Hypoxia

Hypoxia is a serious medical condition where your body’s tissues don’t receive enough oxygen. When oxygen levels drop too low, you might feel confused, restless, or struggle to breathe, and your skin may turn bluish. This condition can become life-threatening within minutes if not treated promptly.

Table of contents

• What is Hypoxia?
• The Difference Between Hypoxia and Hypoxemia
• Signs and Symptoms
• What Causes Hypoxia?
• Who is at Risk?
• How Hypoxia Affects Your Body
• How Doctors Diagnose Hypoxia
• Treatment and Management
• Prevention

What is Hypoxia?

Hypoxia occurs when the tissues of your body don’t have enough oxygen^[1]. To understand this condition, it helps to know how oxygen normally travels through your body. When you breathe, oxygen enters your lungs and travels through your airways into small sacks called alveoli (tiny air pockets in the lungs). From there, oxygen gets picked up by your blood in small vessels called capillaries that travel close to the alveoli. Finally, oxygen travels through your blood to reach all your tissues and organs^[1].

You can think of oxygen as passengers flying into an airport (your lungs). They get picked up and travel on highways (blood vessels) to reach their destinations (your tissues). As oxygen gets delivered, your blood picks up a waste product called carbon dioxide, which travels back to your lungs and exits your body when you breathe out^[1].

If not enough oxygen gets through at any point on this journey, it leads to hypoxia. Both airflow and blood flow are important to this process, which is why lung disease and heart disease both increase your risk^[1].

The Difference Between Hypoxia and Hypoxemia

You may hear the terms hypoxia and hypoxemia used as if they mean the same thing, but they aren’t identical. The names sound similar because they both involve a lack of oxygen, but in different parts of your body^[1].

Hypoxia means low oxygen levels in the tissues, while hypoxemia means low oxygen levels in the blood. Hypoxia is often caused by hypoxemia, but not always. You can be hypoxic without being hypoxemic and vice versa^[1].

Signs and Symptoms

Hypoxia symptoms vary depending on how severe the condition is, what caused it, and which parts of your body are affected. When your oxygen is low, you might feel like you can’t breathe or think properly^[1].

Common hypoxia symptoms include^[1]:

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

Severe hypoxia can cause additional symptoms^[1]:

• Slow heart rate (bradycardia)
• Extreme restlessness
• Bluish skin (cyanosis)

In some cases, you may also experience changes in skin color ranging from blue to cherry red, coughing, sweating, or wheezing^[8]. If you have symptoms of hypoxia, especially if you have an underlying heart or lung condition, call 911 or go to the nearest emergency room immediately^[1].

What Causes Hypoxia?

At the tissue level, there are two primary causes of hypoxia: low blood flow to the tissue or low oxygen content in the blood^[2]. Hypoxia is most often caused by an underlying illness that affects blood flow or breathing^[1].

Medical conditions that can lead to hypoxia include^[1]:

• Anemia
• Asthma
• Bronchitis
• Chronic obstructive pulmonary disease (COPD)
• Congenital heart defects
• Congestive heart failure
• Emphysema
• Pneumonia (bacterial and viral)
• 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

Hypoxia can also result from lung damage due to trauma, strong pain medicines and other drugs that slow breathing, carbon monoxide poisoning, or cyanide poisoning^[8]. Being at high altitudes can also cause hypoxia, which is why it can be hard to breathe when you’re in the mountains^[3].

Who is at Risk?

Any condition that reduces the amount of oxygen in your blood or restricts blood flow can cause hypoxia. People living with heart or lung diseases such as COPD, emphysema, or asthma are at an increased risk for hypoxia^[1].

Some infections also increase your risk of hypoxia, including pneumonia, influenza, and COVID-19^[1]. Sleep apnea and mild lung disease can cause nocturnal hypoxia, when your blood oxygen levels drop during sleep^[13].

How Hypoxia Affects Your Body

Your cells need oxygen to produce energy and help your organs and tissues do their jobs. While some of your tissues can adjust to temporary dips in oxygen levels, prolonged hypoxia can cause organ damage^[1].

Brain and heart damage are particularly dangerous and can lead to death. Lack of oxygen to your brain is called cerebral hypoxia^[1]. Without oxygen, your brain, liver, and other organs can be damaged just minutes after symptoms start^[8].

The response to hypoxia varies among tissues. While some tissues can tolerate certain forms of hypoxia or reduced blood flow for extended periods, others are significantly impaired by low oxygen levels^[2].

How Doctors Diagnose Hypoxia

Hypoxia can usually be diagnosed based on your medical history and a physical exam^[1]. Doctors use various methods to measure blood oxygen levels depending on your specific condition and treatment needs^[2].

Evaluation methods include^[2]:

Pulse oximetry is one of the fastest oxygen saturation tests. It uses a small, noninvasive device called a pulse oximeter that clips to your finger or earlobe. This device uses light and a sensor to measure how much oxygen is in your blood^[5]. A healthy, normal blood oxygen saturation level is 95 to 100 percent. Values under 90 percent are considered low^[5].

Arterial blood gas analysis measures levels of oxygen and the waste gas carbon dioxide with a blood sample taken from an artery^[5]. A healthy level of oxygen in the arteries is about 75 to 100 millimeters of mercury (mm Hg). Hypoxemia is any value under 60 mm Hg^[5].

Tests are also done to determine the cause of the hypoxia, and may include imaging tests, blood tests, or other assessments^[2].

Treatment and Management

Hypoxia is a medical emergency and should be treated promptly. Failure to start oxygen therapy can result in serious harm to the patient^[15]. If you are experiencing symptoms of hypoxia, call 911 or go to the nearest emergency room^[1].

You’ll need to go to the hospital to get treatment for hypoxia and to keep a check on your oxygen level. The most important thing is to get more oxygen into your body^[8].

Treatment approaches include^[8]:

You’ll receive oxygen through a small plug in your nose or through a mask that covers your nose and mouth. For many people, this is enough to bring your oxygen level up to normal. This treatment is called supplemental oxygen or oxygen therapy^[5].

An inhaler or asthma medicine by mouth may make breathing easier. If these don’t help, the doctor might try giving you medicine through a vein in your arm. You might need steroid drugs for a short time to shrink inflammation in your lungs or antibiotics to treat an underlying infection^[8].

When your life is in danger and other treatments aren’t working, you may need a machine to help you breathe^[8].

Hypoxia management focuses on maintaining airway patency, increasing inspired air oxygen content, and optimizing diffusion capacity^[2]. The target range for a normal adult is 92 to 98 percent oxygen saturation. For patients with COPD, the target range is 88 to 92 percent^[15].

Other treatments focus on the cause of the hypoxia. Timely recognition and treatment are crucial to prevent permanent organ damage and potential fatality^[2].

Prevention

The best way to prevent hypoxia is to manage any underlying conditions. If you have asthma, keep it under control every day by sticking with your asthma treatment plan^[8].

Preventive steps include^[8]:

• Take your medicine to help prevent flares and the need to use your rescue inhaler
• Eat right and stay active
• Know your asthma triggers and find ways to avoid them
• Work with your doctor to create an action plan for asthma attacks, so you know what to do when you have trouble breathing

If you smoke cigarettes, quit. Smoking cessation can be challenging, but with medical help, your circulation will improve substantially just two to three weeks after your final cigarette. Within one to nine months, your shortness of breath will diminish, and your oxygen saturation numbers will rise^[23].

Something as simple as opening your windows or heading outdoors for a walk can effectively increase the amount of oxygen you breathe in, which in turn increases your overall blood oxygen level^[23].