Current opinion in critical care
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Mechanical ventilation is a supportive lifesaving therapy that can potentially cause lung injury if periodic alveolar overdistension, or cyclic collapse, and reopening occur. The use of a low tidal volume with moderate to high positive end-expiratory pressure improves the survival of patients with acute lung injury and acute respiratory distress syndrome. Positioning the patient with the "good lung down" and using differential ventilation with selective positive end-expiratory pressure are the two currently accepted ventilatory strategies to be applied in patients with severe unilateral lung injury. ⋯ In unilateral lung injury, ventilatory strategies that allow recruitment of injured lung and that avoid overdistension of uninjured lung parenchyma should be applied. Experimental studies have shown that the use of selective tracheal gas insufflation and partial liquid ventilation facilitates low tidal volume with appropriate gas exchange while reducing cyclic lung stretch and shear stresses. Further studies are needed to determine future applications of these therapies in humans.
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Curr Opin Crit Care · Feb 2003
ReviewWhy protect the right ventricle in patients with acute respiratory distress syndrome?
Even a slight increase in pulmonary vascular resistance can overload a normal right ventricle, which ejects blood through a low-pressure circuit. In a clinical setting, a persistent increase in pulmonary vascular resistance produces acute cor pulmonale. From an echocardiographic point of view, may be defined as the combination of a paradoxical septal motion, reflecting systolic overload, with right ventricular enlargement, reflecting diastolic overload. ⋯ This prognosis has greatly improved with protective ventilation. At the same time, the incidence of acute cor pulmonale has diminished in acute respiratory distress syndrome, and the prognosis of this specific complication has also improved, suggesting that the right ventricle may develop some adaptation against persistent overload. Past lessons, however, have taught us that this potential may be limited and lead us to recommend right ventricular protection during mechanical ventilation.
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In this review, we discuss the heat shock response, a specific example of gene expression that has been studied over the past 25 years, and its relevance to acute lung injury and other critical conditions. The heat shock response has been observed in virtually all organisms and involves the rapid induction of a set of highly conserved genes that encode heat shock proteins (HSPs). ⋯ The capacity of HSPs to subserve cytoprotection has produced considerable interest from the perspective of elucidating the pathophysiology of organ damage and dysfunction. Several studies support the hypothesis that HSPs are cytoprotective In addition, recent investigations have demonstrated that HSP70 is released into the systemic circulation and is involved in the activation of innate immunity.
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Critical care medicine is a relatively young specialty that was developed in response to potentially reversible life-threatening illness and was facilitated by developments such as new drugs, support equipment, and monitoring technology. It has been largely practiced within the four walls of an intensive care unit (ICU). However, now there are increasing numbers of critically ill and at-risk patients in acute hospitals who are suffering potentially preventable, serious complications that may result in death because of a lack of appropriate systems, skills, and expertise outside of the ICU. Critical care specialists are expanding their roles beyond the four walls of their ICUs and becoming involved with strategies such as the medical emergency team, a concept designed to recognize critical illness early and to respond rapidly to resuscitate patients wherever they are in the hospital.