Current opinion in critical care
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Diaphragmatic function is a major determinant of the ability to successfully wean patients from mechanical ventilation. There is increasing recognition of a condition termed ventilator-induced diaphragmatic dysfunction. The purpose of the present review is to present evidence that mechanical ventilation can itself be a cause of diaphragmatic dysfunction, to outline our current understanding of the cellular mechanisms responsible for this phenomenon, and to discuss the implications of recent research for future therapeutic strategies. ⋯ Diaphragmatic dysfunction is common in mechanically ventilated patients and is a likely cause of weaning failure. Recently, there has been a great expansion in our knowledge of how mechanical ventilation can adversely affect diaphragmatic structure and function. Future studies need to better define the evolution and mechanistic basis for ventilator-induced diaphragmatic dysfunction in humans, in order to allow the development of mechanical ventilation strategies and pharmacologic agents that will decrease the incidence of ventilator-induced diaphragmatic dysfunction.
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Acute kidney injury contributes to the development of acute lung injury and vice-versa. Volume overload that may occur during renal impairment increases pulmonary capillary hydrostatic pressure. However, experimental evidence clearly shows that lung damage occurs even in the absence of positive fluid balance. However, acute lung injury with its attendant hypoxemia, hypercapnia and mechanical ventilation worsens renal hemodynamics and function. ⋯ Fluid management optimization and prevention of inflammation and lung stretching are currently recommended for the treatment of acute lung and renal injury. Extracorporeal CO2 removal and renal replacement associated with extracorporeal membrane oxygenation might be interesting options for a future approach to pulmonary/renal syndrome.
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Curr Opin Crit Care · Feb 2010
ReviewClinical trials in ventilator treatment: current perspectives and future challenges.
Mortality/morbidity-based end points have been useful in evaluating treatments that modulate 'mediator variables' with a large effect size. Ventilation is usually a supportive measure, and hence is best seen as a 'moderator variable'. It can, therefore, have only a modest impact on disease-specific mortality. In this context, over reliance on final outcome-based end points (mortality, length of stay, etc.) risks the abandonment of several potentially useful developments. These concepts are important in considering how future developments should be evaluated. ⋯ It is crucial that a more dynamic approach, not based on final outcome alone, is considered in designing new clinical trials involving new ventilation strategies.
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Innovative modes of mechanical ventilation, mainly based on complex closed loop technologies, have been recently developed and are now available for clinical use. ⋯ The recently reported results with proportional assist ventilation with load-adjustable gain factors, neurally adjusted ventilatory assist, and adaptive support ventilation are, till now, mainly based on preliminary physiologic and clinical studies; although they seem to be promising, suggesting that closed loop-based modes could represent a real innovation in the field of mechanical ventilation, further clinical evaluation is needed before their widespread diffusion into clinical practice.
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Curr Opin Crit Care · Feb 2010
ReviewPharmacological treatments for acute respiratory distress syndrome.
Studies of the pharmacologic management of acute respiratory distress syndrome (ARDS) have yielded conflicting results. The purpose of this review is to discuss recent pharmacologic trials in ARDS, using the conceptual framework of ARDS as a heterogeneous disease. ⋯ ARDS is a heterogeneous syndrome. Failure to target subgroups more likely to benefit from specific therapies may be one explanation for largely disappointing trial results so far.