Best practice & research. Clinical anaesthesiology
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Best Pract Res Clin Anaesthesiol · Sep 2005
ReviewThe concept of anaesthetic-induced cardioprotection: mechanisms of action.
The mechanisms by which ischaemia reperfusion injury can be influenced have been the subject of extensive research in the last decades. Early restoration of arterial blood flow and surgical measures to improve the ischaemic tolerance of the tissue are the main therapeutic options currently in clinical use. In experimental settings ischaemic preconditioning has been described as protecting the heart, but the practical relevance of interventions by ischaemic preconditioning is strongly limited to these experimental situations. ⋯ Hence, the anaesthetist himself can substantially influence the critical situation of ischaemia reperfusion during the operation by choosing the right anaesthetic. A better understanding of the underlying mechanisms of anaesthetic-induced cardioprotection not only reflects an important increase in scientific knowledge but may also offer the new perspective of using different anaesthetics for targeted intraoperative myocardial protection. There are three time windows when a substance may interact with the ischaemia reperfusion injury process: (1) during ischaemia, (2) after ischaemia (i.e. during reperfusion), and (3) before ischaemia (preconditioning).
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Best Pract Res Clin Anaesthesiol · Sep 2005
ReviewMechanisms of general anesthesia: from molecules to mind.
Despite the widespread presence of clinical anesthesiology in medical practice, the mechanism by which diverse inhalational agents result in the state of general anesthesia remains unknown. Over recent decades, our understanding of general anesthetic mechanisms has evolved dramatically from early unitary hypotheses, largely due to the development and influence of a myriad of scientific disciplines ranging from molecular biology to cognitive neuroscience. ⋯ In this chapter, we review the major hypotheses of general anesthetic mechanisms of action and present an expanded overview of current investigation into those mechanisms. We also present a framework to aid in thinking about the actions of these agents, highlighting the relationship between putative targets at the molecular level and the more integrated functional changes in behavior and consciousness.
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Best Pract Res Clin Anaesthesiol · Sep 2005
ReviewLow flow and economics of inhalational anaesthesia.
Even when anaesthesia does not represent a major part of the expense of a given surgical operation, reducing costs is not negligible because the large number of patients passing through a department of anaesthesia accounts for a huge annual budget. Volatile anaesthetics contribute 20% of the drug expenses in anaesthesia, coming just behind the myorelaxants; however, the cost of halogenated agents has potential for savings because a significant part of the delivered amount is wasted when a non- or partial-rebreathing system is used. The cost of inhaled agents is related to more than the amount taken up; it also depends on their market prices, their relative potencies, the amount of vapour released per millilitre of liquid, and last but not least the fresh-gas flow rate (FGF) delivered to the vaporizer--the most important factor determining the cost of anaesthesia. ⋯ Isoflurane, the cheapest generic agent, might be advantageous for maintenance of anaesthesia of less than 3 hours. Sevoflurane is the agent of choice for inhalational induction and might also be used for maintenance. Desflurane might be preferred for long anaesthetics where rapid recovery will generate savings in the PACU.
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Best Pract Res Clin Anaesthesiol · Jun 2005
Review Meta AnalysisLocal anaesthesia for pain relief after laparoscopic cholecystectomy--a systematic review.
Local anaesthetics (LA) are increasingly being used intraoperatively for the prevention of postoperative pain. The efficacy of local anaesthetic infiltration into incision sites has only been shown in patients undergoing inguinal herniorrhaphy. However, in one meta-analysis of the literature, intraperitoneal LA have been shown to be effective for pain relief following laparoscopic cholecystectomy (LC). ⋯ Although side effects are rare, the dose of LA should be monitored closely to avoid toxicity. Future studies should be directed towards determining whether the analgesic effects of LA are via peripheral mechanisms or systemic absorption. The explanation for the wide interindividual variation in pain following LC should also be better investigated.
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Best Pract Res Clin Anaesthesiol · Jun 2005
ReviewBupivacaine, levobupivacaine and ropivacaine: are they clinically different?
Two new, long-acting local anaesthetics have been developed after the evidence of bupivacaine-related severe toxicity: levobupivacaine and ropivacaine. Both these agents are pure left-isomers and, based on their three-dimensional structure, they have less toxic potential both on the central nervous system and on the heart. ⋯ Evaluating randomised, controlled trials that have compared these three local anaesthetics, this chapter supports the evidence that both levobupivacaine and ropivacaine have a clinical profile similar to that of racemic bupivacaine, and that the minimal differences observed between the three agents are mainly related to the slightly different anaesthetic potency, with racemic bupivacaine>levobupivacaine>ropivacaine. However, the reduced toxic potential of the two pure left-isomers supports their use in those clinical situations in which the risk of systemic toxicity related to either overdosing or unwanted intravascular injection is high, such as during epidural or peripheral nerve blocks.