Blood oxygen levels in the body indicate how much oxygen the red blood cells carry. A human body closely monitors normal blood oxygen levels in general. Maintaining normal oxygen saturation levels is crucial for health. In most cases, doctors do not even check the low blood oxygen levels using advanced instruments unless the patient shows problems like chest pain and breathing difficulties. So healthy people do not need to be conscious of normal blood oxygen levels. However, it is vital for people with serious illnesses to keep an eye on blood oxygen levels. This includes problems like asthma, chronic obstructive pulmonary disease (COPD), and heart diseases.
Normal blood oxygen levels mean the body distributes the oxygen all over the body sufficiently. The transition of oxygen from lungs to cells and tissues is seamless. Any obstruction in this process can create a health problem, especially for people already dealing with a disease. This is why doctors adjust the treatment according to blood oxygen levels. Thus it is vital to monitor blood oxygen levels and symptoms of low blood oxygen levels.
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How Do We Measure Blood Oxygen Level?
As we know, blood oxygen levels are an indicator of how much oxygen our arteries carry. An ABG test is generally done by doctors, which draws blood from the body from the artery. The blood oxygen levels are measured from this sample. A pulse oximeter is another way how one can check the blood oxygen levels even at home. Let us now understand about both of these ways in a bit detail-
Arterial Blood Gas (ABG) Testing-
An arterial gas test not only measures the blood oxygen levels in the body but also detects the level of other gases present in the blood. It also checks the pH levels, i.e., the acid and base level of the blood. The blood is then put in an ABG machine (blood gas analyzer) that shows the blood oxygen levels in the partial pressure of oxygen (PaO2).
High blood oxygen levels or Hyperoxemia are usually detected using ABG testing, and the blood oxygen levels show them above 120 mmHg. Normal arterial oxygen pressure (PaO2) or normal blood oxygen levels, measured using the arterial blood gas (ABG) test, are approximately between 75 to 100 millimeters of mercury (75-100 mmHg). When the oxygen level goes below 75 mm Hg, then it is a condition of low blood oxygen level or Hypoxemia. Blood oxygen levels under 60 mm Hg are considered low and indicate the need for supplemental oxygen. In such cases of low blood oxygen levels, supplementary oxygen through an oxygen cylinder connected with an oxygen mask or nose is provided to the patient.
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A pulse oximeter, unlike the ABG testing, is a non-invasive testing device. A pulse oximeter is a small device that estimates the blood oxygen level in the body. Oximeter does so by signaling infrared light into capillaries of the finger, toe, or even earlobe. It then measures the amount much light reflected by the gases as well. The reading of the pulse oximeter shows the percentage amount of oxygen saturated in the blood. This is called the SpO2 level. The normal blood oxygen levels in a pulse oximeter generally range from 95% to 100%. Below 90%, the blood oxygen levels are considered low (hypoxemia).
This device has a 2 percent of error window. Meaning, the oximeter can show 2 percent more or less reading from the actual blood oxygen levels. Thus this testing is not as accurate as the ABG testing, but it is convenient and shows fast results. Moreover, the readings of blood oxygen levels through an oximeter are usually reliable for the doctors. Some exceptions to normal oximeter readings can be nail polish on patients’ nails or extreme weather conditions under which the blood oxygen levels are not properly detected.
In situations like the COVID 19 pandemic, the blood oxygen levels are affected when the virus attacks the breathing system. A pulse oximeter is an easy to use and fast device. This is why most people have oximeters at their homes just to be on the safer side.
The Normal Blood Oxygen Levels-
The measurement of blood oxygen level in the body is called the oxygen saturation level. In medical terms, it is referred to as PaO2 in blood gas and O2 saturation/ SpO2 while using a pulse oximeter. Below are given some basic categories which can help you better understand the normal blood oxygen levels.
Blood Oxygen Levels Chart-
|Medical Condition||SpO2 Level||Need for Medical Assistance|
|Normal||95% and above||No medical assistance needed|
|COPD||88% – 92%||Respiratory monitoring required|
|Hypoxemia||85% – 94%||Monitor underlying respiratory problems. If COPD patient, oxygen therapy is needed.|
|Acute Hypoxemia||Below 85%||Supplemental oxygen is required urgently.|
|Lack of oxygen in the brain||80% – 85%||Supplemental oxygen is required urgently.|
|Cyanosis||65%||Supplemental oxygen with ventilation service is required urgently.|
Normal and Healthy Blood Oxygen Levels:
The normal ABG level of oxygen for healthy lungs ranges between 80 and 100 (mm Hg) of mercury. If the blood oxygen level (SpO2) is measured by oximeter, a normal reading is usually between 95 and 100 percent.
However, in conditions like COPD or lung disease, these ranges may not be considered normal. The doctor specifies the normal blood oxygen level for these medical conditions. For example, it is common for people with severe COPD or any lung disorder to keep their blood oxygen level or SpO2 between 88% to 92%.
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Low Blood Oxygen Level:
A below-normal or low blood oxygen level is called Hypoxemia. Hypoxemia is a medical condition that requires attention. The lower the blood oxygen level, the more severe the hypoxemia gets. It can even lead to complications in the tissues and organs.
Typically, the PaO2 reading below 80 mm or a pulse oximeter reading (SpO2) below 95% is regarded as low. Thus, it is vital to understand the normal blood oxygen levels, especially for people with a chronic lung condition. A doctor’s assistance is crucial in knowing what the normal blood oxygen levels for specific illnesses are.
If the low blood oxygen levels continue, the patient may even show symptoms of a condition called cyanosis. The typical symptom of this condition is a blue discoloration of nail beds and skin.
Cyanosis is an emergency medical condition. A person should seek immediate medical attention to address this problem. Cyanosis can even lead to obstruction of the normal functioning of body organs or respiratory failure.
High Blood Oxygen Levels:
This condition usually occurs with people who are given supplemental oxygen assistance. It is a rare condition and can be easily detected by ABG testing.
What Happens If The Blood Oxygen Levels Are Not Normal?
When the blood oxygen level is not normal, which is in most cases a low blood oxygen level, some typical symptoms are experienced-
- Shortness of breath or breathing difficulty.
- Chest pain
- Irregular heartbeat
- Nausea or vomiting
If the blood oxygen level is too low, an urgent boost to oxygen saturation is needed. Supplemental oxygen usually comes to the rescue. Home supplemental oxygen is also considered a medication, and many doctors prescribe it. Hence, it is vital to follow the doctor’s specific advice on using home oxygen to avoid complications. Furthermore, it is wise to adopt a healthy lifestyle by eating a balanced diet and doing regular exercise to maintain normal blood oxygen levels and prevent any underlying cause that can give rise to irregular blood oxygen levels.