Best practice & research. Clinical anaesthesiology
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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.
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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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Acute kidney injury (AKI) is a significant cause of perioperative patient morbidity and mortality. The definition of AKI has recently changed and further research is underway to identify clinically relevant biomarkers to aid in the diagnosis of the syndrome. ⋯ An anesthesiologist's main objective for perioperative renal protection is prevention by maintenance of euvolemia, preservation of adequate renal perfusion, and avoidance of nephrotoxins. This review will address the definition and diagnosis of AKI, identify patients at risk of AKI, and critically appraise management options for perioperative renal protection.
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Best Pract Res Clin Anaesthesiol · Mar 2008
ReviewBeta blockers and alpha2 agonists for cardioprotection.
Perioperative beta blockade or the use of alpha2 agonists remains a contentious and controversial area of perioperative medicine. Although there is no question that the liberal use of beta blockers (or alpha2 agonists) to prevent or reduce overt signs of sympathetic overactivity, particularly at known periods of stress (e.g. induction, incision, emergence, etc) is an important and routine part of the management of high risk patients, there remains considerable controversy in the literature regarding the efficacy of either short or long-term regimens on cardiac morbidity or long-term outcomes, particularly in those patients not previously receiving medication for known coronary artery disease or hypertension. The role of strict heart rate control (and its safety with regards to hypotension and possibly congestive heart failure) versus intermittent fixed dosing of beta blockers is particularly contentious. We consider the latest literature on this topic and identify areas of agreement and contention and present the latest recommendations of the American Heart Association/American College of Cardiology Perioperative Guidelines Group.
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Best Pract Res Clin Anaesthesiol · Mar 2008
ReviewPreconditioning, anesthetics, and perioperative medication.
Activation of endogenous signal transduction pathways, by a variety of stimuli including ischemic and anesthetic pre- and post-conditioning, protects myocardium against ischemia and reperfusion injury. Experimental evidence suggests that adenosine-regulated potassium channels, cyclooxygenase-2, intracellular kinases, endothelial nitric oxide synthase, and membrane bound receptors play critical roles in signal transduction, and that intracellular signaling pathways ultimately converge on mitochondria to produce cardioprotection. Disease states, and perioperative medications such as sulfonylureas and COX-2 antagonists, could have adverse effects on cardioprotection by impairing activation of ion channels and proteins that are important in cell signaling. Insights gained from animal and clinical studies are reviewed and recommendations given for the use of perioperative anesthetics and medications.