Hypoxia and Hypoxemia

Have you ever experienced a situation where you suddenly become light-headed and find it difficult to breathe? Well, what you may be experiencing can either be hypoxia or hypoxemia. Hypoxia is a health condition in which the tissues and organs of the body, such as the brain as well as other vital organs don’t get oxygen.

Hypoxemia, on the other hand, is a condition where the bloodstream doesn’t get enough oxygen. Sometimes, a doctor can diagnose a patient of having hypoxemia when the saturation levels of the patient are very low.

Hypoxia can pose a dangerous threat to the body of a patient as it can cause severe damages to vital organs of the body and may drive the patient into a medical condition known as multiple organ failure (which occurs when several of the body’s vital organs stop functioning normally) if it isn’t treated on time.

Although these conditions look somewhat similar, however, they do not mean the same thing. Hypoxemia is a medical condition that occurs when the Red blood cells become deprived of oxygen. Hypoxemia can lead to hypoxia.

Generally, the normal oxygen levels range between 75-100mmhg. Anything above or below that poses a problem to the body. Once the oxygen in the blood drops to 60mmhg or less, hypoxemia will begin to occur, and the patient will need the use of supplemental oxygen.

Typically, the air that enters the lungs is a mixture of gasses and oxygen. This air travels through the respiratory tract and enters into the lungs. The lungs will then collect the oxygenated part of the air and attach it to the Red blood cells that was sent to the lungs through the pulmonary artery.

The now oxygenated red blood cells will then carry oxygen to the tissues of the body. When the oxygenated red blood cells get to the tissue, the tissues will collect the oxygen and make use of it and in exchange for the oxygen, give carbon dioxide back to the red blood cells so that they can carry it to the lungs where it can be expelled via the respiratory tract and the nose.

However, if there is a problem with the lungs or there is malfunctioning with the respiratory tract that makes it difficult for air to get into the lungs or for it to go out of the lungs; or if there is a medical condition that causes the level of oxygen in the blood to decrease, it will result in hypoxemia.


The causes of both hypoxia and hypoxemia are similar. Since hypoxia commonly leads to hypoxemia, we can easily conclude that the causes of hypoxia can lead to hypoxemia as well.

The common causes of hypoxia include:

1. Severe asthma attack

When a patient has a severe asthma attack or a flare can easily result in hypoxia. This is a common problem between children and adults. When a patient has an episode of an asthma attack, the respiratory tract becomes narrow, thereby preventing the free flow of air into the lungs.

If, at this point, the patient decides to cough, it worsens the condition of the patient as coughing repeatedly tightens the airways and as such restricting air from entering the lungs.

2. Sleep Apnea

Although some doctors claim that sleep apnea doesn’t cause hypoxia, however, some research reports show that there may be a link between sleep apnea and hypoxia. Sleep Apnea, on its own, won’t cause hypoxia; however, when it becomes quite severe, it may result in hypoxia.

On the other hand, recent research has shown that hypoxemia can be caused by sleep apnea. In the night when a person is struggling to deal with sleep Apnea, at that moment, the air isn’t entering the lungs, and as a result, the oxygen in the patient’s body declines.

Although the resulting oxygen loss is temporary, however, the longer the person sleeps, the longer the body parts are deprived of oxygen.

However, when the person wakes up from his/her sleep, the blockages in the airways are no longer there, and as such, the person can breathe normally again.

3. Chemical poisoning

Chemical poisoning, which mostly occurs by inhalation, can result in hypoxia. Having to inhale harmful chemicals such as pesticides as well as other poisonous chemicals can cause hypoxia and invariable may cause hypoxemia.

If a person has gas poisoning, the person is also at risk of developing hypoxia and hypoxemia.

4. High altitudes

Do you know that the higher you go, the lower the amount of oxygen you will get? This is the reason why mountain climbers and hikers always carry oxygen along with them. High altitudes cause the low concentration of oxygen or the total absence of oxygen, which in turn causes hypoxia.

5. Lung problems

The lungs are what is responsible for the oxygenation of the Red blood cells in the body. Air passes through the nose into the respiratory tract down to the lungs.

Now, if there is a problem with the lungs or if there is any disease that causes the decrease of lung function, it can lead to the reduction of oxygen in the blood as well as the tissues of the body.

Certain lung diseases such as Chronic Obstructive Pulmonary Disease(COPD), Emphysema, Bronchitis, Lung Cancer, Pulmonary Edema, Pneumonia, Asthma, Pneumothorax, Nocturnal Hypoxemia, and other lung problems can lead to hypoxia.

6. Some medications

Certain Medications can cause the constriction of the airways and, as such, lead to a shortage of oxygen. Drugs like Fentanyl and some other narcotics can lead to the stoppage of breathing.

7. Underlying heart issues

The heart is responsible for pumping blood into the organs of the body, including the lungs. Hence, any problem that affects the heart will reduce the effectiveness of the pumping of blood, and as such, blood may not get into the organs, including the lungs.

Heart conditions, such as ventricular fibrillation, as well as severe bradycardia, can cause hypoxia.

8. Other underlying health conditions

Some health conditions can result in hypoxia. These conditions don’t affect the heart or the functionality of the lungs.

Some conditions such as Anaemia, which can sometimes be caused by the premature breaking down and destruction, an arterial blockage which is often caused by a clot can result in the partial or complete blockage of blood flow to the lungs causing hypoxia.

Hypoxemia in Newborns

When a baby is born pre-term(which means before the expected delivery date), then the baby may likely develop hypoxemia. This is because their lungs may not be fully developed at the time of their birth and, as such, can result in hypoxemia.

