What Is Hypoxemia?

By definition, hypoxemia means having an unusually low concentration of oxygen in your blood. Hypoxemia should not be confused with hypoxia, which is a deficiency of oxygen in your tissues, although the former can certainly lead to the latter if the condition is not addressed.

As most of you are likely aware, the relationship of blood and oxygen in our body is very important, and also quite complex. Our blood constantly flows around the body, delivering oxygen and other nutrients to the tissues and organ systems that need it most.  When the concentration of oxygen in the blood is too low, however, it results in a condition called hypoxemia. This is not something to be ignored or taken lightly, as it can be a sign of a more serious health problem, and may also cause a number of unwanted and worrying side effects.

What is Hypoxemia?

By definition, hypoxemia means having an unusually low concentration of oxygen in your blood. Hypoxemia should not be confused with hypoxia, which is a deficiency of oxygen in your tissues, although the former can certainly lead to the latter if the condition is not addressed. To assess for hypoxemia, the concentration of oxygen is measured in a sample of arterial blood, but a simpler method involves the use of a pulse oximeter on the tip of your finger, which can accurately measure the oxygen saturation of your blood. Normal levels for arterial blood concentration range from 75-100 mm Hg, while any figure under 65 can be deemed hypoxemic. The pulse oximeter measurement should range from 95-100% saturation.

but I get the job done meme

As you can guess, hypoxemia reflects some type of problem in either your circulatory or respiratory systems, and can have a number of different symptoms and causes.

Symptoms of Hypoxemia

Since hypoxemia is so closely related to oxygen levels and intake, some of the main symptoms of this condition affect your respiratory system. Shortness of breath – the feeling that one can’t quite take a deep enough breath – is the most common complaint from sufferers of hypoxemia. A heightened rate of breathing is another typical symptom, along with chronic breathing from the chest, rather than the diaphragm.

The dangerous part of this condition, of course, is that the body may compensate for it over long periods of time, preventing one from even knowing they are suffering. However, when the body is exposed to a high oxygen demand, e.g., during an intense workout, the shortness of breath may become more apparent. If you are suffering from chronic hypoxemia, it can result in strain to the heart, due to the imbalance between ventricles, and may also lead to pulmonary hypertension.

hypoxemia is sure to follow meme

Due to the low concentration of oxygen in the blood, other symptoms can include cyanosis (blue or purple mottling or discoloration on the extremities), poor sleep quality, headache, irritation, mental confusion, or exacerbated respiratory symptoms, such as coughing or wheezing. In the most serious cases of this condition, specifically in long-untreated chronic situations, hypoxemia can cause respiratory failure.

Causes of Hypoxemia

There are three elements that affect your blood oxygen concentration – the amount of air you’re breathing, your lungs’ ability to pass that oxygen into the blood, and your blood’s ability to carry that oxygen throughout the body. If any of these three factors are compromised, you are at a much higher risk for hypoxemia.

For example, if you suffer from asthma, or have a blocked airway, your ability to take in enough oxygen may be the culprit, whereas if you have a congenital heart disease, your heart may be unable to pump enough fully oxygenated blood around your circulatory system.

One of the tools used to measure and diagnose hypoxemia is called the Alveolar-arterial gradient (A-a gradient). This gradient represents the difference between the Alveolar and arterial concentrations of oxygen. Establishing this gradient will inform doctors where/when in the oxygenation process the problem is occurring.


Some cases of hypoxemia are caused by an inability to intake enough oxygen. This could be caused by being at a high altitude with a lower concentration of oxygen, suffocation, deep-sea diving or even the use of certain anesthetics. Furthermore, obstruction of the airways can lead to hypoxemia, which could be caused by sleep apnea or physical deformities of the chest. If there is a problem with your central nervous system and breathing center, your body simply may not be instructing you to breathe as often as is necessary.

I'm not always perfect.


Once the oxygen is taken into the lungs, it must be diffused into the blood, but this may not always happen, resulting in low-oxygen blood being pushed out into the blood stream. Our ability to diffuse oxygen through the alveolar membrane decreases as we age, but only minimally. This condition may also be caused by a disease, such as pulmonary fibrosis or chronic obstructive pulmonary disease (COPD). Intense levels of exercise could also cause a drop in the diffusion efficiency of oxygen into the blood. Shunting of various forms can also lead to low blood oxygen concentration, as the blood is diverted away from the alveoli, where it would receive oxygen.


If carbon dioxide is not removed from the bloodstream at the same rate as it is produced, it can cause oxygen concentrations to drop. Furthermore, during intense physical exercise, when the blood is pumping extremely hard, there is not time for complete gas diffusion at the alveoli, which can lead to depleted oxygen levels in the blood. There are also some capillaries in the lungs that are only used during intense physical activity to reduce venous pressure, but the blood that passes through those capillaries is typically not oxygenated. Over an extended period, this can cause hypoxemia.

Treatment for Hypoxemia

Increasing your oxygen intake is the most obvious way to relieve the symptoms of this condition, which is why inhalers and oxygen masks are often employed. Oral asthma medication is also recommended in some cases, or steroids to reduce potential inflammation in the lungs that could be affecting alveolar diffusion.

and also hypoxemia. meme

As explained above, however, there are many potential causes to this condition, including more serious health risks such as anemia, emphysema, pneumonia or a pulmonary edema. If the underlying cause of the condition is identified and treated, it is possible to eliminate the other symptoms of hypoxemia. Lifestyle changes, such as regular exercise and dietary alteration, may also improve the health of your circulatory and respiratory systems.

A Final Word

While some of the symptoms may seem mild and temporary, it is important to see a doctor if you suspect that your blood oxygen concentration is low. When left untreated, this condition can become very serious, and have a long-term, negative impact on your quality of life. You want to breathe freely and access all the life-giving oxygen you can, so speaking with a  professional about your occasional shortness of breath may be your first step towards a healthier, happier tomorrow!


  1. National Institutes Of Health (NIH) (Link 1)
  2. National Institutes Of Health (NIH) (Link 2)
  3. CU Denver
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About the Author:

John Staughton is a traveling writer, editor, publisher and photographer who earned his English and Integrative Biology degrees from the University of Illinois. He is the co-founder of a literary journal, Sheriff Nottingham, and the Content Director for Stain’d Arts, an arts nonprofit based in Denver. On a perpetual journey towards the idea of home, he uses words to educate, inspire, uplift and evolve.

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