Definition Carbon monoxide (CO) is an odourless, tasteless, colourless, and poisonous gas. Carbon monoxide poisoning is a life-threatening condition caused by inhaling too much CO.
What is going on in the body? Carbon monoxide is produced when a fuel, such as gas, oil, kerosene, charcoal, or wood, is burned. CO may be found in a number of items that are used by people every day. These include:
leaking exhaust systems from internal combustion engines or motor powered vehicles
sewers
cellars
mines
faulty gas stoves or heating systems without good ventilation
fires
industrial plants
cigarette smoking, or breathing in second hand smoke
If fresh air circulation is limited and CO is released in the air, it can reach a dangerously high level. When CO is inhaled, it enters the bloodstream and attaches to a blood cell protein called haemoglobin. Haemoglobin helps blood cells carry oxygen from the lungs to the rest of the body. If CO attaches to haemoglobin, the blood cells are unable to carry oxygen. The body then can't get enough oxygen and is unable to function normally.
What are the signs and symptoms of the condition? Symptoms associated with CO poisoning include:
What are the causes and risks of the condition? CO poisoning can occur when small amounts of CO are inhaled over a long time. It can also occur when large amounts of CO are absorbed over a short time, especially in a closed setting like a garage or automobile.
What can be done to prevent the condition? Since CO is odourless and colourless, a person may not realize he or she is around dangerous levels of CO. Someone can prevent CO poisoning by:
keeping appliances in proper working order
using appliances correctly, and having them inspected regularly
making sure there is good ventilation before using gas powered engines or chemicals, such as paint remover
having chimneys checked to be sure flue is open and connected properly before using a fireplace
never leaving a car in idle when it is inside a garage
not sleeping in a room with a gas or kerosene space heater if it is not properly vented
installing carbon monoxide detectors in the house as a backup
moving into a well-ventilated area if any CO poisoning symptoms develop
calling the local gas company if there is a possible or suspected gas leak in the home
How is the condition diagnosed? A history of activity or illness as well as a complete physical examination helps to diagnose this condition. A series of blood tests called an arterial blood gas test can measure the oxygen and CO levels in the blood. Other blood or x-ray tests can evaluate the extent of the CO poisoning and rule out other conditions.
What are the long-term effects of the condition? Long-term effects of CO exposure depend on the extent of the poisoning and how quickly treatment is obtained. Possible long-term effects include damage to the brain, heart, or lungs. Short-term memory can also be affected. These effects usually improve over time, but may be permanent.
What are the risks to others? CO poisoning is not contagious. However, people who were near the affected person may also have been exposed to the carbon monoxide.
What are the treatments for the condition? The first treatment for CO poisoning is to remove the person from the CO and into fresh air. Further treatment depends on the extent of poisoning. Oxygen through a tight fitting mask, intravenous fluids, as well as medications including steroids may also be required. A ventilator, or artificial breathing machine, may be required if the lungs have been affected. At times, sedatives may also be used to decrease any excitability caused by the CO build-up in the body.
What are the side effects of the treatments? Side effects will depend on the treatments used. For instance, steroids may cause irritability, weight gain, or stomach upset. A ventilator can cause residual lung problems.
What happens after treatment for the condition? Often a person will recover with no need for further treatment. Physiotherapy or other treatments may be needed for problems such as paralysis and memory loss.
How is the condition monitored? Close monitoring is needed in cases of CO poisoning. It is possible for a person to experience delayed symptoms, such as confusion, fatigue, memory loss, or weakness. Any new or worsening symptoms should be reported to the doctor.
Author: Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 17/06/2005 Contributors Potential conflict of interest information for reviewers available on request
