Anaesthetics and postoperative cognitive dysfunction: a pathological mechanism mimicking Alzheimer's disease.

With longevity, postoperative cognitive decline in the elderly has emerged as a major health concern for which several factors have been implicated, one of the most recent being the role of anaesthetics. Interactions of anaesthetic agents and different targets have been studied at the molecular, cellular and structural anatomical levels. Recent in vitro nuclear magnetic resonance spectroscopy studies have shown that several anaesthetics act on the oligomerisation of amyloid beta peptide. Uncontrolled production, oligomerisation and deposition of amyloid beta peptide, with subsequent development of amyloid plaques, are fundamental steps in the generation of Alzheimer's disease. Amyloid beta peptide is naturally present in the central nervous system, and is found at higher tissue concentrations in the elderly. We argue that administering certain general anaesthetics to elderly patients may worsen amyloid beta peptide oligomerisation and deposition and thus increase the risk of developing postoperative cognitive dysfunction. The aim of this review is to highlight the clinical aspects of postoperative cognitive dysfunction and to find plausible links between possible anaesthetic effects and the molecular pathological mechanism of Alzheimer's disease. It is hoped that our hypothesis will stimulate further enquiry, especially triggering research into elucidating those anaesthetics that may be more suitable when cognitive dysfunction is a particular concern.

Genotoxic effects of anesthetic agents.

BACKGROUND: Preliminary research results indicate that exposure to anesthetics affects health. OBJECTIVE: To provide, with evidence-based knowledge, the answer to the question: What are the genotoxic effects threatening people exposed to anesthetics? METHOD: A systematic review of scientific literature. A systematic search of The Cochrane Library, MedLine, and CINAHL resulted in a screening of 212 abstracts of which 54 articles were assessed for quality. The 54 articles assessed covered areas on general health effects (neurobehavioral effects, immunology) and, in particular, genotoxic effects. RESULTS/CONCLUSION: In the scientific literature reviewed, there is evidence of exposure to anesthetics, especially nitrous oxide and halogenated gases, being associated with general health and genotoxic risks, but conflicting results have been obtained. The result of this review further stresses the need for scientific knowledge in this area and enhances the studies, above all, on people exposed for long periods.

Remifentanil and the brain.

BACKGROUND AND AIM: Remifentanil is an ultra-short-acting opioid, increasingly used today in neuroanesthesia and neurointensive care. Its characteristics make remifentanil a potentially ideal agent, but previous data have cast a shadow on this opioid, supporting potentially toxic effects on the ischemic brain. The aim of the present concise review is to survey available up-to-date information on the effects of remifentanil on the central nervous system. METHOD: A MEDLINE search within the past seven years for available up-to-date information on remifentanil and brain was performed. RESULTS: Concise up-to-date information on the effects of remifentanil on the central nervous system was reported, with a particular emphasis on the following topics: cerebral metabolism, electroencephalogram, electrocorticography, motor-evoked potentials, regional cerebral blood flow, cerebral blood flow velocity, arterial hypotension and hypertension, intracranial pressure, cerebral perfusion pressure, cerebral autoregulation, cerebrovascular CO(2) reactivity, cerebrospinal fluid, painful stimulation, analgesia and hyperalgesia, neuroprotection, neurotoxicity and hypothermia. CONCLUSION: The knowledge of the influence of remifentanil on brain functions is crucial before routine use in neuroanesthesia to improve anesthesia performance and patient safety as well as outcome.

Transcranial Doppler and anesthetics.

Transcranial Doppler (TCD) is widely used to investigate the effects of anesthetic drugs on cerebral blood flow. Its repeatability and non-invasivity makes it an ideal, first choice method. Anesthesia providers are required to be conscious of the cerebral hemodynamic effects of drugs given in their practice, especially in neurosurgery and in subjects with impaired brain functions. The purpose of this review is to present the basic concepts of the TCD technique and the effects on cerebral hemodynamics of the most popular anesthetic drugs evaluated using TCD ultrasonography.