Best practice & research. Clinical anaesthesiology
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Elderly patients represent the majority of the surgical population scheduled for ophthalmological surgery. Eye surgery is usually minimally invasive, enabling most of the procedures to be performed as day-case surgery despite the high co-morbidity of these patients. This, however, requires a specific perioperative anaesthetic strategy. In this chapter we address features of perioperative care in the geriatric population undergoing eye surgery, from pre-medication and pre-operative testing, to choice and performance of anaesthesia, and finally to post-anaesthesia care.
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An overview is given of the influence of age on the pharmacodynamics of drugs used during general and locoregional anaesthesia. For some groups of agents a distinct separation into age-related changes in the pharmacokinetics and pharmacodynamics is possible, whereas for others the literature indicates only that responses in the elderly are enhanced. I start with an overview of the influence of age on cardiovascular and neuroendocrine function and include a short account of the state-of-the-art in pharmacodynamic modelling. ⋯ For opioids and local anaesthetics applied for blockade of the central nervous system, the pharmacodynamic involvement is not always clear. For neuromuscular blocking agents, pharmacodynamic involvement appears to be nearly absent in the reduced dose requirements seen with age--so that the latter appear to be caused by altered pharmacokinetics. Future studies, using pharmacokinetic-pharmacodynamic (PK-PD) mixed-effects modelling, should further explore this area to obtain clinically applicable data for improving our insight into the delivery of anaesthetics to the elderly and improving the quality of anaesthesia in this fast-growing population.
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Best Pract Res Clin Anaesthesiol · Jun 2003
ReviewThe ethics of end-of-life decisions in the elderly: deliberations from the ECOPE study.
Is age a factor underlying clinical decision-making? Should age be a criterion in the allocation of health care resources? Is it correct to criticize this approach as 'ageism'? What role does 'paternalism' play? These questions are the focus of this chapter which takes an interdisciplinary perspective of clinical ethics in order to provide an ethical evaluation of the situation of the elderly in health care. First, the text of the chapter is based on the descriptive level referring to (a) clinical ethics consultation, (b) the ECOPE study on 'Ethical Conditions of Passive Euthanasia' focusing on decision-making, and studies about age as a factor in clinical decisions, such as the American SUPPORT study. Second, at the normative level, ethical deliberations are discussed for and against age as a criterion for allocating health care resources. Finally, it is suggested that the differences in evidence to be found about the role of age as a factor in clinical decision-making may be due to the different national health policies as well as to the insufficient awareness of ethical principles violated by covert 'ageist' attitudes.
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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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Toxicology has matured since it was defined as the 'science of poisons'. Modern toxicology is no longer anthropocentric but takes on different views at various biological systems, including ecosystems. Each will interact specifically when exposed to defined chemical agents, including drugs. ⋯ The key to understanding is in the host proteins that interact with the drug and mediate the cellular response. Hence, the proteom, i.e. the complete set of proteins of a cell, an individual or a species, determines how an exposed biological system may interact with the manifold of different xenobiotics. Structure-activity studies try to find out useful predictive parameters for risk and toxicity assessment.