Also, hypoxemia can also result as a result of congenital heart diseases. In fact, most times, doctors check for congenital heart defects using the levels of oxygen measured from the newborn.

Types of Hypoxemia

There are so many types of hypoxemia. Hypoxemia is divided into types based on the method or mechanism through which the oxygen levels in the blood are reduced.

Using this classification, the types of hypoxemia include:

1. Ventilation/Perfusion Mismatch

Ventilation/Perfusion Mismatch is often known and referred to as the most common type of hypoxemia. This mismatch usually occurs when the ratio between ventilation and perfusion isn’t equal or within the normal range.

Ventilation is a medical term that is used when referring to the process in which oxygen is supplied to the lungs, while perfusion, on the other hand, simply refers to the amount of the blood provided to the lungs.

Ventilation and perfusion are often recorded in a ratio known as the V/Q ratio. Generally, in medicine, a small mismatch among these two variables is usually accepted.

However, once the margin between the two variables becomes very large, then it is an indication that the patient is experiencing hypoxemia.

There are two reasons why there can be a ventilation-perfusion mismatch, and they include

  • When the lungs gets enough or an increased oxygen supply (increased ventilation), however, there is a decrease in the amount of blood supplied to the lungs (decreased perfusion). Once this occurs, the patient will experience an increased V/Q ratio leading to hypoxemia.
  • When there is a sufficient amount of blood supplied to the lungs i.e., normal perfusion rate but the amount of the oxygen provided to the lungs is very low (decreased ventilation). This can cause a decreased V/Q ratio and, as such, cause hypoxemia.

2. Shunt hypoxemia

In an average, healthy human, deoxygenated blood from the body usually enters through the right side of the heart via the inferior and superior vena cava. It then moves to the lungs via the pulmonary artery.

The lungs then oxygenates the blood and send it through the pulmonary vein back to the left side of the heart, from where it enters the aorta and eventually distributed back to the body.

However, when there is a shunt problem, the blood doesn’t go back to the lungs for oxygenation.

Instead, deoxygenated blood will enter directly into the left portion of the heart into the aorta and subsequently into the other parts of the body. Once this occurs, the body cells will begin to lack oxygen and, as a result causing hypoxemia to occur.

3. Diffusion Impairment

The lungs are like a bag with so many portions. One of those portions is known as the alveoli sac. The alveoli sac serves as a diffusion system in the lungs. Generally, when blood enters the lungs, it passes through the alveoli.

There are several tiny vessels that are seen around the alveoli, and these blood vessels are known as capillaries.

Oxygen passes from the alveoli into the capillaries. Once there is a blockage or compression of these capillaries, or there is a problem with the alveoli sac, it will result in the inability of oxygen to diffuse into the capillaries and, as such, resulting in hypoxemia.

4. Low environmental oxygen

These kinds of hypoxemia are often as a result of high altitudes and environments with little oxygen. As one ascends in height, the person will experience a substantial decrease in the amount of oxygen gotten from that place.

Staying at a higher level and breathing simply causes you to breathe in more carbon dioxide and less oxygen.

This is why scientists usually advise people who are used to climbing rocks and mountains, mountain hikers, and so on always to have an artificial source of oxygen.


A person who has hypoxia or hypoxemia will have issues with the intake of oxygen. This will therefore lead to symptoms such as

  1. Wheezing
  2. Severe shortness of breath
  3. Headaches
  4. Coughing
  5. Slow heart rates
  6. Disorientation as well as feelings of confusion
  7. If lack of oxygen becomes severe, it can lead to the bluish coloration of the skin, the fingertips, the fingernails as well as the lips.
  8. Rapid beating of the heart

Hypoxia and hypoxemia can be considered as two life threatening conditions and if they aren’t properly treated can result into life long complications.

If you have the basic symptoms and you suspect hypoxia or hypoxemia, it is important for you to get to the clinic immediately for treatment.

Your doctor will place you on supplemental oxygen and measure the rate at which your body absorbs it. He or she will also run some tests to know what caused you to have hypoxia and also, to know whether or not, there has been any damages to any of your organs.


For your doctor to confirm if you indeed have hypoxia or hypoxemia, he or she will carry out physical examinations first, before going to run any other tests.

The physical examinations will help to show if your heart and your lungs are responding normally and also show if your skin has the right coloration.

After these, your doctor will run additional tests to show your oxygen levels. Some of these tests include:

1. Pulse Oximetry

This is done by using a sensor based machine to help measure the oxygen levels in your blood. The sensor is placed on your fingers and then the readings will begin.

2. Arterial blood gas Test

This is done by using a needle to draw out a blood sample from the artery. From this blood sample, it is possible to detect the amount of oxygen present in the blood.

3. Breathing tests

These tests are carried out by you breathing into a tumble or through a machine. This test measures the amount of oxygen intake and how your breathing is, as well as the amount of oxygen that is present within your lungs.


Hypoxia and hypoxemia is basically as a result of the reduction in the oxygen levels within the body, hence, the aim of this treatment is to increase your oxygen levels back to normal. Oxygen therapy is often used to treat hypoxia nd hypoxemia.

Oxygen therapy involves the use of an oxygen nose mask or the use of a tube that is clipped to your nose to help you receive oxygen. Also, if hypoxia or hypoxemia is as a result of your asthma, your doctor will likely try to change your asthma medications or to adjust them.

However, if it is as a result of pneumonia, your doctor will prescribe antibiotics to help clear your lungs and help you breathe better.