Complete recovery of mental functioning post exposure was also noted. John Scott Haldane and his son JBS Haldane reported decrements in their ability to do arithmetic calculations as their carboxyhaemoglobin (COHb) levels rose during experimental exposure to CO. Short term exposure to high concentrations of carbon monoxide certainly produces changes in intellectual functioning. It has been generally assumed that such effects only occur after severe poisoning.
Other sequelae may include intellectual deterioration, memory impairment, and changes in emotional stability. 4 Damage to the striatum provides an explanation for the Parkinsonian signs that may follow severe poisoning with carbon monoxide. The striatum is also reported to have a high oxygen consumption.
The reasons for this are incompletely understood, though the fact that parts of the striatum lie at the boundary of the arterial supply from the anterior and middle cerebral arteries may be significant. Damage may be widespread, though the corpus striatum seems particularly vulnerable.
#SIGNS OF CARBON MONOXIDE POISONING FREE#
3 Free radical release may lead to lipoperoxidation, with the release of inflammatory mediators and the subsequent influx of neutrophils along a chemotactic gradient. Reperfusion injury is known to play a part in the damage produced by myocardial infarction. The mechanisms underlying the neurological damage are imperfectly known, but are thought to include an inflammatory response that may be initiated during the reperfusion or recovery phase when blood with increasing levels of oxygen flows into tissues that had hitherto been severely hypoxic. 2 Severe poisoning, leading to a period of unconsciousness, may lead to neurological damage that may be long lasting, though eventual recovery seems to be the general rule. 1 A short account has been provided by the Expert Panel on Air Quality Standards. In 1999, a WHO expert group reviewed the subject and reported their conclusions in Environmental Health Criteria 213, Carbon Monoxide. This produces a range of effects on health. The very effective competition of carbon monoxide with oxygen for binding sites on haemoglobin with the subsequent left shift of the dissociation curve leads to a reduction in both oxygen transport and release. The effects of severe exposure to carbon monoxide are well understood. Although there are as yet no conclusive studies showing such a correlation, the evidence in its favour is accumulating. Anecdotal evidence suggests that chronic exposure to CO may produce mild neurological effects. Patients are sometimes exposed to short periods of acute intoxication, in addition to the low level, chronic exposure thus the difficulty in determining which type of exposure is responsible for any subsequent health problems. Exposures in long term case studies are often of unknown levels and duration.
Studies of carbon monoxide exposure focus mainly on short term effects in experimental settings, or on long term effects in cases of accidental poisoning. The effects on health of prolonged but low level exposure to carbon monoxide (CO) are unclear.
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