Carbon Monoxide Poisoning: Causes, Symptoms and Treatment

Carbon monoxide is a colorless, odorless gas that is produced due to incomplete combustion of carbon based fuels. It can also be caused due to improper installation of certain appliances and lack of proper ventilation. It is also known as the 'silent killer' as it can't be seen or smelt. Although small doses cause mild symptoms like nausea and dizziness, large doses can cause brain damage and even death. It is believed to claim around 500 lives every year.

Sources and Causes
Carbon monoxide is created due to combustion of certain fuels in absence of proper levels of oxygen. Common sources of carbon monoxide are motor vehicle exhaust, smoke from fire and fumes from engines. Certain appliances at home also produce this poisonous gas when they are not functioning properly. Common sources of this gas inside a house or a building are malfunctioning cooking appliances, water heater, gas clothes dryers, unvented supplemental heaters, oil, gas or coal furnaces that are not maintained properly. Lack of proper ventilation also adds to an increase in the concentration of the toxic gas in a room. For example, not only does a choked chimney cut down the supply of oxygen required for production of carbon dioxide instead of carbon monoxide, it also traps the carbon monoxide produced due to incomplete combustion of fuels.

Symptoms
Hemoglobin which is the red pigment in the red blood cells carries oxygen to the tissues within the body. However, carbon monoxide has a high affinity to the iron sites in hemoglobin to which oxygen molecules get attached during their transfer from lungs to different parts of the body. When human beings are exposed to high levels of carbon monoxide, the molecules of this gas attach to hemoglobin molecules more readily than oxygen due to their stronger affinity for hemoglobin molecules than oxygen. The compound thus formed is called carboxyhemoglobin. It is this compound which is believed to be the major cause of carbon monoxide poisoning. Due to preferential attachment of hemoglobin with carbon monoxide molecules when they are present in inhaled air, there isn't enough hemoglobin free to transport oxygen. Moreover, if carbon monoxide attaches to any one of the four oxygen binding sites of hemoglobin, the affinity of oxygen for the other three sites increases. Therefore, even if a hemoglobin molecule is carrying three oxygen molecules, it will not deliver them to the tissues. In either case, the tissues are starved of oxygen which hampers the chemical processes going on in their cells. This creates a condition known as hypoxic injury to the tissues.

The poisoning can be detected by these commonly occurring symptoms:

• Headache
• Dizziness
• Nausea
• Chest pain
• Shortness of breath
• Vomiting
• Abdominal pain
• Drowsiness
• Fainting
• Seizures

Treatment
In case carbon monoxide poisoning is suspected, all affected individuals should be moved away from the area to a place with enough supply of fresh air. If someone has stopped breathing, CPR (cardiopulmonary resuscitation) may have to be administered. Every person should be tested for poisoning from carbon monoxide and proper medical treatment should be given.

Medical treatment includes:

• Providing high doses of oxygen using a face mask from an oxygen reserve bag. High levels of oxygen helps carbon monoxide to dissociate from hemoglobin. Hence, the hemoglobin is now free to carry oxygen to the various cells of the body.
• In case a person has inhaled high doses of carbon monoxide and has suffered from severe poisoning, higher doses of oxygen may be given to him using a hyperbaric chamber. Hyperbaric oxygen therapy is supposed to hasten the process of breaking down of carboxyhemoglobin. Hyperbaric oxygen also directly provides oxygen to the tissues. Hence, it is more effective than giving oxygen through an oxygen reservoir bag.

There is no home remedy for poisoning caused by carbon monoxide. The only way to prevent one's family from this hazard is to keep the home appliances in proper working condition and maintain proper ventilation in the house.