Best practice & research. Clinical anaesthesiology
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Perioperative cardiac complications pose the greatest risk to the estimated 100 million people undergoing non-cardiac surgery each year. Most of these complications are related to underlying pre-existing coronary artery disease (CAD). For over 40 years researchers have been studying perioperative cardiac risk and how best to estimate it. ⋯ Risk stratification has taken on an important role in clinical decision-making, helping physicians decide in which patients additional medical therapies, such as coronary revascularization or perioperative beta-blockers, are necessary. Meta-analysis has found a significant improvement in the positive predictive value (PPV) for perioperative cardiac outcome with stress testing over that with clinical risk score alone. However, evidence is mounting that with the use of perioperative beta-blockers, the majority of intermediate and high-risk patients can safely undergo even major vascular surgery without further cardiac testing.
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Best Pract Res Clin Anaesthesiol · Mar 2008
ReviewHaemoglobin, oxygen carriers and perioperative organ perfusion.
Under normal conditions, only 20-30% of the delivered oxygen is metabolised. In normovolaemic anaemia, the organism reacts with increases in cardiac output and oxygen extraction. Once these mechanisms are exceeded, allogeneic blood transfusions may be administered. ⋯ The main groups of artificial oxygen carriers are extracellular haemoglobin solutions and perfluorocarbons. Preparations undergoing experimental and clinical assessment include Human Polymerized Haemoglobin (Polyheme), Polymerized Bovine Haemoglobin-based Oxygen Carrier (HBOC-201, Hemopure), Haemoglobin Raffimer (HemoLink), Diaspirin Cross-linked Haemoglobin (HemAssist), Human Recombinant Haemoglobin (rHb), Enzyme Cross-linked Poly-haemoglobin, Maleimide-activated Polyethylene-glycol Modified Haemoglobin (MP4, Hemospan), Zero-linked Haemoglobin (ZL-HbBv) and Recombinant Hybrid of Human-alpha-chains and Bovine-beta-chains and Perflubron (Oxygent). Research into some of these compounds has been discontinued, while others have advanced into clinical phase III trials, but none has achieved market approval for Europe, US or Canada so far.
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With recent advances in surgical and anaesthetic management, clinical medicine has responded to societal expectations and the number of operations in patients with a high-risk of perioperative liver failure has increased over the last decades. This review will outline important pathophysiological alterations common in patients with pre-existing liver impairment and thus highlight the anaesthetic challenge to minimise perioperative liver insults. It will focus on the intraoperative balancing act to reduce blood loss while maintaining adequate liver perfusion, the various anaesthetic agents used and their specific effects on hepatic function, perfusion and toxicity. Furthermore, it will discuss advances in pharmacological and ischaemic preconditioning and summarise the results of recent clinical trials.
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Best Pract Res Clin Anaesthesiol · Mar 2008
ReviewGlycaemic control and perioperative organ protection.
The concept of stress hyperglycaemia as an adaptive, beneficial response in critical illness has recently been challenged. Two large prospective randomized controlled trials in the Leuven University Hospital surgical and medical ICUs demonstrated that maintenance of normoglycaemia with intensive insulin therapy substantially prevents morbidity and reduces mortality. Strict normoglycaemia is required to gain most clinical benefit. ⋯ Other studies have been used to advocate against implementation of intensive insulin therapy by showing lack of benefit or questioning safety. However, these studies are inconclusive on this subject, due to problems of not reaching normal glucose levels clearly separated from the standard glycaemic group or lack of statistical power. Clearly, future studies should be adequately powered and comply with the study protocol in order to confirm the survival and other clinical benefits of intensive insulin therapy.