Current opinion in critical care
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Acute lung injury and its extreme manifestation, acute respiratory distress syndrome, complicate a wide variety of serious medical and surgical conditions, only some of which affect the lung directly. Despite recent evidence-based advances in clinical management, acute lung injury and acute respiratory distress syndrome are associated with significant mortality. Detailed epidemiology is essential in guiding the recruitment of patients into trials of new therapeutic interventions, thereby improving outcome and allowing directed allocation of scarce resources. ⋯ Recent epidemiologic studies of the incidence of acute lung injury and acute respiratory distress syndrome have indicated a similar incidence in developed societies, and they confirm that mortality is falling in comparison with a decade ago. The awaited publication of new consensus guidelines for the definition of acute lung injury and acute respiratory distress syndrome may render new studies necessary.
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The purpose of this review is to provide a historical perspective and to analyze the recent advances in the understanding of the cellular and tissue pathology of acute respiratory failure, specifically of the acute respiratory distress syndrome. The scope of mechanisms involved in acute lung injury and acute respiratory distress syndrome is far too great to do it justice in a single review. Therefore, this review will focus only on recent advances in the understanding of the morphologic changes that occur in acute lung injury, acute respiratory distress syndrome, and ventilator-induced lung injury. ⋯ New mechanisms in the pathology of acute respiratory failure have shifted the focus to lung mechanics, tissue damage, remodeling, and the systemic effects derived from the mechanical stress imposed by the ventilator in patients with adult respiratory distress syndrome.
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Extracorporeal membrane oxygenation (ECMO) has become a more or less accepted standard in the algorithm of advanced acute respiratory distress syndrome therapy in adult patients when all other treatment options have failed. This article reviews the current status of ECMO therapy with particular focus on new technical developments and their potential implications for performance and indications for ECMO therapy. ⋯ Over the years, the technique for ECMO therapy underwent substantial changes in indications and the materials used. Impressive technical progress has been made in pumps, oxygenators, and coating of artificial surfaces, leading to a higher biocompatibility and to a lower rate of procedure-related complications. The potential of new inline pumps in combination with a decreasing rate of procedure-related complications might lead to a re-evaluation of the role of extracorporeal lung support in acute respiratory distress syndrome therapy. A very recent development is the use of spontaneous arteriovenous devices for carbon dioxide removal, allowing significant reduction of ventilator settings at decreased carbon dioxide partial pressures and at increased pH values. Ongoing studies are looking at the potential of this approach to reduce side effects of mechanical ventilation further.
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Curr Opin Crit Care · Feb 2005
ReviewPermissive hypercapnia: role in protective lung ventilatory strategies.
Hypercapnia is a central component of current protective ventilatory strategies. This review aims to present and interpret data from recent clinical and experimental studies relating to hypercapnia and its role in protective ventilatory strategies. ⋯ The potential for hypercapnia to contribute to the beneficial effects of protective lung ventilatory strategies is clear from experimental studies. However, the optimal ventilatory strategy and the precise contribution of hypercapnia to this strategy remain unclear. A clearer understanding of its effects and mechanisms of action is central to determining the safety and therapeutic utility of hypercapnia in protective lung ventilatory strategies.
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Mechanical ventilation is usually provided in acute lung injury to ensure alveolar ventilation and reduce the patients' work of breathing without further damaging the lungs by the treatment itself. Although partial ventilatory support modalities were initially developed for weaning from mechanical ventilation, they are increasingly used as primary modes of ventilation, even in patients in the acute phase of pulmonary dysfunction. The aim of this paper is to review the role of spontaneous breathing ventilatory modalities with respect to their physiologic or clinical evidence. ⋯ On the basis of currently available data, the authors suggest the use of techniques of mechanical ventilatory support that maintain, rather than suppress, spontaneous ventilatory effort, especially in patients with severe pulmonary dysfunction.