Arch Surg Chicago
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We provide an updated algorithm for approaching preoperative cardiac risk assessment in patients undergoing noncardiac surgery. ⋯ Most patients with high cardiac risk should proceed with coronary angiography. Patients with low cardiac risk can proceed to surgery without noninvasive testing. For intermediate-risk patients, consideration may be given to further stress testing prior to surgery; however, in most patients, proceeding to surgery with perioperative beta-blockade is an acceptable alternative.
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Oxidative stress has been implicated in the manifestations of critical illnesses, including ischemia and reperfusion injury and systemic inflammatory states. This review describes the evidence for increased oxidative stress in critically ill patients and explores the data regarding antioxidant therapy for these conditions. Antioxidant therapies reviewed include N-acetylcysteine, selenium, vitamins E and C, superoxide dismutase, catalase, lazaroids, and allopurinol. We focus on the results of these interventions in animal models and human trials, when available.
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Perioperative morbidity and mortality are frequently cardiac in origin. Many studies have prospectively attempted to define risk factors for cardiac ischemic events. ⋯ Treatment with beta-adrenergic antagonists decreases myocardial oxygen consumption and is generally well tolerated. This article reviews the physiologic and clinical basis for using these agents as prophylaxis against cardiovascular events in high-risk surgical patients.
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Review
Signaling mechanisms of altered cellular responses in trauma, burn, and sepsis: role of Ca2+.
Alterations in cellular responses in various organ systems contribute to trauma-, burn-, and sepsis-related multiple organ dysfunction syndrome. Such alterations in muscle contractile, hepatic metabolic, and neutrophil and T-cell inflammatory-immune responses have been shown to result from cell-signaling modulations and/or impairments in the respective cell types. Altered Ca(2+) signaling would seem to play an important role in the myocardial and vascular smooth muscle contractile dysfunction in the injury conditions; Ca(2+)-linked signaling derangement also plays a crucial role in sepsis-induced altered skeletal muscle protein catabolism and resistance to insulin-mediated glucose use. ⋯ The injury conditions would seem to cause an inappropriate up-regulation of Ca(2+)-signal generation in the skeletal myocyte, hepatocyte, and neutrophil, while they lead to a down-regulation of Ca(2+) signaling in T cells. The crucial signaling derangement that causes T-cell proliferation suppression seems to be a decrease in the activation of protein tyrosine kinases, which subsequently down-regulates Ca(2+) signaling. The delineation of cell-signaling derangements in trauma, burn, or sepsis conditions can lead to development of therapeutic interventions against the disturbed cellular responses in the vital organ systems.
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The approach to mechanical ventilation has been revolutionized by new insights into the pathogenesis of respiratory failure in acute respiratory distress syndrome (ARDS). Concepts such as low-volume ventilation, permissive hypercapnia, inverse ratio ventilation, best and intrinsic positive end-expiratory pressure, airway shear, pressure volume curves, inflection points, and prone positioning have radically transformed thinking about ventilator management. Since 1966, more than 8000 ARDS-related publications have appeared. ⋯ Selected clinical series that exemplify the use of these new strategies are reviewed, to demonstrate how key experimental and clinical research has altered our understanding about what works, and why. Mismanagement of mechanical ventilation causes lung injury and increases mortality. The strategy of protective ventilation has provided the first substantial reduction of mortality in the history of ARDS.