Seminars in respiratory and critical care medicine
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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.
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Hematologic factors, in particular platelets and the coagulation system, play an important role in the pathogenesis of organ failure in the intensive care unit. Failure of these hematologic systems is common in intensive care patients and may range from isolated thrombocytopenia or prolonged global clotting tests to complex defects, such as disseminated intravascular coagulation. There are many causes for a deranged coagulation in critically ill patients, and each of these underlying disorders may require specific therapeutic management. Hence, a proper differential diagnosis and initiation of adequate (supportive) treatment strategies are crucial to reduce morbidity and mortality in critically ill patients with coagulation abnormalities.
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Semin Respir Crit Care Med · Oct 2011
ReviewImmunologic alterations and the pathogenesis of organ failure in the ICU.
Rapid and marked alterations of innate and adaptive immunity typify the host response to systemic infection and acute inflammatory states. Immune dysfunction contributes to the development of organ failure in most patients with critical illness. The molecular mechanisms by which microbial pathogens and tissue injury activate myeloid cells and prime cellular and humoral immunity are increasingly understood. ⋯ In carefully selected patients, a better therapeutic strategy might be to provide immunoadjuvants to reconstitute immune function in intensive care unit (ICU) patients. Proresolving agents are also in development to terminate acute inflammatory reactions without immune suppression. This brief review summarizes the current understanding of the fundamental immune alterations in critical illness that lead to organ failure in critical illness.
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Cardiac alterations may be defined as changes that lead to abnormal cardiac function. They include decrease in preload, increase in afterload, and depressed cardiac contractility. Cardiac dysfunction differs from cardiac failure: cardiac performance is altered, but this does not necessarily mean that the cardiovascular system is failing. ⋯ Only when there is an imbalance between oxygen demand and oxygen transport is correction of cardiac alterations required. But the truth is that no study supports the use of one treatment rather than another. Changes in respiratory settings or in respiratory mechanics induce changes in cardiac function and must then be considered in the strategy.
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Central nervous system (CNS) failure represents a spectrum of disease ranging from mild neurological impairment that may have motor, sensory, visual, speech, cognitive manifestations, or a combination thereof, to comatose states and brain death. This article summarizes the common causes of CNS failure and analyzes the role of clinical, radiological, laboratory, and other ancillary testing in establishing the underlying diagnosis and assessing severity of CNS failure in each condition; we also comment on various treatment options for each of the causes of CNS failure.