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.... Medical Dictionary
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 e?ects within the home, but most cases are unrecognised, unreported and untreated, even though victims may su?er from long-term e?ects. 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 su?ering 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 e?ects of acute exposure resemble those of atmospheric HYPOXIA. Tissues and organs with high oxygen consumption are a?ected to a great extent. Common e?ects 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 su?er 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 e?ects 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.... Medical Dictionary
Because of its possible toxic e?ects – including kidney damage – lithium must only be administered under medical supervision and with monitoring of the blood levels, as the gap between therapeutic and toxic concentrations is narrow. Due to the risk of its damaging the unborn child, it should not be prescribed, unless absolutely necessary, during pregnancy – particularly not in the ?rst three months. Mothers should not take it while breast feeding, as it is excreted in the milk in high concentrations. The drug should not be taken with DIURETICS.... Medical Dictionary