Anoxia

Anoxia is when you have little or no oxygen in part or all of your body. It’s similar to hypoxia (low oxygen levels) but more severe. The name of this condition comes from ancient Greek words meaning “without oxygen.”

Anoxia is a medical emergency that needs quick, expert medical attention.

Anoxia is what happens when hypoxia gets worse. And some tissues, like your brain, have an extremely high demand for oxygen. That’s why brain anoxia can cause permanent brain damage and death in just a few minutes without prompt treatment.

What are the symptoms of anoxia?

People with anoxia are unconscious and unresponsive, meaning you can’t wake them up. They may also have the following symptoms:

• Cyanosis
• Slow pulse or no pulse
• Seizures or muscle twitching (myoclonus)

What causes anoxia?

Anoxia can happen several ways. All of them involve disruptions in your body’s oxygen supply. Some examples include:

• Breathing: Anoxia can happen when you physically can’t breathe or something’s blocking your airway.
• Oxygen transfer: Oxygen in your lungs may not pass into your blood like it should, causing low blood oxygen levels (hypoxemia), which then leads to anoxia.
• Circulation: Your blood may not circulate like it should, like if your heart stops (asystole) or if something blocks circulation. It can also happen if your blood pressure drops too low.

When your cells don’t get enough oxygen, ischemia happens. The longer ischemia lasts, the worse the damage will probably be. For some parts of your body, especially your brain, the damage from ischemia can become severe and permanent within minutes.

What kinds of events can cause anoxia?

Anoxia can happen for many reasons, including:

• Breathing disruptions that cause asphyxiation, like paralysis, drowning or anaphylaxis
• Conditions that block circulation internally — especially in your lungs — like pulmonary embolisms
• Conditions that interfere with oxygen transfer, like lung damage from inhalation burns or toxic fumes
• Conditions that stop your heart or cause cardiogenic shock, like heart attacks or arrhythmias, or drug overdoses (either from prescription or nonprescription drug use)
• Severe altitude sickness because there’s less available oxygen above 11,000 feet (3,352 meters)
• Injuries that cause severe blood loss (hemorrhage)
• Toxic effects like carbon monoxide poisoning

What are the complications of anoxia?

Anoxia is dangerous because it means your body isn’t getting enough oxygen. Some tissues, especially your brain, are more sensitive to that. That can lead to:

• Hypoxic-ischemic brain damage
• Coma or persistent vegetative state
• Brain death
• Death

How is anoxia diagnosed?

A healthcare provider can diagnose anoxia using a physical exam and a variety of tests.

Possible tests include:

• Blood oxygen level measurements using a pulse oximeter
• Lab tests on your blood, like an arterial blood gas test
• Pulmonary (lung) function tests
• Imaging tests like CT scans or VQ scans

Some tests are also possible for diagnosing lingering damage or effects from hypoxia. One example of that is magnetic resonance imaging (MRI), especially brain MRI.

How is anoxia treated?

Treating anoxia depends partly on why it happened. Oxygen therapy is a common part of treating anoxia (or conditions that could cause it). This provides higher concentrations of oxygen than regular air.

When someone is unresponsive or isn’t breathing, first responders check the ABCs to start treatment or prevent anoxia. The ABCs stand for:

• Airway: It needs to be clear and open.
• Breathing: If you aren’t breathing, you’ll need mechanical ventilation to breathe for you.
• Circulation: If your heart is beating, you’ll have a pulse. If you don’t have a pulse, you need CPR.

People with anoxia are unconscious. When that happens, healthcare decision-making falls to someone empowered to make those choices. That’s usually a loved one or someone legally chosen and named in an advance directive.

Many other treatments are possible, depending on the underlying cause of anoxia. A healthcare provider can explain the treatment options for your situation.

What’s the outlook for anoxia?

The outlook for anoxia depends mainly on two factors:

• What caused it: The outlook is better when the cause is reversible.
• How long it lasted: The shorter anoxia lasts, the better the chances of recovery.

Brain damage can start after three to five minutes of anoxia. If it lasts longer than six to 10 minutes, permanent brain damage or brain death is more likely. Once brain death happens, life support treatments can keep your body alive temporarily, but death will happen without them.

But several other factors can determine whether anoxia causes permanent damage. And in many cases, follow-up testing is necessary before a healthcare provider can tell you about what’s most likely to happen.

Can anoxia be prevented?

Anoxia isn’t 100% preventable. But there are a few things you can do to reduce your risk of it happening. They mainly revolve around preventing conditions or situations that could lead to anoxia. Examples include:

• Wearing proper safety gear (like life jackets) when swimming or around bodies of water to prevent drowning
• Supervising children around water and limiting access when no supervision is available
• Installing and maintaining smoke and carbon monoxide detectors in your home
• Managing conditions that could cause anoxia, like heart disease, arrhythmias or clotting disorders

Knowing lifesaving techniques can also help if you’re with someone who’s at risk for anoxia. These include:

• Putting someone in the recovery position: To do this, lie the person on their side. Position the arm on the ground side to prop up their head (so they use their bicep like a pillow).
• CPR: This keeps blood circulating, helping the brain get oxygen.
• The Heimlich maneuver: It can clear a person’s airway if they’re choking (and there are ways to do it on yourself if you’re alone).

When should I go to the emergency room?

Any condition that stops your heart or breathing is a medical emergency. You should call 911 (or your local emergency number) immediately if this happens to someone you’re with. When in doubt, act quickly, as it could save a life.