Seminars in respiratory and critical care medicine
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Lung failure is the most common organ failure seen in the intensive care unit. The pathogenesis of acute respiratory failure (ARF) can be classified as (1) neuromuscular in origin, (2) secondary to acute and chronic obstructive airway diseases, (3) alveolar processes such as cardiogenic and noncardiogenic pulmonary edema and pneumonia, and (4) vascular diseases such as acute or chronic pulmonary embolism. This article reviews the more common causes of ARF from each group, including the pathological mechanisms and the principles of critical care management, focusing on the supportive, specific, and adjunctive therapies for each condition.
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The physiological and biochemical abnormalities that constitute multiple organ failure represent cellular perturbations that, importantly, need to be reconciled with a lack of significant cell death together with availability but impaired utilization of oxygen. In conjunction with the relatively rapid ability of the organ to recover in surviving patients, a paradigm of metabolic shutdown triggered by a decrease in mitochondrial energy production appears increasingly valid. This review discusses data demonstrating temporal changes in oxygen utilization through the septic process, evidence for mitochondrial derangements, and recovery of mitochondrial function preceding clinical recovery.
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Acute renal failure (now acute kidney injury) is a common complication of critical illness affecting between 30 and 60% of critically ill patients. The development of a consensus definition (RIFLE--risk, injury, failure, loss, end-stage system) has allowed standardization of reporting and epidemiological work. Multicenter multinational epidemiological studies indicate that sepsis is now the most common cause of acute renal failure in the intensive care unit (ICU) followed by cardiac surgery-associated acute kidney injury. ⋯ Data from large observational studies and randomized, controlled trials consistently indicate that a positive fluid balance in patients with acute renal failure represents a major independent risk factor for mortality and provides no protection of renal function. The pendulum is clearly swinging away from a fluid-liberal approach to a fluid-conservative approach in these patients. Finally, there is a growing appreciation that acute renal failure may identify patients who are at increased risk of subsequent chronic renal dysfunction and mortality, opening the way to post-ICU interventional trials.
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Cardiovascular system failure is commonly faced by the intensivist. Heart failure can occur due to a host of predisposing cardiac disorders or as secondary effects of systemic illness. When the heart is unable to provide an adequate cardiac output to maintain adequate tissue perfusion, cardiogenic shock ensues. ⋯ Accurate and rapid identification of cardiogenic shock as a medical emergency, with expeditious implementation of appropriate therapy, can lead to improved clinical outcomes. In this review, we discuss optimal strategies for diagnosis and monitoring of cardiogenic shock. We discuss the diverse therapeutic strategies employed for cardiogenic shock, including pharmacological (e.g., vasoactive agents, fibrinolytic agents), mechanical (e.g., intraaortic balloon pumps, left ventricular assist devices, percutaneous coronary intervention [PCI]), and surgical approaches such as coronary artery bypass graft (CABG), valvular repair or replacement (e.g., for acute mitral regurgitation, ventricular septal rupture, or free wall rupture).
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Semin Respir Crit Care Med · Oct 2011
ReviewThe microcirculation as a therapeutic target in the treatment of sepsis and shock.
Largely ignored throughout the history of clinical medicine, the microcirculation has recently been recognized at the bedside as the center of several pathophysiological processes. Normal microcirculatory function is critical for adequate tissue oxygenation and organ function, but it has a poorly understood and highly heterogeneous structure that is related to the diversity of functions that it accomplishes. The most important function of the microcirculation is the regulation and distribution of oxygen carrying red blood cells within the different organs. ⋯ The introduction of bedside techniques into clinical practice that allow the evaluation of the microcirculation has opened up a new field of functional hemodynamic monitoring, identified the microcirculatory failure as the most sensitive indicator of circulatory failure associated with adverse outcome, and has provided the promise of identifying new therapeutic targets. Clinical research has identified various conventional and new therapeutic approaches that are successful in modifying the microcirculation. Current research must determine whether some of these approaches are successful in improving the outcome of critically ill patients by recruiting the microcirculation.