Best practice & research. Clinical anaesthesiology
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The complications of failure, neural injury and local anaesthetic toxicity are common to all regional anaesthetic techniques, and individual techniques are associated with specific complications. All potential candidates for regional anaesthesia should be thoroughly evaluated and informed of potential complications. Central neural blockades still account for more than 70% of regional anaesthesia procedures. ⋯ Pain on injection and paraesthesias while performing regional anaesthesia are danger signals of potential injury and must not be ignored. The incidence of systemic toxicity to local anaesthetics has significantly decreased in the past 30 years, from 0.2 to 0.01%. Peripheral nerve blocks are associated with the highest incidence of systemic toxicity (7.5 per 10,000) and the lowest incidence of serious neural injury (1.9 per 10,000).
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Nitrous oxide interacts with vitamin B12 resulting in selective inhibition of methionine synthase, a key enzyme in methionine and folate metabolism. Thus, nitrous oxide may alter one-carbon and methyl-group transfer most important for DNA, purine and thymidylate synthesis. Long-term exposure to high concentrations of nitrous oxide may cause megaloblastic bone-marrow depression and neurological symptoms. ⋯ Recent studies seem to suggest a correlation between nitrous oxide anaesthesia and hyperhomocysteinaemia which is accepted to be an independent risk factor for coronary artery disease. As for today, available data do not support the notion that exposure to trace amounts of nitrous oxide is associated with impaired fertility or an increased risk of developing cancer. Emission of nitrous oxide from medical use is estimated to contribute less than 0.05% to total annual greenhouse gas emission.
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Intravenous anaesthetic agents are generally remarkably safe. However, it is clear that propofol infusion syndrome is a real, albeit rare, entity. This often lethal syndrome of metabolic acidosis, acute cardiomyopathy and skeletal myopathy is strongly associated with infusions of propofol at rates of 5 mg/kg/hour and greater for more than 48 hours. ⋯ Midazolam causes seizure-like activity in very-low-birthweight premature infants requiring the drug prior to tracheal intubation or during prolonged positive pressure ventilation. This can be successfully reversed with the specific benzodiazepine antagonist flumazenil. Midazolam can also cause paradoxical reactions, including increased agitation, poor co-operation and aggressive or violent behaviour, which has been successfully managed with flumazenil.
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Best Pract Res Clin Anaesthesiol · Mar 2003
ReviewOccupational hazards of inhalational anaesthetics.
Occupational exposure to inhalational anaesthetics has often been associated with health hazards and reproductive toxicity, but the available evidence is weak and comes mostly from epidemiological studies that have been criticized. Studies based on registered data generally showed no association between occupational exposure to inhalational anaesthetics and reproductive effects. Animal studies also showed a lack of carcinogenicity, organ toxicity and reproductive effects with trace concentrations, as observed in operating rooms. ⋯ Occupational exposure has also been associated with impairment of psychological functions, but these effects do not occur with trace concentrations. All in all, the scientific evidence for hazards is weak. Nonetheless, it is good practice to limit levels of exposure.
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Unwanted side-effects of anaesthetic drugs that occur during anaesthesia or during the post-operative recovery period are what concern anaesthesiologists and anaesthetists. Occupational risks are of concern to all health-care professionals who administer anaesthetics or who are incidentally exposed to anaesthetic gases. After regulatory requirements for marketing drugs are met, the qualitative and quantitative nature of side-effects of the drugs in the target population and the risk of incidental exposure of health-care professionals are generally well defined. ⋯ Numerous scientific disciplines with specialized terminology contribute to the body of knowledge about anaesthetic toxicity. Scientific inquiry spanning a range of disciplines from molecular biology to global ecology provides information essential for predicting, assessing, avoiding and treating the untoward effects of anaesthetics. Contemporary concerns with respect to side-effects of anaesthetic drugs include delayed recovery of cognitive function, addiction and tolerance, local anaesthetic cardiotoxicity and tissue toxicity, relative toxicity of enantiomeric forms of drugs, and the role of biotransformation in unwanted responses to anaesthetic drug administration.