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If you are a frequent underwater-dweller, you may have heard discussions regarding a condition called Hypoxia.

Simply put – Hypoxia is a lack of oxygen to the brain and can be fatal if you are not diligent in seeking treatment as soon as possible.

Those who have experienced symptoms of Hypoxia and have been treated may still experience side effects long after treatment has been completed.

How Does Hypoxia Happen?

In order for your body to function properly, your brain relies on your blood to supply a continuous flow of oxygen. Any type of disruption to this supply of oxygen can cause issues and your body will begin to signal you that something is wrong.

If noting is done to remedy this oxygen flow problem, you will enter Hypoxia.

1. Blood Supply to the Brain is Cut Off

Blood supply is cut off when blood vessels that are carrying blood flow are cut off or blocked. When this happens, it is typically fatal.

2. Little to No Blood Supply to the Brain

This most frequently happens when a person suffers a stroke. Lower blood supply to the brain happens when one blood vessel is blocked or obstructed and impacts one specific area of the brain and affects functions that occur within that one section of the brain.

3. No Blood Saturated Oxygen is Reaching the Brain

This becomes fatal very quickly and occurs when oxygen is not reaching the heart, lungs, and brain. All organs within the body begin to suffer from hypoxia.

4. Little to No Blood Oxygen

Illnesses such as a heart attack can cause low blood oxygen and the brain starts receiving less blood than it needs to properly function. It quickly signals the rest of the body and organs that something is wrong.

More Signs and Symptoms

Hypoxia can be tricky to identify because the symptoms could easily be confused with other conditions.

Some common signs to watch out for are: shortness of breath, rapid breathing, an elevated heart rate, inability to speak clearly, or a state of confusion.

1. Skin Color Becomes Paler

When blood supply becomes alarmingly low, this often causes skin color to change. Keep note of any sudden changes in overall skin color and appearance.

2. Heart Beat Increase/Decrease

When oxygen is struggling to reach the brain and lungs, the heart begins to pump faster in an attempt to reach all the organs in the body at a much faster rate. When this happens, it can put sudden strain on the heart and organs and should be noted immediately.

3. Sudden Shortness of Breath or Wheezing

When oxygen is reduced in the body, breathing will become more difficult and cause people to struggle to intake enough air. This can also cause the person to black out due to a lack of oxygen.

4. Confused State of Mind

With an inability to reach proper oxygen levels, a state of confusion often takes hold and leaves the sufferer in a daze due to disorientation.

If you notice any of these symptoms or something just feels off, seek medical attention immediately.

scuba training

Primary Causes for Hypoxia

Divers and swimmers are not the only ones who need to worry about a risk of hypoxia. There are numerous activities, illnesses, or injuries that can cause a lack of proper oxygen supply to the brain.

These include:

  • Reaching a high altitude – this is especially a health concern for people who are in poor health or who have trouble breathing in normal altitude conditions
  • Inhalation of carbon monoxide, cigarette smoking, or smoke caused from a fire
  • Smothering or strangulation – This can cause oxygen issues even in a very short period of time.
  • Low blood pressure
  • Choking – Because there is a foreign object blocking oxygen from entering the lungs, this can cause hypoxia to take hold
  • Stroke or heart attack
  • Asthma
  • Sleep apnea – Many people suffer from this condition at night and it causes oxygen to struggle to reach the lungs, which then causes a decrease in heartbeat
  • Panic attacks or hyperventilation – When a panic attack takes hold, this can cause people to struggle to breathe properly, which causes a lack of oxygen in the body

Increased Risk of Hypoxia in Freediving

Divers who participate in freediving may find that they have an increased risk of developing hypoxia, due to the long periods of time spent underwater while holding their breath.

Long periods of time underwater can cause pressure buildup in the ear canal, which can also trigger signs of hypoxia.

Some experts have suggested placing bans on specific types of long period dives, but this creates worry that people who still want to practice these types of dives will do so in an unregulated area or without proper supervision. The dives can be performed safely, but it is important to take the proper precautions.

Many people who experience these signs are otherwise healthy individuals and the symptoms can impact those who are well-practiced divers and swimmers. This is not simply a condition that people only need to worry about as novice divers that they will eventually out-train.

Treatment for Hypoxia

If Hypoxia is triggered due to asthma, it is vital that the patient receives proper treatment using their prescribed inhaler. This helps the muscles in their airway to relax and gives time for proper oxygen to flow through the passageways. In any other cases, an oxygen mask is typically applied to the patient, which allows for a quick entryway for oxygen to reach the lungs and supply enough oxygen to the blood.

In more serious cases, a steroid shot is injected to reduce overall inflammation in the lungs. This can also encourage the patient to take a deep breath, which can more quickly help oxygen reach the lung pathways.

Hypoxia is extremely serious and can quickly become fatal if it is not properly treated. While it is recommended to avoid activities that could lead to developing signs of hypoxia, this is not always desirable for divers and swimmers.

What is most important is to listen to your body and if it is telling something is off or you are noticing any of the above described symptoms, seek treatment. It is always better to err on the side of caution and take care of yourself.

Types of Blackouts During Hypoxia

There are different types of blackouts that can occur while practicing freediving. They are as follows:

Ascent Blackout

Some divers experience dizziness or fainting once they reach the top of the water. This is caused by the pressure of oxygen in the lungs that drops to reach surface volume once the diver reaches the initial surface of the water. They may attempt to breath normally again, but it can trigger an immediate blackout due to the oxygen being unable to reach the brain in time to reach equilibrium.

Constant Pressure Blackout

This can occur in shallow water diving, where there is not a significant amount of pressure on the lungs but is typically caused by hyperventilation in the diver.

Surface Blackout

This occurs when a diver has low levels of oxygen following a dive and long period of breath holding, but the oxygen they have inhaled since surfacing has not yet had time to reach the diver’s brain. This results in a latent blackout.

Preventative Measures to Avoid Hypoxia 

One study found that Japanese free divers experience a low rate of blackouts while diving because they follow a safe and conservative diving schedule. This involves limiting their total individual dive duration to one minute, resting and breathing between dives, and splitting their dives into shorter sessions.

By eliminating longer free dives, this helped to decrease the risk of developing hypoxia, while still allowing them to enjoy the sport.

Before any dive, divers should try to relax and allow their blood oxygen to circulate. Immediately before submerging, the diver should take one deep breath at optimal capacity.

Divers should also avoid free diving alone, with one diver observing the submerged diver to ensure safety throughout the duration of the dive. If the observing diver notes any trouble, they can attempt an immediate rescue to bring the diver to the surface.

Some signs that the observing diver should look for are as follows:

  • If the diver stops swimming or becomes motionless for any reason
  • The diver begins to sink
  • Their arms or legs seem to have gone limp or their head falls forward
  • Their body begins to spasm or twitch

Upon retrieval of the diver to the surface, the observing diver should remove the diver’s mask to see if this triggers initial breathing.

Immediate medical attention should be retrieved at first notice of any signs of hypoxia.

underwater oxygen

Final Thoughts on Hypoxia While in the Water

Anyone who decides to take part in any form of swimming or diving should take special precautions to ensure their safety.

While any kind of water sport can be an extremely enjoyable, they can also be dangerous if the proper precautions are not taken. No one is immune to blackouts or hypoxia and these conditions can cause permanent damage in the long run.

Be safe and be sure to take the proper precautions to ensure you stay safe.

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