Hypoxia

Hypoxia is when the tissues or organs in your body don’t have enough oxygen. When you breathe, you take oxygen into your lungs, where it travels through your airways. It goes into small sacs called alveoli deep in your lung. In small blood vessels that surround alveoli, blood picks up oxygen and carries it. Oxygen remains in your blood until it arrives at other tissues in the rest of your body.

You can think of oxygen as billions of passengers flying into your lung “airport.” They get picked up at the gate by red blood cell “taxis” and get on blood vessel “highways” to reach your tissues. As blood vessels drop off oxygen, they pick up carbon dioxide. This is a waste product that goes back to your lungs and leaves your body when you breathe out.

If not enough oxygen gets through at any place on the journey, it can lead to hypoxia. Airflow and blood flow are both important to the process. This is why lung disease and heart disease both increase your risk of hypoxia. Someone who experiences hypoxia is called hypoxic. This condition can happen suddenly or be a long-term problem.

What are the four types of hypoxia?

The four different types of hypoxia are hypoxemic, circulatory, anemic and histotoxic. They happen because you don’t have:

• Enough oxygen in the air you breathe in
• Healthy lung function to get oxygen to your alveoli or into your blood vessels
• Healthy heart and circulatory functions to get oxygen-rich blood to your tissues
• Enough red blood cells to deliver oxygen
• Tissue cells capable of using oxygen

Hypoxemic

Low amounts of oxygen in your blood (hypoxemia) can lead to hypoxemic hypoxia. It’s the most common cause of hypoxia. Hypoxemia can come from lung and heart diseases, heart defects present at birth, and medications or health conditions that slow your breathing. Traveling to a high altitude, where levels of oxygen are lower, can also cause hypoxemia.

Circulatory

Your blood can have plenty of oxygen, but not enough of it reaches your tissues if your heart doesn’t pump enough blood or there’s a blockage in a blood vessel. This is called circulatory hypoxia (also called stagnant hypoxia or ischemic hypoxia). Congestive heart failure, blood vessel diseases and blood clots can increase your risk of this type.

Anemic

Anemic hypoxia happens when you don’t have enough red blood cells to carry oxygen from your lungs to other tissues. You can become anemic if your body doesn’t make enough red blood cells or if it makes deformed or ineffective red blood cells.

Histotoxic

Histotoxic hypoxia happens when your cells aren’t able to use oxygen properly. In this case, you can have plenty of oxygen coming into your lungs and entering your blood. But when it arrives at your tissues, something keeps your cells from being able to use it. This can happen with cyanide poisoning.

Symptoms of hypoxia

Hypoxia symptoms vary depending on the severity, underlying cause and which parts of your body it affects. Some conditions may cause long-term (chronic) hypoxia with less severe symptoms. When your oxygen is low, you might feel like you can’t breathe or think properly. Some general hypoxia symptoms include:

• Restlessness
• Headache
• Confusion
• Anxiety
• Rapid heart rate (tachycardia)
• Rapid breathing (tachypnea)
• Difficulty breathing or shortness of breath (dyspnea)

Severe hypoxia can cause a slow heart rate (bradycardia), extreme restlessness and bluish skin (cyanosis).

Hypoxia to certain tissues or organs can have symptoms specific to that area. This is most commonly associated with blockage of blood flow (ischemia), like the chest pain that occurs with heart attacks.

Hypoxia causes

Any condition that reduces the amount of oxygen in your blood or restricts blood flow can cause hypoxia. It happens most often because of an underlying illness that affects blood flow or breathing. Conditions that can lead to hypoxia include:

• Anemia
• Asthma
• Bronchitis
• Chronic obstructive pulmonary disease (COPD)
• Congenital heart disease
• Congestive heart failure
• Emphysema
• Pneumonia
• Pneumothorax (air in the space around the lung or collapsed lung)
• Pulmonary edema (fluid on the lungs)
• Pulmonary embolism (blood clot in the lung)
• Pulmonary hypertension (high blood pressure in your pulmonary arteries)
• Pulmonary fibrosis (lung scarring)
• Sleep apnea

Risk factors

People living with heart or lung diseases like COPD, emphysema or asthma are at an increased risk for hypoxia. Some infections — like pneumonia, influenza and COVID-19 — can also increase your risk of becoming hypoxic.

How to lower your risk

The best way to reduce your risk of hypoxia is to manage any conditions that can lower your oxygen levels. If you live with a heart or lung problem, talk to your healthcare provider about your concerns and specific ways to lower your risk. These could include medications, inhalers, devices that assist breathing or supplemental oxygen, to name a few.

Be aware that certain medications and situations — like traveling to a higher altitude — might increase your risk of hypoxia. Ask your provider about any special precautions you need to take while traveling or changing medication.

