oxygen in the blood, by infrared radiation that it sends to the capillaries in the finger, toe or earlobes, and measures the amount of rays reflected from the gases.

The reading indicates the percentage of blood oxygen saturation (SpO2), and this scale has an error range of 2%, meaning that the result may be 2% higher than the real value or less than it.

This scale may be less accurate, but clinicians are much easier to perform, so they rely on it for rapid readings.

Some things may affect the reading of the scale – such as dark polish or cold extremities – and make it give a reading below the true value,

And the doctor may remove the nail polish if he gets an unreasonably low reading.

You can do this measurement on your own because it is non-invasive, and you can buy a meter from anywhere that provides medical instruments.

But you should consult a doctor before that. To understand the meaning of the score given by the scale.

What are the normal values ​​of blood oxygen?

The following values ​​give an idea of ​​the meaning of the blood oxygen level test result:

Normal values:

The normal blood gas values ​​for healthy lungs are between 80-100 mmHg, and when using a pulse oximeter, the normal reading is between 95-100%.

However, these values ​​may not apply to some cases, such as lung diseases and chronic obstructive pulmonary disease, and doctors inform the patient of the appropriate values ​​for each case.

In severe cases of COPD, for example, pulse oximeter values ​​between 88-92% are common.

Lower than normal values:

This condition is called hypoxia, and it is a often worrying condition, and the lower the blood oxygen levels, the worse the hypoxia state, as it may lead to complications in the organs and body tissues.

Blood oxygen levels in blood gases below 80 mmHg are low, as are pulse oximeter values ​​below 95%.

It is important to know the normal values ​​for each individual person, especially those with chronic diseases, as the doctor gives an idea of ​​the normal areas for each case.

Higher than normal values:

It is difficult for the oxygenation values ​​to be higher than normal values ​​when breathing normally, as most cases of these values ​​rise when using oxygen with assistive devices, and these values ​​can be detected by examining the blood gases.

What happens when oxygen levels are low?

Symptoms that may appear when blood oxygenation values ​​are outside the normal range:

  •  breathing difficulties.
  •  Chest pain.
  •  confusion.
  •  a headache.
  •  Acceleration in the heart.

Symptoms of cyanosis may appear when low levels of blood oxygenation persist.

The hallmark of cyanosis is blueness of the roots of the fingernails, skin, and mucous membranes.

Which is an emergency condition that requires immediate medical attention when it occurs because it may lead to respiratory failure, which is a life-threatening condition.

How can blood oxygen levels be adjusted?

The patient may need to boost the level of oxygen saturation if his oxygen levels are too low, and this is done by assisted oxygenation devices.

Home reserve oxygen is a treatment your doctor may prescribe. It is important to follow your doctor’s instructions on how to use it to avoid complications.

What causes low blood oxygen levels?

Conditions that negatively affect blood oxygen levels include:

  • Chronic obstructive pulmonary conditions such as chronic bronchitis and emphysema (emphysema).
  •  Acute respiratory distress syndrome
  •  asthma.
  •  Pulmonary collapse.
  •  Anemia.
  • Congenital heart defects.
  •  Heart disease.
  •  Pulmonary embolus.

These conditions prevent the lungs from breathing sufficient air that contains oxygen and exhaling carbon dioxide.

Also, blood disorders and diseases of the circulatory system prevent blood from extracting oxygen and transporting it to the body.

Any of the previous conditions can cause oxygen levels to drop, and symptoms begin to appear when levels of blood oxygenation decrease.

The pulse oximeter may give high imprecise values ​​in smokers, if their blood carbon monoxide levels are high, and this scale does not differentiate between oxygen and other gases.

Therefore, the blood gas test gives accurate values ​​of blood oxygenation in smokers.


Most people do not need to check their oxygen levels periodically, as it is only required for those with health problems that cause low levels.

And even in most of these cases a non-invasive pulse oximeter is useful as a blood gas test.

With a slight error in the pulse oximeter, it is accurate most of the time, and if a more accurate examination of blood oxygen levels is required, a blood gas test can be used.

Read more:

Normal blood oxygen level?

Also read it:

How to combat high blood pressure?

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button