Carbon Monoxide Poisoning Health Article

Diagnosis

The main reason to suspect CO poisoning is evidence that fuel is being burned in a confined area, for example, a car running inside a closed garage, a charcoal grill burning indoors, or an unvented kerosene heater in a workshop. Under these circumstances, one or more persons suffering from the symptoms listed above strongly suggests CO poisoning. In the absence of some concrete reason to suspect CO poisoning, the disorder is often misdiagnosed as migraine headache, stroke, psychiatric illness, food poisoning, alcohol poisoning, or heart disease.

Concrete confirmation of CO poisoning comes from a carboxyhemoglobin test. This blood test measures the amount of CO that is bound to hemoglobin in the body. Blood is drawn as soon after suspected exposure to CO as possible.

Other tests that are useful in determining the extent of CO poisoning include measurement of other arterial blood gases and pH; a complete blood count; measurement of other blood components such as sodium, potassium, bicarbonate, urea nitrogen, and lactic acid; an electrocardiogram (ECG); and a chest x ray.

Treatment

Immediate treatment for CO poisoning is to remove the victim from the source of carbon monoxide gas and into fresh air. If the victim is not breathing and has no pulse, cardiopulmonary resuscitation (CPR) should be started. Depending on the severity of the poisoning, 100 percent oxygen may be given with a tight fitting mask as soon as it is available.

Taken with other symptoms of CO poisoning, COHb levels of over 25 percent in healthy individuals, over 15 percent in people with a history of heart or lung disease, and over 10 percent in pregnant women usually indicate the need for hospitalization. In the hospital, fluids and electrolytes are given to correct imbalances that have arisen from the breakdown of cellular metabolism.

In severe cases of CO poisoning, individuals are given hyperbaric oxygen therapy. This treatment involves placing the person in a chamber in which the person breathes 100 percent oxygen at a pressure of more than one atmosphere (the normal pressure the atmosphere exerts at sea level). The increased pressure forces more oxygen into the blood. Hyperbaric facilities are specialized and are usually available only at larger hospitals.

Prognosis

The speed and degree of recovery from CO poisoning depends on the length of exposure to the gas and the concentration of carbon monoxide. The half-life of CO in normal room air is four to five hours, which means that in four to five hours half of the CO bound to hemoglobin will be replaced with oxygen. At normal atmospheric pressures, but breathing 100 percent oxygen, the half-life for the elimination of CO from the body is 50 to 70 minutes. In hyperbaric therapy at three atmospheres of pressure, the half-life is reduced to between 20 and 25 minutes.

Although the symptoms of CO poisoning may subside in a few hours, some affected persons show memory problems, fatigue, confusion, and mood changes for two to four weeks after their exposure to the gas.

Prevention

Carbon monoxide poisoning is preventable. Particular care should be paid to situations where fuel is burned in a confined area. Portable and permanently installed carbon monoxide detectors that sound a warning similar to smoke detectors are available for under $50. Specific actions that prevent CO poisoning include the following:

• Stop smoking. Smokers have less tolerance to environmental CO.
• Have heating systems and appliances installed by a qualified contractor to assure that they are properly vented and meet local building codes.
• Inspect and properly maintain heating systems, chimneys, and appliances.
• Do not use a gas oven or stove to heat the home.
• Do not burn charcoal indoors.
• Make sure there is good ventilation if using a kerosene heater indoors.
• Do not leave cars or trucks running inside the garage.
• Keep car windows rolled up when stuck in heavy traffic, especially if inside a tunnel.