What is carbon monoxide (CO) poisoning?

Carbon monoxide (CO) is a colorless, odorless, tasteless gas. CO is found in combustion fumes. CO poisoning is usually caused by car or truck exhaust, wood stoves, and other fuel burning appliances. It can be caused by any of these:

• Smoke from a fire or blocked fireplace

• Nonelectric heaters

• Faulty gas appliances

• Faulty heating exhaust in the home or garage

CO is known as a silent killer. It displaces the oxygen in the bloodstream when the CO is mixed in the normal air you breathe. If a heater's combustion system fails and CO seeps out of it, the gas can kill people while they are asleep. CO poisoning can happen:

• At home

• In a garage or car

• In an enclosed space like a camper, trailer, or tent

Any person is at risk for CO poisoning from combustion fumes. The risk is higher during the winter when windows are closed. Some people are more at risk than others. These include:

• Babies

• Pregnant people

• People with heart problems,

• People with breathing problems

• People with anemia

How CO poisoning is treated

CO poisoning is a medical emergency. Its main symptoms are:

• Headache (most common)

• Nausea

• Dizziness

• Vomiting

• Weakness

• Chest pain

• Confusion

More severe CO poisoning leads to loss of consciousness and death.

Get out of the area where CO gas is present or suspected. Call 911. The emergency medical team will likely use a face mask to give pure oxygen. This is the most common treatment for CO poisoning. The face mask is used for about 4 hours. If the person has trouble breathing on their own, they may be put on a machine that helps them breathe.

Hyperbaric oxygen therapy (HBOT) for CO poisoning

CO poisoning in many people can be reversed without HBOT. But studies have shown that in some cases, HBOT can lower the risk for brain injury and nerve damage. HBOT is often advised for pregnant people with high levels of carbon monoxide.

Many hospitals do not have a hyperbaric chamber. The person may be sent by ambulance or helicopter to a hospital that has one. HBOT is more expensive than a face mask to deliver oxygen.

What is decompression sickness (DCS)?

Decompression sickness (DCS) is when bubbles of nitrogen and other gases form in the bloodstream. It is a rare condition that can happen in:

• Deep sea divers

• Aviators

• Miners

• Astronauts

• Mountain climbers

• People who work at high or low altitudes

It can happen as a person returns quickly to a normal altitude from these heights or depths.

The nitrogen bubbles in the blood can cause dangerous symptoms throughout the body. The most common symptom is extreme, crippling joint pain at the shoulders, knees, elbows, and ankles. This pain is often referred to as the bends.

People with DCS may also have:

• Headaches

• Dizziness

• Extreme fatigue

• Ringing in the ears

• Vision problems

• Chest pain

• Shortness of breath

• Skin rash and itching

• Malaise

• Numbness

• Paralysis

• Staggering

• Coughing up blood

• Collapse

In rare cases, people with DCS can go into shock and die if not treated.

Divers using compressed air are at high risk for DCS. DCS can happen if they come to the surface too quickly. People who are older, heavier, or less physically active have a higher risk.

Hyperbaric oxygen therapy (HBOT) for DCS

HBOT is the main treatment for DCS. The therapy:

• Instantly reduces the amount of nitrogen bubbles in the bloodstream

• Fills body tissues with oxygen

• Reduces dangerous swelling

In most cases, it's vital to get treatment as soon as possible, because the symptoms of DCS can be life-threatening. Even if your symptoms disappear when you return to a normal altitude, you should still get medical attention and possibly have HBOT to prevent long-term damage.

Side effects of hyperbaric oxygen therapy

HBOT lasts for a few hours. It may need to be repeated. The treatment may have side effects in some people. For example:

• Your ears may pop or you have mild discomfort in the chamber. These can be eased as the pressure is lowered.

• You may feel lightheaded when leaving the chamber.

• You may have nearsightedness after treatment. This usually gets better within days to weeks after the last treatment.

In rare cases, a person may have an eardrum rupture, lung symptoms, or a seizure. Having HBOT at a hospital with trained staff is the best way to prevent serious side effects.