Carbon dioxide (co2) Health Dictionary

Carbon Dioxide (co2): From 1 Different Sources


Formed by the body during metabolism and exhaled by the lungs. Seen in sparkling waters and wines, it is also used in baths as a stimulant to the skin. Combined with oxygen in cylinders, it is used to control breathing in ANAESTHESIA and in the treatment of victims of CARBON MONOXIDE (CO) poisoning.

Measuring the partial pressure of the gas by taking blood for blood gas estimation provides information on the adequacy of breathing. A high partial pressure may indicate impending or actual respiratory failure.

Health Source: Medical Dictionary
Author: Health Dictionary

Carbon

A non-metallic element, the compounds of which are found in all living tissues and which is a constituent (as carbon dioxide) of air exhaled from the LUNGS. Two isotopes of carbon, 11C and 14C, are used in medicine. Carbon-11 is used in positron-emission tomography (see PET SCANNING); carbon-14 is used as a tracer element in studying various aspects of METABOLISM.... carbon

Carbon Dioxide

(CO) A colourless, odourless gas. Carbon dioxide is present in small amounts in the air and is an important by-product of metabolism in cells. It is produced by the breakdown of substances such as carbohydrates and fats to produce energy, and is carried in the blood to the lungs and exhaled. Carbon dioxide helps to control the rate of respiration: when a person exercises, CO2 levels in the blood rise, causing the person to breathe more rapidly in order to expel carbon dioxide and to take in more oxygen.

When it is compressed and cooled to -75ºC, carbon dioxide becomes solid dry ice, which is used in cryosurgery.... carbon dioxide

Carbon Monoxide

(CO) A colourless, odourless, poisonous gas present in motor exhaust fumes and produced by inefficient burning of coal, gas, or oil.

Carbon monoxide binds with haemoglobin and prevents the transportation of oxygen to body tissues.

The initial symptoms of acute high-level carbon monoxide poisoning are dizziness, headache, nausea, and faintness.

Continued inhalation of the gas may lead to loss of consciousness, permanent brain damage, and even death.

Low-level exposure to carbon monoxide over a period of time may cause fatigue, nausea, diarrhoea, abdominal pain, and general malaise.... carbon monoxide

Carbon Tetrachloride

(CCl) A colourless, poisonous, volatile chemical with a characteristic odour that is present in some home dry-cleaning fluids and industrial solvents. It can cause dizziness, confusion, and liver and kidney damage if it is inhaled or swallowed.... carbon tetrachloride

Carbon Monoxide (co)

This is a colourless, odourless, tasteless, nonirritating gas formed on incomplete combustion of organic fuels. Exposure to CO is frequently due to defective gas, oil or solid-fuel heating appliances. CO is a component of car exhaust fumes and deliberate exposure to these is a common method of suicide. Victims of ?res often suffer from CO poisoning. CO combines reversibly with oxygen-carrying sites of HAEMOGLOBIN (Hb) molecules with an a?nity 200 to 300 times greater than oxygen itself. The carboxyhaemoglobin (COHb) formed becomes unavailable for oxygen transportation. In addition the partial saturation of the Hb molecule results in tighter oxygen binding, impairing delivery to the tissues. CO also binds to MYOGLOBIN and respiratory cytochrome enzymes. Exposure to CO at levels of 500 parts per million (ppm) would be expected to cause mild symptoms only and exposure to levels of 4,000 ppm would be rapidly fatal.

Each year around 50 people in the United Kingdom are reported as dying from carbon monoxide poisoning, and experts have suggested that as many as 25,000 people a year are exposed to its effects within the home, but most cases are unrecognised, unreported and untreated, even though victims may suffer from long-term effects. This is regrettable, given that Napoleon’s surgeon, Larrey, recognised in the 18th century that soldiers were being poisoned by carbon monoxide when billeted in huts heated by woodburning stoves. In the USA it is estimated that 40,000 people a year attend emergency departments suffering from carbon monoxide poisoning. So prevention is clearly an important element in dealing with what is sometimes termed the ‘silent killer’. Safer designs of houses and heating systems, as well as wider public education on the dangers of carbon monoxide and its sources, are important.

Clinical effects of acute exposure resemble those of atmospheric HYPOXIA. Tissues and organs with high oxygen consumption are affected to a great extent. Common effects include headaches, weakness, fatigue, ?ushing, nausea, vomiting, irritability, dizziness, drowsiness, disorientation, incoordination, visual disturbances, TACHYCARDIA and HYPERVENTILATION. In severe cases drowsiness may progress rapidly to COMA. There may also be metabolic ACIDOSIS, HYPOKALAEMIA, CONVULSIONS, HYPOTENSION, respiratory depression, ECG changes and cardiovascular collapse. Cerebral OEDEMA is common and will lead to severe brain damage and focal neurological signs. Signi?cant abnormalities on physical examination include impaired short-term memory, abnormal Rhomberg’s test (standing unsupported with eyes closed) and unsteadiness of gait including heel-toe walking. Any one of these signs would classify the episode as severe. Victims’ skin may be coloured pink, though this is very rarely seen even in severe incidents. The venous blood may look ‘arterial’. Patients recovering from acute CO poisoning may suffer neurological sequelae including TREMOR, personality changes, memory impairment, visual loss, inability to concentrate and PARKINSONISM. Chronic low-level exposures may result in nausea, fatigue, headache, confusion, VOMITING, DIARRHOEA, abdominal pain and general malaise. They are often misdiagnosed as in?uenza or food poisoning.

First-aid treatment is to remove the victim from the source of exposure, ensure an e?ective airway and give 100-per-cent oxygen by tight-?tting mask. In hospital, management is largely suppportive, with oxygen administration. A blood sample for COHb level determination should be taken as soon as practicable and, if possible, before oxygen is given. Ideally, oxygen therapy should continue until the COHb level falls below 5 per cent. Patients with any history of unconsciousness, a COHb level greater than 20 per cent on arrival, any neurological signs, any cardiac arrhythmias or anyone who is pregnant should be referred for an expert opinion about possible treatment with hyperbaric oxygen, though this remains a controversial therapy. Hyperbaric oxygen therapy shortens the half-life of COHb, increases plasma oxygen transport and reverses the clinical effects resulting from acute exposures. Carbon monoxide is also an environmental poison and a component of cigarette smoke. Normal body COHb levels due to ENDOGENOUS CO production are 0.4 to

0.7 per cent. Non-smokers in urban areas may have level of 1–2 per cent as a result of environmental exposure. Smokers may have a COHb level of 5 to 6 per cent.... carbon monoxide (co)




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