Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Aug 2006
ReviewEpidemiology of acute lung injury and acute respiratory distress syndrome.
Acute respiratory distress syndrome (ARDS) is a heterogeneous disorder that may be triggered by myriad etiologies (both pulmonary and extrapulmonary). Mortality rates for ARDS range from 30 to 75%, and most deaths are a consequence of multiorgan failure (MOF). ⋯ This review discusses limitations of various criteria utilized to diagnosis ARDS and ALI, and why some criteria may be problematic when designing clinical trials. Also discussed are the myriad causes of ARDS, incidence, epidemiology, mortality, and factors that influence outcome.
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The importance of pulmonary surfactant in maintaining normal lung function, and the observations that alterations in endogenous surfactant contribute to the lung dysfunction associated with acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS), provide a rationale for administering exogenous surfactant in this setting. The results of clinical trials have been variable, however, in part due to the various surfactant preparations used, the different delivery and dosing methods employed, and the types of patients targeted for this therapy. ⋯ Based on extensive in vitro data as well as in vivo animal studies demonstrating the anti-inflammatory and antibacterial functions of various surfactant components, administration of surfactant earlier in the course of the disease, when lung inflammation is present but before severe lung dysfunction occurs, may prove to be optimal. This review discusses both the biophysical and host defense functions of surfactant in the context of novel therapeutic approaches for patients with ALI/ARDS.
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Semin Respir Crit Care Med · Aug 2006
ReviewPathophysiology of acute lung injury and the acute respiratory distress syndrome.
Since the adult respiratory distress syndrome was first described substantial progress has been made in understanding the pathogenesis of this complex syndrome. This review summarizes our current understanding of the pathophysiology of what is now termed the acute respiratory distress syndrome (ARDS) and its less severe form acute lung injury (ALI), with an emphasis on cellular and molecular mechanisms of injury that may represent potential therapeutic targets. Although it is difficult to synthesize all of these abnormalities into a single, unified, pathogenetic pathway, a theme that emerges repeatedly is that of imbalance, be it between pro- and anti-inflammatory cytokines, oxidants and antioxidants, procoagulants and anticoagulants, neutrophil recruitment and activation and mechanisms of neutrophil clearance, or proteases and protease inhibitors. Future therapies aimed at restoring the overall balance of cytokines, oxidants, coagulants, and proteases may ultimately be successful where therapies that target individual cytokines or other mediators have not.
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Semin Respir Crit Care Med · Jun 2006
ReviewInfection control and the prevention of nosocomial infections in the intensive care unit.
Nosocomial infections continue to be significant causes of morbidity, mortality, and added costs in the health care setting. Half of all life-threatening nosocomial bloodstream infections and pneumonias occur in intensive care units (ICUs), despite ICUs representing only 15 to 20% of all hospital beds. Thus an efficient focus for prevention and control of life-threatening health care-associated infections should be in ICUs. ⋯ Strict adherence to evidence-based catheter insertion and maintenance policies reduces nosocomial bloodstream infections. Evidence-based prevention strategies for ventilator-associated pneumonia, including management of respiratory equipment according to published guidelines and maintaining backrest elevation at 30 to 45 degrees, are effective. For greatest risk reduction, multifaceted programs ensuring maximal adherence with evidence-based infection control guidelines are needed.
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Semin Respir Crit Care Med · Jun 2006
ReviewStress hyperglycemia and adrenal insufficiency in the critically ill.
Critical illness evoked by trauma, extensive surgery, or severe medical illnesses is the ultimate example of acute severe physical stress. The endocrine response in a critically injured and stressed patient is varied and complex. ⋯ In addition, patients may have preexisting endocrine diseases, either previously diagnosed or unknown, and hence endocrine evaluation in a critically ill patient poses a major challenge to the health care provider. This review provides a novel insight into the dynamic endocrine alterations that occur during evolution of stress hyperglycemia and adrenal insufficiency in the critically ill patient and the available evidence for the therapy of these disorders.