If you have an underlying condition that led to — or could lead to — hypoxia, managing that condition is the best way to lower your risk of it happening again. Here are some tips:

• Don’t ignore new symptoms. Trust yourself if you feel something is off and contact your healthcare provider or go to the ER.
• Take care of yourself. If you have asthma, know your triggers and make sure you have a rescue inhaler if prescribed. Perform breathing exercises using an incentive spirometer and follow any other lung health recommendations from your provider.
• Quit smoking and using tobacco products. If you smoke, quitting can help increase lung function and prevent further damage to your lungs.
• Take any medication your healthcare provider prescribes. It’s important to stay on track with treatment. If you run out of medications or inhalers, be sure to let your provider know as soon as possible, even if you still feel well.
• Make a plan for high-altitude travel. Even those without underlying conditions can have trouble breathing at high altitudes. Understand how it might affect you, and make a plan to adjust to the change. Bring any extra equipment or medication you might need.

Complications of this condition

Your cells need oxygen to produce energy and help your organs and tissues to do their jobs. Some of your tissues can adjust to short-term dips in oxygen levels. But prolonged hypoxia can cause organ damage. Brain and heart damage are particularly dangerous. They can be fatal. Lack of oxygen to your brain is called cerebral hypoxia.

How doctors diagnose hypoxia

Your healthcare provider will perform a physical exam, including listening to your heart and lungs. They may check your skin, nails and lips to see whether they look bluish. Your provider may also order tests to check your oxygen levels and find the underlying cause of hypoxia. Tests may include:

• Pulse oximetry: Your healthcare provider places a sensor over your finger to measure the amount of oxygen in your blood. This is noninvasive and painless.
• Arterial blood gas test (ABG): A provider uses a thin needle to draw blood from your wrist, arm or groin to check your oxygen levels.
• Pulmonary function test (PFT): You blow out and breathe into a mouthpiece. It connects to a machine that measures how well your lungs work.
• Imaging: X-rays, CT scans, and VQ scans all use special equipment to get images of your internal organs. Imaging can help your provider find the cause of hypoxia.
• Six-minute walk test (6MWT): You walk on a flat surface for six minutes to see how far you can walk in that time. This test helps your provider evaluate your lung and heart function.
• Blood tests: Your provider may check your blood counts to ensure you have enough red blood cells. There are a variety of other blood tests providers use to diagnose specific conditions that may cause hypoxia.

How is it treated?

The treatment for hypoxia depends on the underlying cause. The cause might be a one-time event or a long-term condition. Treatments might include:

• Inhaled or oral steroids that can open up your airways to treat asthma or other lung diseases
• Antibiotics to treat pneumonia
• Blood thinners to treat blood clots or blood vessel disease
• Medications that help to reduce excess fluid in your lungs (diuretics)
• Continuous positive airways pressure (CPAP) mask to treat sleep apnea
• Bilevel positive airway pressure (BiPAP^®) to treat COPD and some kinds of sleep apnea
• Supplemental oxygen to bring more oxygen to your nose with a mask or tubes to treat ongoing (chronic) hypoxia
• Mechanical ventilation in a hospital if you have severe acute hypoxia (sudden onset)

When should I see my healthcare provider?

If you have symptoms like severe shortness of breath, confusion, rapid heart rate or rapid breathing — or if you notice your nails, lips or skin appear bluish — seek medical help right away. You need prompt treatment for hypoxia to prevent permanent organ damage.

Hypoxia can be a life-threatening condition. Go to the emergency room if you have any symptoms of hypoxia or if others notice that you’re suddenly confused, restless or have a change in consciousness. Go to the ER if the typical symptoms of a chronic condition get worse suddenly, or you have new symptoms that you think might be hypoxia.

Some people test their oxygen levels with devices they purchased for home use. While these can sometimes be helpful, they’re not always accurate. You shouldn’t rely on them to rule out the need for emergency care. Not all breathing problems cause drops in oxygen levels.

If you or a loved one gets a hypoxia diagnosis, you may want to ask your healthcare provider:

• Is hypoxia related to an underlying medical condition?
• How can I manage my condition to reduce my risk of hypoxia?
• Did this cause any organ damage or other issues?
• Are there any changes in lifestyle that could reduce my risk of hypoxia?

What can I expect if I have hypoxia?

Hypoxia usually requires prompt medical treatment. Your healthcare provider will talk to you about the underlying cause and how to manage it going forward.

The prognosis (outlook) for hypoxia depends on how severe it is, how healthy you are and what caused it. Some conditions that cause hypoxia are easier to treat than others. In some cases, treating the underlying issue takes care of the hypoxia. The need for extra oxygen goes away.

In other cases, you may need chronic supplemental oxygen to make sure there’s no ongoing hypoxia or tissue damage from low oxygen levels. Your provider will discuss your options with you.